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Albert Einstein Quotes About Time Travel

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Albert Einstein quote: Life is like riding a bicycle. To keep your balance, you must keep...

Life is like riding a bicycle. To keep your balance, you must keep moving.

The distinction between the past, present and future is only a stubbornly persistent illusion.

I love to travel, but hate to arrive.

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Albert Einstein

Born: March 14, 1879
Died: April 18, 1955
Occupation: Theoretical Physicist
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Albert Einstein Quotes About Time

MS Lina Pierce

Albert Einstein, the genius physicist and the father of the theory of relativity, had a unique perspective on time. His profound insights have left us with a treasure trove of quotes that challenge our understanding of time, time travel, and the relativity of time. These quotes not only reflect his scientific brilliance but also his philosophical depth. In this blog post, we delve into 45 of Einstein’s most thought-provoking quotes about time, each accompanied by a brief explanation to help you grasp the essence of his wisdom.

“The only reason for time is so that everything doesn’t happen at once.” — This quote suggests that time serves as a medium to sequence events.
“Time and space are modes by which we think and not conditions in which we live.” — Einstein implies that time and space are constructs of our mind.
“Time is relative; its only worth depends upon what we do as it is passing.” — Here, Einstein emphasizes the subjective nature of time[11].
“I never think of the future — it comes soon enough.” — This quote reflects Einstein’s focus on the present moment.
“When forced to summarize the general theory of relativity in one sentence: Time and space and gravitation have no separate existence from matter.” — Einstein encapsulates his groundbreaking theory in this quote.

Albert Einstein Quotes About Time Travel

“For us believing physicists, the distinction between past, present, and future is only an illusion, even if a stubborn one.” — Einstein suggests that time is not linear, a concept crucial to the idea of time travel.
“The separation between past, present, and future is only an illusion, although a convincing one.” — This quote further emphasizes the non—linear nature of time.
“People like us, who believe in physics, know that the distinction between past, present, and future is only a stubbornly persistent illusion.” — Einstein reiterates that time is an illusion, a concept that challenges our conventional understanding of time and opens up the possibility of time travel.
“The only reason for time is so that everything doesn’t happen at once.” — This quote, while not directly about time travel, suggests the possibility of events occurring outside their usual sequence, a key concept in time travel.
“Space and time are not conditions in which we live, but modes in which we think.” — Einstein suggests that our perception of time can be altered, a concept that is central to the idea of time travel.

Albert Einstein Quotes About the Relativity of Time

“When you sit with a nice girl for two hours, it seems like two minutes. When you sit on a hot stove for two minutes, it seems like two hours. That’s relativity.” — Einstein uses a humorous analogy to explain the concept of relativity.
“Put your hand on a hot stove for a minute, and it seems like an hour. Sit with a pretty girl for an hour, and it seems like a minute. That’s relativity.” — This is another version of the previous quote, further illustrating the concept of relativity.
“The only reason for time is so that everything doesn’t happen at once.” — This quote, while not directly about the relativity of time, suggests that time can be experienced differently depending on the observer, a key concept in relativity.
“Time is what prevents everything from happening at once.” — Einstein humorously points out the organizing function of time, a concept that is central to the theory of relativity.
“The distinction between the past, present, and future is only a stubbornly persistent illusion.” — Einstein challenges our linear perception of time, a concept that is central to the theory of relativity.

Check: Albert Einstein Quotes on Relativity with Explanations

Albert Einstein’s quotes about time provide a fascinating insight into his revolutionary understanding of the universe. His views challenge our conventional understanding of time as a linear, unchanging entity, and open up a world of possibilities including time travel and the relativity of time. These quotes not only reflect Einstein’s scientific genius but also his ability to convey complex ideas in a relatable and often humorous way.

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Einstein's equation and time travel

How is Einstein's equation (Gμν = 8πG Tμν) actually applied? And how does it support the theory of time travel.

Many physicists refer to this as Einstein’s Equations (plural) because it's actually a set of several equations. The symbol Gμν denotes the "Einstein tensor," which is a measure of how much space-time is curving. The symbol Tμν denotes the "energy momentum tensor," which measures the density and flux of the energy and momentum of matter. The energy and momentum of matter causes space-time to curve in a way that is described by Einstein’s Equations. The curvature of space-time is what causes all the effects that we associate with "gravity."

There are many textbooks that explain how to apply Einstein’s Equations equations to various situations, but they require a very advanced background in physics and mathematics. I will therefore have to summarize things in words.

Before talking about time travel, let me first explain what a "world-line" is. Suppose that an object at a particular time is sitting at some particular point in space. At another time, it will be sitting at another point. Its locations at different times trace out a path through space-time, which is called the object’s world line. This path extends forward to points farther and farther in the future (until the object ceases to exist for some reason, at which point its world-line ends). But imagine that an object’s world-line bends around in a loop, so that at it arrives at a point in space-time where it had already been? For example, there may be a point on my world line that was me at my fifth birthday party at my parents’ home in New York City. Another point (farther along my world-line) is me now, aged 61, sitting in my office at the University of Delaware. If I continue farther and farther along my world line, might I end up again at my fifth birthday party in New York City in 1958? Could my five-year old self meet my much older self at that party? That is what most people mean by "time travel." In the jargon of physics, such a world line that bent around and intersected itself is called a "closed time-like loop" or "closed time-like curve."

The question is whether world-lines that are closed time-like loops are possible in the real world. It is comparatively easy to show that if space-time were not curved world-lines would definitely not be able to bend around to form closed time-like loops. But one might hope that gravity, by curving space-time, could bend some world-lines around to make closed loops. The way people have studied this question is to assume that Einstein’s equations correctly describe how the energy and momentum of matter curves space-time. Then they look for solutions of those equations where space-time curves in such a way as to make closed time-like loops possible, and therefore time-travel possible. No one has ever found such solutions. People have on occasion found what seemed to be such solutions, but on closer inspection it was found that when realistic conditions are imposed, no time travel is possible. An example is the Gödel Universe (or Gödel metric).

One kind of solution that would allow time travel is called a "Minkowski wormhole." A Minkowski wormhole would be like a tunnel that took you from one point in space-time to what seemed like a far distant point--a point far away in space, or in the past, or in the future. But people have shown that for a Minkowski wormhole to exist, there would have to be a type of matter whose energy and momentum were unlike any kind of matter ever seen and extremely unlikely to exist in the real world.

The great majority of experts believe that time travel is not allowed by the laws of physics. But no one has proved that rigorously. If you want to learn more, you could try to find discussions of closed time-like loops and Minkowski wormholes in books or on the internet.

-Stephen Barr

General relativity

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25 Quotes That Take You Inside Albert Einstein’s Revolutionary Mind

Over the years, Albert Einstein’s name has become synonymous with genius.

In his lifetime, Einstein changed the world, describing the workings of reality better than anyone since Isaac Newton and revealing the capabilities of the atom bomb. In 1999, Time named him Person of the Century .

Here are 25 of Einstein’s most telling quotes; each will take you inside the mind of the legend.

On authority

“Unthinking respect for authority is the greatest enemy of truth.”

[“The Curious History of Relativity”]

“Nature shows us only the tail of the lion. But there is no doubt in my mind that the lion belongs with it even if he cannot reveal himself to the eye all at once because of his huge dimension.”

[Smithsonian, February 1979]

On politics

“I am by heritage a Jew, by citizenship a Swiss, and by makeup a human being, and only a human being, without any special attachment to any state or national entity whatsoever.”

[“The Yale Book of Quotations”]

On certainty

“As far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality.”

[Address to Prussian Academy of Science, January 1921]

On humility

“As a human being, one has been endowed with just enough intelligence to be able to see clearly how utterly inadequate that intelligence is when confronted with what exists.”

[Letter to Queen Elisabeth of Belgium, September 1932]

On relativity

“When a man sits with a pretty girl for an hour, it seems like a minute. But let him sit on a hot stove for a minute — and it’s longer than any hour. That’s relativity.”

On his growth

“It is true that my parents were worried because I began to speak fairly late, so that they even consulted a doctor. I can’t say how old I was — but surely not less than three.”

[Letter, 1954]

On common sense

“Common sense is nothing more than a deposit of prejudices laid down in the mind before you reach eighteen.”

[“The Universe and Dr. Einstein”]

“If A is a success in life, then A equals X plus Y plus Z. Work is X; Y is play, and Z is keeping your mouth shut.”

On nationalism

“Nationalism is an infantile sickness. It is the measles of the human race.”

[“Albert Einstein, the Human Side”]

“The most beautiful experience we can have is the mysterious. It is the fundamental emotion that stands at the cradle of true art and true science. Whoever does not know it and can no longer wonder, no longer marvel, is as good as dead, and his eyes are dimmed.”

[“The World As I See It,” 1930]

On solitude

“My passionate sense of social justice and social responsibility has always contrasted oddly with my pronounced lack of need for direct contact with other human beings and human communities. I am truly a ‘lone traveler’ and have never belonged to my country, my home, my friends, or even my immediate family, with my whole heart; in the face of all these ties, I have never lost a sense of distance and a need for solitude.”

On presentation

“If I were to start taking care of my grooming, I would no longer be my own self.”

[Letter, December 1913]

On imagination

“Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.”

On motivation

“The ideals that have lighted my way, and time after time have given me new courage to face life cheerfully, have been Kindness, Beauty, and Truth. Without the sense of kinship with men of like mind, without the occupation with the objective world, the eternally unattainable in the field of art and scientific endeavors, life would have seemed empty to me. The trite objects of human efforts — possessions, outward success, luxury — have always seemed to me contemptible.”

On education

“The aim [of education] must be the training of independently acting and thinking individuals who, however, see in the service to the community their highest life problem.”

[Address, October 1936]

On ambition

“Nothing truly valuable arises from ambition or from a mere sense of duty; it stems rather from love and devotion towards men and towards objective things.”

[Letter, July 1947]

On learning

“Most teachers waste their time by asking questions that are intended to discover what a pupil does not know, whereas the true art of questioning is to discover what the pupil does know or is capable of knowing.”

[“Conversations with Albert Einstein,” 1920]

On thinking

“I very rarely think in words at all. A thought comes, and I may try to express in words afterwards.”

[“Productive Thinking,” 1959]

“A happy man is too satisfied with the present to dwell too much on the future.”

On curiosity

“The important thing is to not stop questioning. Curiosity has its own reason for existing.”

On work ethic

“The state of mind which enables a man to do work of this kind … is akin to that of the religious worshipper or the lover; the daily effort comes from no deliberate intention or program, but straight from the heart.”

[Speech, 1918]

On childhood

“The ordinary adult never gives a thought to space-time problems … I, on the contrary, developed so slowly that I did not begin to wonder about space and time until I was an adult. I then delved more deeply into the problem than any other adult or child would have done.”

[Letter, 1956]

On the role of science

“One thing I have learned in a long life: That all our science, measured against reality, is primitive and childlike — and yet it is the most precious thing we have.”

[“Albert Einstein: Creator and Rebel,” 1972]

On the hustle

“The only way to escape the corruptible effect of praise is to go on working.”

This article originally appeared on Business Insider .

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Is Time Travel Possible?

We all travel in time! We travel one year in time between birthdays, for example. And we are all traveling in time at approximately the same speed: 1 second per second.

We typically experience time at one second per second. Credit: NASA/JPL-Caltech

NASA's space telescopes also give us a way to look back in time. Telescopes help us see stars and galaxies that are very far away . It takes a long time for the light from faraway galaxies to reach us. So, when we look into the sky with a telescope, we are seeing what those stars and galaxies looked like a very long time ago.

However, when we think of the phrase "time travel," we are usually thinking of traveling faster than 1 second per second. That kind of time travel sounds like something you'd only see in movies or science fiction books. Could it be real? Science says yes!

Image of galaxies, taken by the Hubble Space Telescope.

This image from the Hubble Space Telescope shows galaxies that are very far away as they existed a very long time ago. Credit: NASA, ESA and R. Thompson (Univ. Arizona)

How do we know that time travel is possible?

More than 100 years ago, a famous scientist named Albert Einstein came up with an idea about how time works. He called it relativity. This theory says that time and space are linked together. Einstein also said our universe has a speed limit: nothing can travel faster than the speed of light (186,000 miles per second).

Einstein's theory of relativity says that space and time are linked together. Credit: NASA/JPL-Caltech

What does this mean for time travel? Well, according to this theory, the faster you travel, the slower you experience time. Scientists have done some experiments to show that this is true.

For example, there was an experiment that used two clocks set to the exact same time. One clock stayed on Earth, while the other flew in an airplane (going in the same direction Earth rotates).

After the airplane flew around the world, scientists compared the two clocks. The clock on the fast-moving airplane was slightly behind the clock on the ground. So, the clock on the airplane was traveling slightly slower in time than 1 second per second.

Credit: NASA/JPL-Caltech

Can we use time travel in everyday life?

We can't use a time machine to travel hundreds of years into the past or future. That kind of time travel only happens in books and movies. But the math of time travel does affect the things we use every day.

For example, we use GPS satellites to help us figure out how to get to new places. (Check out our video about how GPS satellites work .) NASA scientists also use a high-accuracy version of GPS to keep track of where satellites are in space. But did you know that GPS relies on time-travel calculations to help you get around town?

GPS satellites orbit around Earth very quickly at about 8,700 miles (14,000 kilometers) per hour. This slows down GPS satellite clocks by a small fraction of a second (similar to the airplane example above).

Illustration of GPS satellites orbiting around Earth

GPS satellites orbit around Earth at about 8,700 miles (14,000 kilometers) per hour. Credit: GPS.gov

However, the satellites are also orbiting Earth about 12,550 miles (20,200 km) above the surface. This actually speeds up GPS satellite clocks by a slighter larger fraction of a second.

Here's how: Einstein's theory also says that gravity curves space and time, causing the passage of time to slow down. High up where the satellites orbit, Earth's gravity is much weaker. This causes the clocks on GPS satellites to run faster than clocks on the ground.

The combined result is that the clocks on GPS satellites experience time at a rate slightly faster than 1 second per second. Luckily, scientists can use math to correct these differences in time.

Illustration of a hand holding a phone with a maps application active.

If scientists didn't correct the GPS clocks, there would be big problems. GPS satellites wouldn't be able to correctly calculate their position or yours. The errors would add up to a few miles each day, which is a big deal. GPS maps might think your home is nowhere near where it actually is!

In Summary:

Yes, time travel is indeed a real thing. But it's not quite what you've probably seen in the movies. Under certain conditions, it is possible to experience time passing at a different rate than 1 second per second. And there are important reasons why we need to understand this real-world form of time travel.

If you liked this, you may like:

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Time Travel

There is an extensive literature on time travel in both philosophy and physics. Part of the great interest of the topic stems from the fact that reasons have been given both for thinking that time travel is physically possible—and for thinking that it is logically impossible! This entry deals primarily with philosophical issues; issues related to the physics of time travel are covered in the separate entries on time travel and modern physics and time machines . We begin with the definitional question: what is time travel? We then turn to the major objection to the possibility of backwards time travel: the Grandfather paradox. Next, issues concerning causation are discussed—and then, issues in the metaphysics of time and change. We end with a discussion of the question why, if backwards time travel will ever occur, we have not been visited by time travellers from the future.

1.1 Time Discrepancy

1.2 changing the past, 2.1 can and cannot, 2.2 improbable coincidences, 2.3 inexplicable occurrences, 3.1 backwards causation, 3.2 causal loops, 4.1 time travel and time, 4.2 time travel and change, 5. where are the time travellers, other internet resources, related entries, 1. what is time travel.

There is a number of rather different scenarios which would seem, intuitively, to count as ‘time travel’—and a number of scenarios which, while sharing certain features with some of the time travel cases, seem nevertheless not to count as genuine time travel: [ 1 ]

Time travel Doctor . Doctor Who steps into a machine in 2024. Observers outside the machine see it disappear. Inside the machine, time seems to Doctor Who to pass for ten minutes. Observers in 1984 (or 3072) see the machine appear out of nowhere. Doctor Who steps out. [ 2 ] Leap . The time traveller takes hold of a special device (or steps into a machine) and suddenly disappears; she appears at an earlier (or later) time. Unlike in Doctor , the time traveller experiences no lapse of time between her departure and arrival: from her point of view, she instantaneously appears at the destination time. [ 3 ] Putnam . Oscar Smith steps into a machine in 2024. From his point of view, things proceed much as in Doctor : time seems to Oscar Smith to pass for a while; then he steps out in 1984. For observers outside the machine, things proceed differently. Observers of Oscar’s arrival in the past see a time machine suddenly appear out of nowhere and immediately divide into two copies of itself: Oscar Smith steps out of one; and (through the window) they see inside the other something that looks just like what they would see if a film of Oscar Smith were played backwards (his hair gets shorter; food comes out of his mouth and goes back into his lunch box in a pristine, uneaten state; etc.). Observers of Oscar’s departure from the future do not simply see his time machine disappear after he gets into it: they see it collide with the apparently backwards-running machine just described, in such a way that both are simultaneously annihilated. [ 4 ] Gödel . The time traveller steps into an ordinary rocket ship (not a special time machine) and flies off on a certain course. At no point does she disappear (as in Leap ) or ‘turn back in time’ (as in Putnam )—yet thanks to the overall structure of spacetime (as conceived in the General Theory of Relativity), the traveller arrives at a point in the past (or future) of her departure. (Compare the way in which someone can travel continuously westwards, and arrive to the east of her departure point, thanks to the overall curved structure of the surface of the earth.) [ 5 ] Einstein . The time traveller steps into an ordinary rocket ship and flies off at high speed on a round trip. When he returns to Earth, thanks to certain effects predicted by the Special Theory of Relativity, only a very small amount of time has elapsed for him—he has aged only a few months—while a great deal of time has passed on Earth: it is now hundreds of years in the future of his time of departure. [ 6 ] Not time travel Sleep . One is very tired, and falls into a deep sleep. When one awakes twelve hours later, it seems from one’s own point of view that hardly any time has passed. Coma . One is in a coma for a number of years and then awakes, at which point it seems from one’s own point of view that hardly any time has passed. Cryogenics . One is cryogenically frozen for hundreds of years. Upon being woken, it seems from one’s own point of view that hardly any time has passed. Virtual . One enters a highly realistic, interactive virtual reality simulator in which some past era has been recreated down to the finest detail. Crystal . One looks into a crystal ball and sees what happened at some past time, or will happen at some future time. (Imagine that the crystal ball really works—like a closed-circuit security monitor, except that the vision genuinely comes from some past or future time. Even so, the person looking at the crystal ball is not thereby a time traveller.) Waiting . One enters one’s closet and stays there for seven hours. When one emerges, one has ‘arrived’ seven hours in the future of one’s ‘departure’. Dateline . One departs at 8pm on Monday, flies for fourteen hours, and arrives at 10pm on Monday.

A satisfactory definition of time travel would, at least, need to classify the cases in the right way. There might be some surprises—perhaps, on the best definition of ‘time travel’, Cryogenics turns out to be time travel after all—but it should certainly be the case, for example, that Gödel counts as time travel and that Sleep and Waiting do not. [ 7 ]

In fact there is no entirely satisfactory definition of ‘time travel’ in the literature. The most popular definition is the one given by Lewis (1976, 145–6):

What is time travel? Inevitably, it involves a discrepancy between time and time. Any traveller departs and then arrives at his destination; the time elapsed from departure to arrival…is the duration of the journey. But if he is a time traveller, the separation in time between departure and arrival does not equal the duration of his journey.…How can it be that the same two events, his departure and his arrival, are separated by two unequal amounts of time?…I reply by distinguishing time itself, external time as I shall also call it, from the personal time of a particular time traveller: roughly, that which is measured by his wristwatch. His journey takes an hour of his personal time, let us say…But the arrival is more than an hour after the departure in external time, if he travels toward the future; or the arrival is before the departure in external time…if he travels toward the past.

This correctly excludes Waiting —where the length of the ‘journey’ precisely matches the separation between ‘arrival’ and ‘departure’—and Crystal , where there is no journey at all—and it includes Doctor . It has trouble with Gödel , however—because when the overall structure of spacetime is as twisted as it is in the sort of case Gödel imagined, the notion of external time (“time itself”) loses its grip.

Another definition of time travel that one sometimes encounters in the literature (Arntzenius, 2006, 602) (Smeenk and Wüthrich, 2011, 5, 26) equates time travel with the existence of CTC’s: closed timelike curves. A curve in this context is a line in spacetime; it is timelike if it could represent the career of a material object; and it is closed if it returns to its starting point (i.e. in spacetime—not merely in space). This now includes Gödel —but it excludes Einstein .

The lack of an adequate definition of ‘time travel’ does not matter for our purposes here. [ 8 ] It suffices that we have clear cases of (what would count as) time travel—and that these cases give rise to all the problems that we shall wish to discuss.

Some authors (in philosophy, physics and science fiction) consider ‘time travel’ scenarios in which there are two temporal dimensions (e.g. Meiland (1974)), and others consider scenarios in which there are multiple ‘parallel’ universes—each one with its own four-dimensional spacetime (e.g. Deutsch and Lockwood (1994)). There is a question whether travelling to another version of 2001 (i.e. not the very same version one experienced in the past)—a version at a different point on the second time dimension, or in a different parallel universe—is really time travel, or whether it is more akin to Virtual . In any case, this kind of scenario does not give rise to many of the problems thrown up by the idea of travelling to the very same past one experienced in one’s younger days. It is these problems that form the primary focus of the present entry, and so we shall not have much to say about other kinds of ‘time travel’ scenario in what follows.

One objection to the possibility of time travel flows directly from attempts to define it in anything like Lewis’s way. The worry is that because time travel involves “a discrepancy between time and time”, time travel scenarios are simply incoherent. The time traveller traverses thirty years in one year; she is 51 years old 21 years after her birth; she dies at the age of 100, 200 years before her birth; and so on. The objection is that these are straightforward contradictions: the basic description of what time travel involves is inconsistent; therefore time travel is logically impossible. [ 9 ]

There must be something wrong with this objection, because it would show Einstein to be logically impossible—whereas this sort of future-directed time travel has actually been observed (albeit on a much smaller scale—but that does not affect the present point) (Hafele and Keating, 1972b,a). The most common response to the objection is that there is no contradiction because the interval of time traversed by the time traveller and the duration of her journey are measured with respect to different frames of reference: there is thus no reason why they should coincide. A similar point applies to the discrepancy between the time elapsed since the time traveller’s birth and her age upon arrival. There is no more of a contradiction here than in the fact that Melbourne is both 800 kilometres away from Sydney—along the main highway—and 1200 kilometres away—along the coast road. [ 10 ]

Before leaving the question ‘What is time travel?’ we should note the crucial distinction between changing the past and participating in (aka affecting or influencing) the past. [ 11 ] In the popular imagination, backwards time travel would allow one to change the past: to right the wrongs of history, to prevent one’s younger self doing things one later regretted, and so on. In a model with a single past, however, this idea is incoherent: the very description of the case involves a contradiction (e.g. the time traveller burns all her diaries at midnight on her fortieth birthday in 1976, and does not burn all her diaries at midnight on her fortieth birthday in 1976). It is not as if there are two versions of the past: the original one, without the time traveller present, and then a second version, with the time traveller playing a role. There is just one past—and two perspectives on it: the perspective of the younger self, and the perspective of the older time travelling self. If these perspectives are inconsistent (e.g. an event occurs in one but not the other) then the time travel scenario is incoherent.

This means that time travellers can do less than we might have hoped: they cannot right the wrongs of history; they cannot even stir a speck of dust on a certain day in the past if, on that day, the speck was in fact unmoved. But this does not mean that time travellers must be entirely powerless in the past: while they cannot do anything that did not actually happen, they can (in principle) do anything that did happen. Time travellers cannot change the past: they cannot make it different from the way it was—but they can participate in it: they can be amongst the people who did make the past the way it was. [ 12 ]

What about models involving two temporal dimensions, or parallel universes—do they allow for coherent scenarios in which the past is changed? [ 13 ] There is certainly no contradiction in saying that the time traveller burns all her diaries at midnight on her fortieth birthday in 1976 in universe 1 (or at hypertime A ), and does not burn all her diaries at midnight on her fortieth birthday in 1976 in universe 2 (or at hypertime B ). The question is whether this kind of story involves changing the past in the sense originally envisaged: righting the wrongs of history, preventing subsequently regretted actions, and so on. Goddu (2003) and van Inwagen (2010) argue that it does (in the context of particular hypertime models), while Smith (1997, 365–6; 2015) argues that it does not: that it involves avoiding the past—leaving it untouched while travelling to a different version of the past in which things proceed differently.

2. The Grandfather Paradox

The most important objection to the logical possibility of backwards time travel is the so-called Grandfather paradox. This paradox has actually convinced many people that backwards time travel is impossible:

The dead giveaway that true time-travel is flatly impossible arises from the well-known “paradoxes” it entails. The classic example is “What if you go back into the past and kill your grandfather when he was still a little boy?”…So complex and hopeless are the paradoxes…that the easiest way out of the irrational chaos that results is to suppose that true time-travel is, and forever will be, impossible. (Asimov 1995 [2003, 276–7]) travel into one’s past…would seem to give rise to all sorts of logical problems, if you were able to change history. For example, what would happen if you killed your parents before you were born. It might be that one could avoid such paradoxes by some modification of the concept of free will. But this will not be necessary if what I call the chronology protection conjecture is correct: The laws of physics prevent closed timelike curves from appearing . (Hawking, 1992, 604) [ 14 ]

The paradox comes in different forms. Here’s one version:

If time travel was logically possible then the time traveller could return to the past and in a suicidal rage destroy his time machine before it was completed and murder his younger self. But if this was so a necessary condition for the time trip to have occurred at all is removed, and we should then conclude that the time trip did not occur. Hence if the time trip did occur, then it did not occur. Hence it did not occur, and it is necessary that it did not occur. To reply, as it is standardly done, that our time traveller cannot change the past in this way, is a petitio principii . Why is it that the time traveller is constrained in this way? What mysterious force stills his sudden suicidal rage? (Smith, 1985, 58)

The idea is that backwards time travel is impossible because if it occurred, time travellers would attempt to do things such as kill their younger selves (or their grandfathers etc.). We know that doing these things—indeed, changing the past in any way—is impossible. But were there time travel, there would then be nothing left to stop these things happening. If we let things get to the stage where the time traveller is facing Grandfather with a loaded weapon, then there is nothing left to prevent the impossible from occurring. So we must draw the line earlier: it must be impossible for someone to get into this situation at all; that is, backwards time travel must be impossible.

In order to defend the possibility of time travel in the face of this argument we need to show that time travel is not a sure route to doing the impossible. So, given that a time traveller has gone to the past and is facing Grandfather, what could stop her killing Grandfather? Some science fiction authors resort to the idea of chaperones or time guardians who prevent time travellers from changing the past—or to mysterious forces of logic. But it is hard to take these ideas seriously—and more importantly, it is hard to make them work in detail when we remember that changing the past is impossible. (The chaperone is acting to ensure that the past remains as it was—but the only reason it ever was that way is because of his very actions.) [ 15 ] Fortunately there is a better response—also to be found in the science fiction literature, and brought to the attention of philosophers by Lewis (1976). What would stop the time traveller doing the impossible? She would fail “for some commonplace reason”, as Lewis (1976, 150) puts it. Her gun might jam, a noise might distract her, she might slip on a banana peel, etc. Nothing more than such ordinary occurrences is required to stop the time traveller killing Grandfather. Hence backwards time travel does not entail the occurrence of impossible events—and so the above objection is defused.

A problem remains. Suppose Tim, a time-traveller, is facing his grandfather with a loaded gun. Can Tim kill Grandfather? On the one hand, yes he can. He is an excellent shot; there is no chaperone to stop him; the laws of logic will not magically stay his hand; he hates Grandfather and will not hesitate to pull the trigger; etc. On the other hand, no he can’t. To kill Grandfather would be to change the past, and no-one can do that (not to mention the fact that if Grandfather died, then Tim would not have been born). So we have a contradiction: Tim can kill Grandfather and Tim cannot kill Grandfather. Time travel thus leads to a contradiction: so it is impossible.

Note the difference between this version of the Grandfather paradox and the version considered above. In the earlier version, the contradiction happens if Tim kills Grandfather. The solution was to say that Tim can go into the past without killing Grandfather—hence time travel does not entail a contradiction. In the new version, the contradiction happens as soon as Tim gets to the past. Of course Tim does not kill Grandfather—but we still have a contradiction anyway: for he both can do it, and cannot do it. As Lewis puts it:

Could a time traveler change the past? It seems not: the events of a past moment could no more change than numbers could. Yet it seems that he would be as able as anyone to do things that would change the past if he did them. If a time traveler visiting the past both could and couldn’t do something that would change it, then there cannot possibly be such a time traveler. (Lewis, 1976, 149)

Lewis’s own solution to this problem has been widely accepted. [ 16 ] It turns on the idea that to say that something can happen is to say that its occurrence is compossible with certain facts, where context determines (more or less) which facts are the relevant ones. Tim’s killing Grandfather in 1921 is compossible with the facts about his weapon, training, state of mind, and so on. It is not compossible with further facts, such as the fact that Grandfather did not die in 1921. Thus ‘Tim can kill Grandfather’ is true in one sense (relative to one set of facts) and false in another sense (relative to another set of facts)—but there is no single sense in which it is both true and false. So there is no contradiction here—merely an equivocation.

Another response is that of Vihvelin (1996), who argues that there is no contradiction here because ‘Tim can kill Grandfather’ is simply false (i.e. contra Lewis, there is no legitimate sense in which it is true). According to Vihvelin, for ‘Tim can kill Grandfather’ to be true, there must be at least some occasions on which ‘If Tim had tried to kill Grandfather, he would or at least might have succeeded’ is true—but, Vihvelin argues, at any world remotely like ours, the latter counterfactual is always false. [ 17 ]

Return to the original version of the Grandfather paradox and Lewis’s ‘commonplace reasons’ response to it. This response engenders a new objection—due to Horwich (1987)—not to the possibility but to the probability of backwards time travel.

Think about correlated events in general. Whenever we see two things frequently occurring together, this is because one of them causes the other, or some third thing causes both. Horwich calls this the Principle of V-Correlation:

if events of type A and B are associated with one another, then either there is always a chain of events between them…or else we find an earlier event of type C that links up with A and B by two such chains of events. What we do not see is…an inverse fork—in which A and B are connected only with a characteristic subsequent event, but no preceding one. (Horwich, 1987, 97–8)

For example, suppose that two students turn up to class wearing the same outfits. That could just be a coincidence (i.e. there is no common cause, and no direct causal link between the two events). If it happens every week for the whole semester, it is possible that it is a coincidence, but this is extremely unlikely . Normally, we see this sort of extensive correlation only if either there is a common cause (e.g. both students have product endorsement deals with the same clothing company, or both slavishly copy the same influencer) or a direct causal link (e.g. one student is copying the other).

Now consider the time traveller setting off to kill her younger self. As discussed, no contradiction need ensue—this is prevented not by chaperones or mysterious forces, but by a run of ordinary occurrences in which the trigger falls off the time traveller’s gun, a gust of wind pushes her bullet off course, she slips on a banana peel, and so on. But now consider this run of ordinary occurrences. Whenever the time traveller contemplates auto-infanticide, someone nearby will drop a banana peel ready for her to slip on, or a bird will begin to fly so that it will be in the path of the time traveller’s bullet by the time she fires, and so on. In general, there will be a correlation between auto-infanticide attempts and foiling occurrences such as the presence of banana peels—and this correlation will be of the type that does not involve a direct causal connection between the correlated events or a common cause of both. But extensive correlations of this sort are, as we saw, extremely rare—so backwards time travel will happen about as often as you will see two people wear the same outfits to class every day of semester, without there being any causal connection between what one wears and what the other wears.

We can set out Horwich’s argument this way:

If time travel were ever to occur, we should see extensive uncaused correlations.
It is extremely unlikely that we should ever see extensive uncaused correlations.
Therefore time travel is extremely unlikely to occur.

The conclusion is not that time travel is impossible, but that we should treat it the way we treat the possibility of, say, tossing a fair coin and getting heads one thousand times in a row. As Price (1996, 278 n.7) puts it—in the context of endorsing Horwich’s conclusion: “the hypothesis of time travel can be made to imply propositions of arbitrarily low probability. This is not a classical reductio, but it is as close as science ever gets.”

Smith (1997) attacks both premisses of Horwich’s argument. Against the first premise, he argues that backwards time travel, in itself, does not entail extensive uncaused correlations. Rather, when we look more closely, we see that time travel scenarios involving extensive uncaused correlations always build in prior coincidences which are themselves highly unlikely. Against the second premise, he argues that, from the fact that we have never seen extensive uncaused correlations, it does not follow that we never shall. This is not inductive scepticism: let us assume (contra the inductive sceptic) that in the absence of any specific reason for thinking things should be different in the future, we are entitled to assume they will continue being the same; still we cannot dismiss a specific reason for thinking the future will be a certain way simply on the basis that things have never been that way in the past. You might reassure an anxious friend that the sun will certainly rise tomorrow because it always has in the past—but you cannot similarly refute an astronomer who claims to have discovered a specific reason for thinking that the earth will stop rotating overnight.

Sider (2002, 119–20) endorses Smith’s second objection. Dowe (2003) criticises Smith’s first objection, but agrees with the second, concluding overall that time travel has not been shown to be improbable. Ismael (2003) reaches a similar conclusion. Goddu (2007) criticises Smith’s first objection to Horwich. Further contributions to the debate include Arntzenius (2006), Smeenk and Wüthrich (2011, §2.2) and Elliott (2018). For other arguments to the same conclusion as Horwich’s—that time travel is improbable—see Ney (2000) and Effingham (2020).

Return again to the original version of the Grandfather paradox and Lewis’s ‘commonplace reasons’ response to it. This response engenders a further objection. The autoinfanticidal time traveller is attempting to do something impossible (render herself permanently dead from an age younger than her age at the time of the attempts). Suppose we accept that she will not succeed and that what will stop her is a succession of commonplace occurrences. The previous objection was that such a succession is improbable . The new objection is that the exclusion of the time traveler from successfully committing auto-infanticide is mysteriously inexplicable . The worry is as follows. Each particular event that foils the time traveller is explicable in a perfectly ordinary way; but the inevitable combination of these events amounts to a ring-fencing of the forbidden zone of autoinfanticide—and this ring-fencing is mystifying. It’s like a grand conspiracy to stop the time traveler from doing what she wants to do—and yet there are no conspirators: no time lords, no magical forces of logic. This is profoundly perplexing. Riggs (1997, 52) writes: “Lewis’s account may do for a once only attempt, but is untenable as a general explanation of Tim’s continual lack of success if he keeps on trying.” Ismael (2003, 308) writes: “Considered individually, there will be nothing anomalous in the explanations…It is almost irresistible to suppose, however, that there is something anomalous in the cases considered collectively, i.e., in our unfailing lack of success.” See also Gorovitz (1964, 366–7), Horwich (1987, 119–21) and Carroll (2010, 86).

There have been two different kinds of defense of time travel against the objection that it involves mysteriously inexplicable occurrences. Baron and Colyvan (2016, 70) agree with the objectors that a purely causal explanation of failure—e.g. Tim fails to kill Grandfather because first he slips on a banana peel, then his gun jams, and so on—is insufficient. However they argue that, in addition, Lewis offers a non-causal—a logical —explanation of failure: “What explains Tim’s failure to kill his grandfather, then, is something about logic; specifically: Tim fails to kill his grandfather because the law of non-contradiction holds.” Smith (2017) argues that the appearance of inexplicability is illusory. There are no scenarios satisfying the description ‘a time traveller commits autoinfanticide’ (or changes the past in any other way) because the description is self-contradictory (e.g. it involves the time traveller permanently dying at 20 and also being alive at 40). So whatever happens it will not be ‘that’. There is literally no way for the time traveller not to fail. Hence there is no need for—or even possibility of—a substantive explanation of why failure invariably occurs, and such failure is not perplexing.

3. Causation

Backwards time travel scenarios give rise to interesting issues concerning causation. In this section we examine two such issues.

Earlier we distinguished changing the past and affecting the past, and argued that while the former is impossible, backwards time travel need involve only the latter. Affecting the past would be an example of backwards causation (i.e. causation where the effect precedes its cause)—and it has been argued that this too is impossible, or at least problematic. [ 18 ] The classic argument against backwards causation is the bilking argument . [ 19 ] Faced with the claim that some event A causes an earlier event B , the proponent of the bilking objection recommends an attempt to decorrelate A and B —that is, to bring about A in cases in which B has not occurred, and to prevent A in cases in which B has occurred. If the attempt is successful, then B often occurs despite the subsequent nonoccurrence of A , and A often occurs without B occurring, and so A cannot be the cause of B . If, on the other hand, the attempt is unsuccessful—if, that is, A cannot be prevented when B has occurred, nor brought about when B has not occurred—then, it is argued, it must be B that is the cause of A , rather than vice versa.

The bilking procedure requires repeated manipulation of event A . Thus, it cannot get under way in cases in which A is either unrepeatable or unmanipulable. Furthermore, the procedure requires us to know whether or not B has occurred, prior to manipulating A —and thus, it cannot get under way in cases in which it cannot be known whether or not B has occurred until after the occurrence or nonoccurrence of A (Dummett, 1964). These three loopholes allow room for many claims of backwards causation that cannot be touched by the bilking argument, because the bilking procedure cannot be performed at all. But what about those cases in which it can be performed? If the procedure succeeds—that is, A and B are decorrelated—then the claim that A causes B is refuted, or at least weakened (depending upon the details of the case). But if the bilking attempt fails, it does not follow that it must be B that is the cause of A , rather than vice versa. Depending upon the situation, that B causes A might become a viable alternative to the hypothesis that A causes B —but there is no reason to think that this alternative must always be the superior one. For example, suppose that I see a photo of you in a paper dated well before your birth, accompanied by a report of your arrival from the future. I now try to bilk your upcoming time trip—but I slip on a banana peel while rushing to push you away from your time machine, my time travel horror stories only inspire you further, and so on. Or again, suppose that I know that you were not in Sydney yesterday. I now try to get you to go there in your time machine—but first I am struck by lightning, then I fall down a manhole, and so on. What does all this prove? Surely not that your arrival in the past causes your departure from the future. Depending upon the details of the case, it seems that we might well be entitled to describe it as involving backwards time travel and backwards causation. At least, if we are not so entitled, this must be because of other facts about the case: it would not follow simply from the repeated coincidental failures of my bilking attempts.

Backwards time travel would apparently allow for the possibility of causal loops, in which things come from nowhere. The things in question might be objects—imagine a time traveller who steals a time machine from the local museum in order to make his time trip and then donates the time machine to the same museum at the end of the trip (i.e. in the past). In this case the machine itself is never built by anyone—it simply exists. The things in question might be information—imagine a time traveller who explains the theory behind time travel to her younger self: theory that she herself knows only because it was explained to her in her youth by her time travelling older self. The things in question might be actions. Imagine a time traveller who visits his younger self. When he encounters his younger self, he suddenly has a vivid memory of being punched on the nose by a strange visitor. He realises that this is that very encounter—and resignedly proceeds to punch his younger self. Why did he do it? Because he knew that it would happen and so felt that he had to do it—but he only knew it would happen because he in fact did it. [ 20 ]

One might think that causal loops are impossible—and hence that insofar as backwards time travel entails such loops, it too is impossible. [ 21 ] There are two issues to consider here. First, does backwards time travel entail causal loops? Lewis (1976, 148) raises the question whether there must be causal loops whenever there is backwards causation; in response to the question, he says simply “I am not sure.” Mellor (1998, 131) appears to claim a positive answer to the question. [ 22 ] Hanley (2004, 130) defends a negative answer by telling a time travel story in which there is backwards time travel and backwards causation, but no causal loops. [ 23 ] Monton (2009) criticises Hanley’s counterexample, but also defends a negative answer via different counterexamples. Effingham (2020) too argues for a negative answer.

Second, are causal loops impossible, or in some other way objectionable? One objection is that causal loops are inexplicable . There have been two main kinds of response to this objection. One is to agree but deny that this is a problem. Lewis (1976, 149) accepts that a loop (as a whole) would be inexplicable—but thinks that this inexplicability (like that of the Big Bang or the decay of a tritium atom) is merely strange, not impossible. In a similar vein, Meyer (2012, 263) argues that if someone asked for an explanation of a loop (as a whole), “the blame would fall on the person asking the question, not on our inability to answer it.” The second kind of response (Hanley, 2004, §5) is to deny that (all) causal loops are inexplicable. A second objection to causal loops, due to Mellor (1998, ch.12), is that in such loops the chances of events would fail to be related to their frequencies in accordance with the law of large numbers. Berkovitz (2001) and Dowe (2001) both argue that Mellor’s objection fails to establish the impossibility of causal loops. [ 24 ] Effingham (2020) considers—and rebuts—some additional objections to the possibility of causal loops.

4. Time and Change

Gödel (1949a [1990a])—in which Gödel presents models of Einstein’s General Theory of Relativity in which there exist CTC’s—can well be regarded as initiating the modern academic literature on time travel, in both philosophy and physics. In a companion paper, Gödel discusses the significance of his results for more general issues in the philosophy of time (Gödel 1949b [1990b]). For the succeeding half century, the time travel literature focussed predominantly on objections to the possibility (or probability) of time travel. More recently, however, there has been renewed interest in the connections between time travel and more general issues in the metaphysics of time and change. We examine some of these in the present section. [ 25 ]

The first thing that we need to do is set up the various metaphysical positions whose relationships with time travel will then be discussed. Consider two metaphysical questions:

Are the past, present and future equally real?
Is there an objective flow or passage of time, and an objective now?

We can label some views on the first question as follows. Eternalism is the view that past and future times, objects and events are just as real as the present time and present events and objects. Nowism is the view that only the present time and present events and objects exist. Now-and-then-ism is the view that the past and present exist but the future does not. We can also label some views on the second question. The A-theory answers in the affirmative: the flow of time and division of events into past (before now), present (now) and future (after now) are objective features of reality (as opposed to mere features of our experience). Furthermore, they are linked: the objective flow of time arises from the movement, through time, of the objective now (from the past towards the future). The B-theory answers in the negative: while we certainly experience now as special, and time as flowing, the B-theory denies that what is going on here is that we are detecting objective features of reality in a way that corresponds transparently to how those features are in themselves. The flow of time and the now are not objective features of reality; they are merely features of our experience. By combining answers to our first and second questions we arrive at positions on the metaphysics of time such as: [ 26 ]

the block universe view: eternalism + B-theory
the moving spotlight view: eternalism + A-theory
the presentist view: nowism + A-theory
the growing block view: now-and-then-ism + A-theory.

So much for positions on time itself. Now for some views on temporal objects: objects that exist in (and, in general, change over) time. Three-dimensionalism is the view that persons, tables and other temporal objects are three-dimensional entities. On this view, what you see in the mirror is a whole person. [ 27 ] Tomorrow, when you look again, you will see the whole person again. On this view, persons and other temporal objects are wholly present at every time at which they exist. Four-dimensionalism is the view that persons, tables and other temporal objects are four-dimensional entities, extending through three dimensions of space and one dimension of time. On this view, what you see in the mirror is not a whole person: it is just a three-dimensional temporal part of a person. Tomorrow, when you look again, you will see a different such temporal part. Say that an object persists through time if it is around at some time and still around at a later time. Three- and four-dimensionalists agree that (some) objects persist, but they differ over how objects persist. According to three-dimensionalists, objects persist by enduring : an object persists from t 1 to t 2 by being wholly present at t 1 and t 2 and every instant in between. According to four-dimensionalists, objects persist by perduring : an object persists from t 1 to t 2 by having temporal parts at t 1 and t 2 and every instant in between. Perduring can be usefully compared with being extended in space: a road extends from Melbourne to Sydney not by being wholly located at every point in between, but by having a spatial part at every point in between.

It is natural to combine three-dimensionalism with presentism and four-dimensionalism with the block universe view—but other combinations of views are certainly possible.

Gödel (1949b [1990b]) argues from the possibility of time travel (more precisely, from the existence of solutions to the field equations of General Relativity in which there exist CTC’s) to the B-theory: that is, to the conclusion that there is no objective flow or passage of time and no objective now. Gödel begins by reviewing an argument from Special Relativity to the B-theory: because the notion of simultaneity becomes a relative one in Special Relativity, there is no room for the idea of an objective succession of “nows”. He then notes that this argument is disrupted in the context of General Relativity, because in models of the latter theory to date, the presence of matter does allow recovery of an objectively distinguished series of “nows”. Gödel then proposes a new model (Gödel 1949a [1990a]) in which no such recovery is possible. (This is the model that contains CTC’s.) Finally, he addresses the issue of how one can infer anything about the nonexistence of an objective flow of time in our universe from the existence of a merely possible universe in which there is no objectively distinguished series of “nows”. His main response is that while it would not be straightforwardly contradictory to suppose that the existence of an objective flow of time depends on the particular, contingent arrangement and motion of matter in the world, this would nevertheless be unsatisfactory. Responses to Gödel have been of two main kinds. Some have objected to the claim that there is no objective flow of time in his model universe (e.g. Savitt (2005); see also Savitt (1994)). Others have objected to the attempt to transfer conclusions about that model universe to our own universe (e.g. Earman (1995, 197–200); for a partial response to Earman see Belot (2005, §3.4)). [ 28 ]

Earlier we posed two questions:

Gödel’s argument is related to the second question. Let’s turn now to the first question. Godfrey-Smith (1980, 72) writes “The metaphysical picture which underlies time travel talk is that of the block universe [i.e. eternalism, in the terminology of the present entry], in which the world is conceived as extended in time as it is in space.” In his report on the Analysis problem to which Godfrey-Smith’s paper is a response, Harrison (1980, 67) replies that he would like an argument in support of this assertion. Here is an argument: [ 29 ]

A fundamental requirement for the possibility of time travel is the existence of the destination of the journey. That is, a journey into the past or the future would have to presuppose that the past or future were somehow real. (Grey, 1999, 56)

Dowe (2000, 442–5) responds that the destination does not have to exist at the time of departure: it only has to exist at the time of arrival—and this is quite compatible with non-eternalist views. And Keller and Nelson (2001, 338) argue that time travel is compatible with presentism:

There is four-dimensional [i.e. eternalist, in the terminology of the present entry] time-travel if the appropriate sorts of events occur at the appropriate sorts of times; events like people hopping into time-machines and disappearing, people reappearing with the right sorts of memories, and so on. But the presentist can have just the same patterns of events happening at just the same times. Or at least, it can be the case on the presentist model that the right sorts of events will happen, or did happen, or are happening, at the rights sorts of times. If it suffices for four-dimensionalist time-travel that Jennifer disappears in 2054 and appears in 1985 with the right sorts of memories, then why shouldn’t it suffice for presentist time-travel that Jennifer will disappear in 2054, and that she did appear in 1985 with the right sorts of memories?

Sider (2005) responds that there is still a problem reconciling presentism with time travel conceived in Lewis’s way: that conception of time travel requires that personal time is similar to external time—but presentists have trouble allowing this. Further contributions to the debate whether presentism—and other versions of the A-theory—are compatible with time travel include Monton (2003), Daniels (2012), Hall (2014) and Wasserman (2018) on the side of compatibility, and Miller (2005), Slater (2005), Miller (2008), Hales (2010) and Markosian (2020) on the side of incompatibility.

Leibniz’s Law says that if x = y (i.e. x and y are identical—one and the same entity) then x and y have exactly the same properties. There is a superficial conflict between this principle of logic and the fact that things change. If Bill is at one time thin and at another time not so—and yet it is the very same person both times—it looks as though the very same entity (Bill) both possesses and fails to possess the property of being thin. Three-dimensionalists and four-dimensionalists respond to this problem in different ways. According to the four-dimensionalist, what is thin is not Bill (who is a four-dimensional entity) but certain temporal parts of Bill; and what is not thin are other temporal parts of Bill. So there is no single entity that both possesses and fails to possess the property of being thin. Three-dimensionalists have several options. One is to deny that there are such properties as ‘thin’ (simpliciter): there are only temporally relativised properties such as ‘thin at time t ’. In that case, while Bill at t 1 and Bill at t 2 are the very same entity—Bill is wholly present at each time—there is no single property that this one entity both possesses and fails to possess: Bill possesses the property ‘thin at t 1 ’ and lacks the property ‘thin at t 2 ’. [ 30 ]

Now consider the case of a time traveller Ben who encounters his younger self at time t . Suppose that the younger self is thin and the older self not so. The four-dimensionalist can accommodate this scenario easily. Just as before, what we have are two different three-dimensional parts of the same four-dimensional entity, one of which possesses the property ‘thin’ and the other of which does not. The three-dimensionalist, however, faces a problem. Even if we relativise properties to times, we still get the contradiction that Ben possesses the property ‘thin at t ’ and also lacks that very same property. [ 31 ] There are several possible options for the three-dimensionalist here. One is to relativise properties not to external times but to personal times (Horwich, 1975, 434–5); another is to relativise properties to spatial locations as well as to times (or simply to spacetime points). Sider (2001, 101–6) criticises both options (and others besides), concluding that time travel is incompatible with three-dimensionalism. Markosian (2004) responds to Sider’s argument; [ 32 ] Miller (2006) also responds to Sider and argues for the compatibility of time travel and endurantism; Gilmore (2007) seeks to weaken the case against endurantism by constructing analogous arguments against perdurantism. Simon (2005) finds problems with Sider’s arguments, but presents different arguments for the same conclusion; Effingham and Robson (2007) and Benovsky (2011) also offer new arguments for this conclusion. For further discussion see Wasserman (2018) and Effingham (2020). [ 33 ]

We have seen arguments to the conclusions that time travel is impossible, improbable and inexplicable. Here’s an argument to the conclusion that backwards time travel simply will not occur. If backwards time travel is ever going to occur, we would already have seen the time travellers—but we have seen none such. [ 34 ] The argument is a weak one. [ 35 ] For a start, it is perhaps conceivable that time travellers have already visited the Earth [ 36 ] —but even granting that they have not, this is still compatible with the future actuality of backwards time travel. First, it may be that time travel is very expensive, difficult or dangerous—or for some other reason quite rare—and that by the time it is available, our present period of history is insufficiently high on the list of interesting destinations. Second, it may be—and indeed existing proposals in the physics literature have this feature—that backwards time travel works by creating a CTC that lies entirely in the future: in this case, backwards time travel becomes possible after the creation of the CTC, but travel to a time earlier than the time at which the CTC is created is not possible. [ 37 ]

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Ehring, Douglas, 1997, “Personal identity and time travel”, Philosophical Studies , 52: 427–33.
Elliott, Katrina, 2019, “How to Know That Time Travel Is Unlikely Without Knowing Why”, Pacific Philosophical Quarterly , 100: 90–113.
Fulmer, Gilbert, 1980, “Understanding time travel”, Southwestern Journal of Philosophy , 11: 151–6.
Gilmore, Cody, 2007, “Time travel, coinciding objects, and persistence”, in Oxford Studies in Metaphysics , Dean W. Zimmerman, ed., Oxford: Clarendon Press, vol. 3, 177–98.
Goddu, G.C., 2003, “Time travel and changing the past (or how to kill yourself and live to tell the tale)”, Ratio , 16: 16–32.
–––, 2007, “Banana peels and time travel”, Dialectica , 61: 559–72.
Gödel, Kurt, 1949a [1990a], “An example of a new type of cosmological solutions of Einstein’s field equations of gravitation”, in Kurt Gödel: Collected Works (Volume II), Solomon Feferman, et al. (eds.), New York: Oxford University Press, 190–8; originally published in Reviews of Modern Physics , 21 (1949): 447–450.
–––, 1949b [1990b], “A remark about the relationship between relativity theory and idealistic philosophy”, in Kurt Gödel: Collected Works (Volume II), Solomon Feferman, et al. (eds.), New York: Oxford University Press, 202–7; originally published in P. Schilpp (ed.), Albert Einstein: Philosopher-Scientist , La Salle: Open Court, 1949, 555–562.
Godfrey-Smith, William, 1980, “Travelling in time”, Analysis , 40: 72–3.
Gorovitz, Samuel, 1964, “Leaving the past alone”, Philosophical Review , 73: 360–71.
Grey, William, 1999, “Troubles with time travel”, Philosophy , 74: 55–70.
Hafele, J. C. and Keating, Richard E., 1972a, “Around-the-world atomic clocks: Observed relativistic time gains”, Science , 177: 168–70.
–––, 1972b, “Around-the-world atomic clocks: Predicted relativistic time gains”, Science , 177: 166–8.
Hales, Steven D., 2010, “No time travel for presentists”, Logos & Episteme , 1: 353–60.
Hall, Thomas, 2014, “In Defense of the Compossibility of Presentism and Time Travel”, Logos & Episteme , 2: 141–59.
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Horacek, David, 2005, “Time travel in indeterministic worlds”, Monist (Special Issue on Time Travel), 88: 423–36.
Horwich, Paul, 1975, “On some alleged paradoxes of time travel”, Journal of Philosophy , 72: 432–44.
–––, 1987, Asymmetries in Time: Problems in the Philosophy of Science , Cambridge MA: MIT Press.
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Kiourti, Ira, 2008, “Killing baby Suzy”, Philosophical Studies , 139: 343–52.
Le Poidevin, Robin, 2003, Travels in Four Dimensions: The Enigmas of Space and Time , Oxford: Oxford University Press.
–––, 2005, “The Cheshire Cat problem and other spatial obstacles to backwards time travel”, Monist (Special Issue on Time Travel), 88: 336–52.
Lewis, David, 1976, “The paradoxes of time travel”, American Philosophical Quarterly , 13: 145–52.
Loss, Roberto, 2015, “How to Change the Past in One-Dimensional Time”, Pacific Philosophical Quarterly , 96: 1–11.
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Markosian, Ned, 2020, “The Dynamic Theory of Time and Time Travel to the Past”, Disputatio , 12: 137–65.
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–––, 2008, “Backwards causation, time, and the open future”, Metaphysica , 9: 173–91.
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–––, 2009, “Time travel without causal loops”, Philosophical Quarterly , 59: 54–67.
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–––, 1997, “The principal paradox of time travel”, Ratio , 10: 48–64.
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–––, 2005, “Time travel and becoming”, Monist (Special Issue on Time Travel), 88: 413–22.
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Simon, Jonathan, 2005, “Is time travel a problem for the three-dimensionalist?”, Monist (Special Issue on Time Travel), 88: 353–61.
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Interesting Time Travel Quotes

February 22, 2015 James Miller Astronomy Lists , Quotes , Time Travel 0

Time travel is a scientific concept in which an object moves between different points in time in the same way as as it would between different points in space. In early 1900’s, Einstein’s theories that space and time form a four-dimensional fabric known as space-time which can be warped as speed or mass is increased did more than anything else to draw serious scientific attention to the field of study, and currently theoretical physicists usually consider the topic in conjunction with quantum physics or wormholes (Einstein–Rosen bridges).

Here are some interesting quotes on a topic full of uncertainty that has sharply divided scientists for decades. But as Stephen Hawking explains, “even if it turns out that time travel is impossible, it is important that we understand why it is impossible.”

H.G. Wells (Writer)

“Man can go up against gravitation in a balloon, and why should he not hope that ultimately he may be able to stop or accelerate his drift along the Time-Dimension , or even turn about and travel the other way.”

Albert Einstein (Theoretical Physicist)

“People like us, who believe in physics, know that the distinction between past, present and future is only a stubbornly persistent illusion.”

Stephen Hawking (Theoretical Physicist)

“Time travel used to be thought of as just science fiction, but Einstein’s general theory of relativity allows for the possibility that we could warp space-time so much that you could go off in a rocket and return before you set out.”

David Deutsch (Physicist)

“I myself believe that there will one day be time travel because when we find that something isn’t forbidden by the over-arching laws of physics we usually eventually find a technological way of doing it.”

Clifford A. Pickover (Writer)

“Today, we know that time travel need not be confined to myths, science fiction, Hollywood movies, or even speculation by theoretical physicists. Time travel is possible . For example, an object traveling at high speeds ages more slowly than a stationary object. This means that if you were to travel into outer space and return, moving close to light speed, you could travel thousands of years into the Earth’s future.”

Martin Ringbauer (Physicist)

“The question of time travel features at the interface between two of our most successful yet incompatible physical theories – Einstein’s general relativity and quantum mechanics. Einstein’s theory describes the world at the very large scale of stars and galaxies, while quantum mechanics is an excellent description of the world at the very small scale of atoms and molecules.”

Michio Kaku (Theoretical Physicist)

“In Einstein’s equation, time is a river. It speeds up, meanders, and slows down. The new wrinkle is that it can have whirlpools and fork into two rivers. So, if the river of time can be bent into a pretzel, create whirlpools and fork into two rivers, then time travel cannot be ruled out.. When you look at the calculation, it’s amazing that every time you try to prove or disprove time travel, you’ve pushed Einstein’s theory to the very limits where quantum effects must dominate. That’s telling us that you really need a theory of everything to resolve this question. And the only candidate is string theory.”

Tim Ralph (Physicist)

“The properties of quantum particles are fuzzy or uncertain to start with. This gives them enough wiggle room to avoid inconsistent time travel situations .. Our study provides insights into where and how nature might behave differently from what our theories predict.”

Brian Greene (String Theorist)

“The basic idea if you’re very, very optimistic is that if you fiddle with the wormhole openings , you can make it not only a shortcut from a point in space to another point in space, but a shortcut from one moment in time to another moment in time.”

Brian Cox (Physicist)

“In General Relativity, you can do it in principle. It’s to do with building these things called wormholes; shortcuts through space and time. But most physicists doubt it. Hawking came up with the ‘chronology protection conjecture’ – physics we don’t yet understand – that means wormholes are not stable.. [re travelling between different dimensions] We look for extra dimensions at the LHC (Large Hadron Collider). You can imagine extra dimensions in space, and that we are living on a sheet of higher dimensional space.”

J. Richard Gott (Astrophysicist)

“Cosmic strings are either infinite or they’re in loops, with no ends. So they are either like spaghetti or Spaghetti Os. The approach of two such [loop] strings parallel to each other, will bend space-time so vigorously and in such a particular configuration that [it] might make time travel possible – in theory. This is a project a super civilization might attempt,” says Gott. “It’s far beyond what we can do. We’re a civilization that’s not even controlling the energy resources of our planet.””

Ronald Mallett (Theoretical Physicist)

“As physicists, our experiments deal with subatomic particles. How soon humans will be able to time travel depends largely on the success of these experiments, which will take the better part of a decade. And depending on breakthroughs, technology, and funding, I believe that human time travel could happen this century… The Grandfather Paradox [where you go back in time and kill your grandfather] is not an issue. In a sense, time travel means that you’re traveling both in time and into other universes. If you go back into the past, you’ll go into another universe. As soon as you arrive at the past, you’re making a choice and there’ll be a split. Our universe will not be affected by what you do in your visit to the past.”

Douglas Adams (Writer)

“If the Universe came to an end every time there was some uncertainty about what had happened in it, it would never have got beyond the first picosecond. And many of course don’t. It’s like a human body, you see. A few cuts and bruises here and there don’t hurt it. Not even major surgery if it’s done properly. Paradoxes are just the scar tissue. Time and space heal themselves up around them and people simply remember a version of events which makes as much sense as they require it to make.”

Margaret Atwood (writer)

“Time is not a line but a dimension, like the dimensions of space. If you can bend space you can bend time also, and if you knew enough and could move faster than light you could travel backward in time and exist in two places at once.”

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20 Brilliant Quotes From Albert Einstein, the Theoretical Physicist Who Became World Famous

Albert einstein, one of the greatest scientists of all time, is best known for his theory of relativity. but he also spoke about social justice, morality and happiness. here's a sample of famous einstein quotes..

This article was originally published on May 19, 2021.

Decades after his death, Albert Einstein's legacy carries on. He is often regarded as the father of modern physics in light of his revolutionary ideas that have shaped our understanding of the universe .

The prolific scientist's rise to celebrity status, however, didn't happen overnight. Unlike many other famous scientists of his time , Einstein lacked a flawless education record and wasn’t well connected in the scientific community. He perfectly embodied the stereotype of a lone genius and typically worked by himself. In 1905, the year he turned 26, Einstein published four groundbreaking papers that laid the foundations for his theory of relativity, E=mc2 and quantum mechanics. But his work largely flew under the radar at the time.

A solar eclipse in 1919 was the watershed moment for his career, when one of his general relativity predictions was confirmed by astronomer Sir Arthur Eddington. Einstein went on to win the Nobel Prize in Physics in 1921 for his explanation of the photoelectric effect — not for relativity, ironically.

Needless to say, Einstein didn't require much of an introduction to the American public by the time he immigrated to the U.S. in 1933 as he sought asylum during Hitler's rise to power. Einstein, who accepted a position at Princeton's Institute for Advanced Study, often used the limelight to share his views on politics, religion and everything in between. Both German-born and Jewish, Einstein was in a unique position to speak out against Nazi Germany and the persecution of Jewish people. The scientist also criticized the racism, discrimination and injustice that he observed in America .

Near the end of his life, Einstein was offered the presidency of Israel — a position he turned down, citing a lack of experience and people skills. He passed away a few years later in 1955 of heart failure. He left behind a lifetime worth of remarkable scientific contributions and social commentary that lives on today.

Einstein is perhaps the most quoted scientist of all time, with remarks about life, morality and social justice being among the most famous Einstein quotes — something he didn't exactly intend for. In 1953 he quipped: "In the past it never occurred to me that every casual remark of mine would be snatched up and recorded. Otherwise I would have crept further into my shell."

Nevertheless, the words he left behind may be the best way to go inside the mind of the legend. Here is a collection of Einstein quotes — from inspiring to thought-provoking — that offer a glimpse into how he saw the world and his work.

Top 20 Albert Einstein Quotes

1. "The most incomprehensible thing about the world is that it is comprehensible."

2. "Where the world ceases to be the scene of our personal hopes and wishes, where we face it as free beings admiring, asking, observing, there we enter the realm of art and science."

3. "A human being is a part of the whole, called by us "universe," a part limited in time and space."

4. "If I were not a physicist, I would probably be a musician. I often think in music. I live my daydreams in music. I see my life in terms of music ... I cannot tell if I would have done any creative work of importance in music, but I do know that I get most joy in life out of my violin."

5. “The greatest scientists are artists as well.”

6. “It occurred to me by intuition, and music was the driving force behind that intuition. My discovery was the result of musical perception.”

7. "I believe in intuitions and inspirations. I sometimes feel that I am right. I do not know that I am." 8. "The supreme task of the physicist is to arrive at those universal elementary laws from which the cosmos can be built up by pure deduction. There is no logical path to these laws; only intuition, resting on sympathetic understanding of experience, can reach them."

9. "Life is like riding a bicycle. To keep your balance you must keep moving."

10. "I believe in one thing — that only a life lived for others is a life worth living."

11. "I am enough of an artist to draw freely upon my imagination. Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world."

12. "The most beautiful experience we can have is the mysterious. It is the fundamental emotion that stands at the cradle of true art and true science. Whoever does not know it and can no longer wonder, no longer marvel, is as good as dead, and his eyes are dimmed."

13. "The important thing is not to stop questioning. Curiosity has its own reason for existing. One cannot help but be in awe when he contemplates the mysteries of eternity, of life, of the marvelous structure of reality. It is enough if one tries merely to comprehend a little of this mystery every day." 14. "My interest in science was always essentially limited to the study of principles ... That I have published so little is due to this same circumstance, as the great need to grasp principles has caused me to spend most of my time on fruitless pursuits."

15. "My passion for social justice has often brought me into conflict with people, as has my aversion to any obligation and dependence I did not regard as absolutely necessary."

16. "Even though the realms of religion and science in themselves are clearly marked off from each other, nevertheless there exist between the two strong reciprocal relationships and dependencies."

17. "Science is international but its success is based on institutions, which are owned by nations. If therefore, we wish to promote culture we have to combine and to organize institutions with our own power and means."

18. "Why does this magnificent applied science which saves work and makes life easier bring us so little happiness? The simple answer runs: Because we have not yet learned to make sensible use of it."

19. "One thing I have learned in a long life: that all our science, measured against reality, is primitive and childlike — and yet it is the most precious thing we have."

20. "All religions, arts and sciences are branches of the same tree. All these aspirations are directed toward ennobling man's life, lifting it from the sphere of mere physical existence and leading the individual towards freedom."

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80 Best Time Travel Quotes in the World With Pictures

April 5, 2024

Time travel has been a subject of fascination and speculation for centuries, capturing the imaginations of writers, scientists, and dreamers alike. From H.G. Wells’ “The Time Machine” to Christopher Nolan’s “Tenet,” the concept of moving through time has been explored in countless works of fiction and non-fiction.

However, even beyond literature and film, time travel has inspired many profound and thought-provoking quotes. Whether they explore the implications of altering the past, the complexities of time itself, or the philosophical implications of such a feat, these quotes offer a glimpse into the fascinating and mysterious world of time travel.

This article will delve into some of the most exciting and insightful time travel quotes that will make you ponder the nature of time itself.

Importance of Time Travel Quotes

How to find your Time Travel Quotes

Top 20 most famous time travel quotes, top 20 time travel quotes that will alter your understanding of time, 10 motivational time travel quotes to lift your spirit, 10 time travel quotes that will motivate you to advance in life, 10 time traveling jokes that will make you think and laugh, 10 time travel quotes by scientists, final thought .

Time travel has been a fascinating subject for generations, inspiring countless works of fiction, movies, and TV shows. The ability to travel through time and witness events from the past or future has captured the imagination of many. Alongside these stories, time travel quotes have also gained popularity, and their importance is often overlooked.

Firstly, time travel quotes provide us with a fresh perspective on time. They encourage us to think beyond our current understanding of time and its limitations. Some of the most famous quotes about time travel, such as “Time is an illusion” by Albert Einstein or “The future’s not set, there is no fate but what we make for ourselves” by Sarah Connor from the Terminator series, challenge our preconceptions about the nature of time and the possibilities that time travel might hold.

Secondly, time travel quotes can be thought-provoking and inspiring. They can challenge our assumptions about what is possible in terms of time travel and other areas of life. For example, “The best way to predict your future is to create it” by Abraham Lincoln encourages us to take control of our lives and shape our destinies. At the same time, “Yesterday is history, tomorrow is a mystery, but today is a gift. That’s why it’s called the present” by Master Oogway in Kung Fu Panda reminds us to live in the present moment and appreciate what we have.

Thirdly, time travel quotes often have deeper meanings that can relate to our personal lives. They can provide us with insight into the human experience, such as “We all have our time machines. Some take us back, they’re called memories. Some take us forward, they’re called dreams” by Jeremy Irons or “The past is a foreign country; they do things differently there” by L.P. Hartley. These quotes help us reflect on our own experiences and remind us that our actions today can shape our future and that of others.

Finally, time travel quotes are a form of cultural expression that can bring people together. They can inspire conversation and encourage us to share our thoughts and ideas about time travel. They can also serve as entertainment, as fans of time travel stories often enjoy quoting their favorite lines and debating their meaning.

They reflect our fascination with the concept of time travel and its possibilities. They can inspire, challenge, and provide insight into the human experience. So, the next time you come across a time travel quote, consider its meaning and how it relates to your life. You might discover a new way of looking at the time.

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Read More: 30 Best Minimalist Small Travel Tattoos

Time travel has always fascinated us; as we have seen in countless movies and books, it can transport us to different eras and places. Whether a journey to the past or a trip to the future, time travel allows us to explore other dimensions and possibilities.

It’s no wonder that time travel quotes are so famous – they capture our imaginations and inspire us to dream big. If you’re looking for time travel quotes, here are some tips to help you get started.

Read books and watch movies about time travel .

The first step in finding your time travel quotes is to immerse yourself in the world of time travel. Read books, and watch movies and TV shows that explore the concept of time travel.

As you read and watch, take note of quotes that resonate with you. Do they inspire you? Do they make you think? Do they make you feel something? These are the quotes you’ll want to remember.

Reflect on your own experiences .

Think about the moments when you’ve felt like you’ve traveled through time. It could be a visit to a historic site that made you feel like you were living in a different era or a glimpse of your childhood home that transported you back in time.

Reflect on these experiences and see if any quotes come to mind. These quotes can be personal and powerful, capturing the essence of your own time travel experience.

Look to the past and the future .

Time travel is all about exploring different eras and possibilities. Don’t limit yourself to a particular period or age when looking for time travel quotes.

Look to the past and the future, and think about the different possibilities that exist. Quotes that capture the spirit of exploration and adventure can be particularly inspiring.

Consider the power of imagination .

Our imaginations often fuel time travel. As you search for time travel quotes, think about the power of imagination and its role in our lives. Quotes that inspire us to dream big and think outside the box can be compelling.

Keep an open mind

Finally, when searching for time travel quotes, keep an open mind. Feel free to explore different genres and styles of writing.

The best time travel quotes are often unexpected and can come from various sources.

Read More: The Best 50 Humorous Camping Quotes Funny

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“The future is something which everyone reaches at the rate of sixty minutes an hour, whatever he does, whoever he is.” – C.S. Lewis.

“The past is always tense, the future perfect.” – Zadie Smith
“Time travel used to be thought of as just science fiction, but Einstein’s general theory of relativity allows for the possibility that we could warp space-time so much that you could go off in a rocket and return before you set out.” – Stephen Hawking.
“Time is a created thing. To say ‘I don’t have time,’ is like saying, ‘I don’t want to.'” – Lao Tzu
“The best thing about time travel is that it teaches you about time, about what has been and what will be.” – Germaine Greer.
“I’m not afraid of dying. I’m afraid of not being here to take care of the people I love.” – Jonathan Safran Foer.
“Time flies over us, but leaves its shadow behind.” – Nathaniel Hawthorne
“Time travel is a fantasy that has been around as long as the imagination itself.” – James Gleick
“Time travel is possible, but you can’t change anything.” – Brian Greene

“Time travel is the greatest adventure of all. It’s like taking a giant step into the unknown, except that you know what’s going to happen.” – Terry Pratchett
“Time travel is a dangerous business, especially if you don’t know what you’re doing.” – Douglas Adams
“The only reason for time is so that everything doesn’t happen at once.” – Albert Einstein
“Time travel is like visiting Paris. You can’t just read the guidebook, you’ve got to throw yourself in and see what happens.” – John Titor
“Time travel may be achieved one day, or it may not. But if it is, it will be by ordinary people, not by the forces of science fiction.” – Paul Davies
“Time travel is possible, but it’s not like in the movies. You can’t just hop in a DeLorean and go back in time.” – Michio Kaku

“Time travel is an escape hatch from reality.” – Philip K. Dick
“Time travel is impossible, because it violates causality.” – Roger Penrose
“Time travel is not just a plot device. It’s a way of exploring the human condition.” – Robert J. Sawyer
“Time travel is like a drug. It can be exhilarating, but it can also be dangerous.” – David Gerrold
“Time travel is a dream that science has not yet made a reality.” – Michio Kaku
“I think that time travel is possible, but it is beyond our current technological capabilities.” – Michio Kaku

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“Time travel is possible, but you can only go forward in time, not backward.” – Stephen Hawking
“Time travel is like visiting Paris. You can’t just read the guidebook; you have to go there and experience it for yourself.” – Aurelio Voltaire

“Time travel may be possible, but it is not possible to change anything that has already happened.” – Brian Cox
“Time travel is the ultimate expression of free will.” – David Gerrold
“The future is already here, it’s just not evenly distributed.” – William Gibson
“The best way to predict your future is to create it.” – Peter Drucker
“Time is a created thing. To say ‘I don’t have time,’ is like saying, ‘I don’t want to.” – Lao Tzu
“Time is the most valuable thing a man can spend.” – Theophrastus

“Time and tide wait for no man.” – Geoffrey Chaucer
“Time is what we want most, but what we use worst.” – William Penn
“Time is the longest distance between two places.” – Tennessee Williams
“Time is a thief, and the future heist is always just around the corner.” – Terry Pratchett
“We all have our time machines. Some take us back; they’re called memories. Some take us forward; they’re called dreams.” – Jeremy Irons
“The future belongs to those who believe in the beauty of their dreams.” – Eleanor Roosevelt
“Your time is limited, don’t waste it living someone else’s life.” – Steve Jobs
“The present changes the past. Looking back, you do not find what you left behind.” – Kiran Desai
“The past is a foreign country; they do things differently there.” – L.P. Hartley, The Go-Between

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“The future is something which everyone reaches at the rate of sixty minutes an hour, whatever he does, whoever he is.” – C.S. Lewis
“We do not remember days; we remember moments.” – Cesare Pavese
“Time is a thief, but he is also a creator.” – Robert Rauschenberg
“The past cannot be changed. The future is yet in your power.” – Mary Pickford
“The only way to do great work is to love what you do. If you haven’t found it yet, keep looking. Don’t settle. As with all matters of the heart, you’ll know when you find it.” – Steve Jobs
“The best way to predict your future is to create it.” – Abraham Lincoln

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“I have learned that if you must leave a place that you have lived in and loved and where all your yesteryears are buried deep, leave it any way except a slow way, leave it the fastest way you can. Never turn back and never believe that an hour you remember is a better hour because it is dead. Passed years seem safe ones, vanquished ones, while the future lives in a cloud, formidable from a distance.” – Beryl Markham.
“The future is not some place we are going to, but one we are creating. The paths are not to be found, but made, and the activity of making them changes both the maker and the destination.” – John Schaar
“I have seen the future and it is very much like the present, only longer.” – Dan Quisenberry
“The future is called ‘perhaps,’ which is the only possible thing to call the future. And the important thing is not to allow that to scare you.” – Tennessee Williams
“The future influences the present just as much as the past.” – Friedrich Nietzsche
“Time travel is just like visiting Paris. You can’t just read the guidebook, you’ve got to throw yourself in, eat the food, use the wrong verbs, get charged double, and end up kissing complete strangers.” – Terry Pratchett
“I love time travel movies. If I could go back in time, I’d watch them all over again.” – Unknown

“Time travel is possible, but only in one direction. Once you’ve gone forward in time, you can’t go back to before you left.” – Woody Allen
“I wish I could go back in time and tell myself not to waste so much time trying to figure out time travel.” – Unknown
“I don’t believe in time travel, but if it ever becomes possible, I’m going back to the 80s to get a better haircut.” – Unknown
“If you could go back in time and change one thing, what would it be? My answer: my hairstyle in middle school.” – Unknown
“I don’t think time travel is possible, because if it was, someone would have already come back and told us how to do it.” – Unknown
“Time travel is like a box of chocolates. You never know what era you’re gonna get.” – Unknown
“I tried to build a time machine, but I ran out of time.” – Unknown
“I’d love to go back in time and meet myself as a kid, just to see the look on my face when I tell myself I’m from the future.” – Unknown
“I’m not afraid of dying; I just don’t want to be there when it happens.” – Woody Allen.

“The concept of time is simply an illusion made up of human memories and experiences.” – Albert Einstein.
“The past, like the future, is indefinite and exists only as a spectrum of possibilities.” – Stephen Hawking.
“Time travel is theoretically impossible, but I wouldn’t want to give it up as a plot gimmick.” – Isaac Asimov.
“Time travel may be achieved one day, or it may not. But if it is, it should not require any fundamental change in world-view, at least for those who broadly share the world view I am presenting in this book.” – David Deutsch.

“The only reason for time is so that everything doesn’t happen at once.” – Albert Einstein.
“Time travel is possible, but it is not possible to travel back before the time machine was invented.” – Michio Kaku.
“Time travel is like visiting Paris. You can’t just read the guidebook; you gotta throw yourself in.” – Richard Curtis.
“Time travel is not just a science fiction concept, but a consequence of Einstein’s theory of general relativity.” – Kip Thorne.

In conclusion, time travel has always been a fascinating concept for humans, and throughout history, many have tried to imagine what it would be like to travel through time. As a result, numerous quotes from famous scientists, authors, and other notable figures reflect on the subject of time travel.

These quotes provide a glimpse into how people think about time and how it relates to our lives. Some quotes inspire us to dream about the possibilities of time travel, while others warn us about the dangers of tampering with the past. Overall, these time travel quotes are a testament to the human imagination and our innate curiosity about the mysteries of time.

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Stephen Hawking’s final book suggests time travel may one day be possible – here’s what to make of it

Research Fellow in the Particle Cosmology Group, School of Physics and Astronomy, University of Nottingham

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“If one made a research grant application to work on time travel it would be dismissed immediately,” writes the physicist Stephen Hawking in his posthumous book Brief Answers to the Big Questions . He was right. But he was also right that asking whether time travel is possible is a “very serious question” that can still be approached scientifically.

Arguing that our current understanding cannot rule it out, Hawking, it seems, was cautiously optimistic. So where does this leave us? We cannot build a time machine today, but could we in the future?

Let’s start with our everyday experience. We take for granted the ability to call our friends and family wherever they are in the world to find out what they are up to right now . But this is something we can never actually know. The signals carrying their voices and images travel incomprehensibly fast, but it still takes a finite time for those signals to reach us.

Our inability to access the “now” of someone far away is at the heart of Albert Einstein’s theories of space and time .

Light speed

Einstein told us that space and time are parts of one thing – spacetime – and that we should be as willing to think about distances in time as we are distances in space. As odd as this might sound, we happily answer “about two and half hours”, when someone asks how far Birmingham is from London. What we mean is that the journey takes that long at an average speed of 50 miles per hour.

Mathematically, our statement is equivalent to saying that Birmingham is about 125 miles from London. As physicists Brian Cox and Jeff Forshaw write in their book Why does E=mc²? , time and distance “can be interchanged using something that has the currency of a speed”. Einstein’s intellectual leap was to suppose that the exchange rate from a time to a distance in spacetime is universal – and it is the speed of light.

The speed of light is the fastest any signal can travel, putting a fundamental limit on how soon we can know what is going on elsewhere in the universe. This gives us “causality” – the law that effects must always come after their causes. It is a serious theoretical thorn in the side of time-travelling protagonists. For me to travel back in time and set in motion events that prevent my birth is to put the effect (me) before the cause (my birth).

Now, if the speed of light is universal (in the vacuum of empty space), we must measure it to be the same – 299,792,458 metres per second – however fast we ourselves are moving. Einstein realised that the consequence of the speed of light being absolute is that space and time itself cannot be. And it turns out that moving clocks must tick slower than stationary ones.

If I were to fly off at incredible speed in a spaceship and return to Earth , less time would pass for me than it would for everyone I left behind. Everyone I returned to would conclude that my life had run as if in slow motion – I would have aged more slowly than them – and I would conclude that theirs had run as if in fast forward. The faster I travelled, the slower my clock would tick relative to clocks on Earth. And if I made the trip at the speed of light, I would return as if I had been frozen in time.

So what if we were to travel faster than light, would time run backwards as science fiction has taught us?

Unfortunately, it takes infinite energy to accelerate a human being to the speed of light, let alone beyond it. But even if we could , time wouldn’t simply run backwards. Instead, it would no longer make sense to talk about forward and backward at all. The law of causality would be violated and the concept of cause and effect would lose its meaning.

Einstein also told us that the force of gravity is a consequence of the way mass warps space and time . The more mass we squeeze into a region of space, the more spacetime is warped and the slower nearby clocks tick. If we squeeze in enough mass, spacetime becomes so warped that even light cannot escape its gravitational pull and a black hole is formed. And if you were to approach the edge of the black hole – its event horizon – your clock would tick infinitely slowly relative to those far away from it.

So could we warp spacetime in just the right way to close it back on itself and travel back in time?

The answer is maybe, and the warping we need is a traversable wormhole . But we also need to produce regions of negative energy density to stabilise it, and the classical physics of the 19th century prevents this. The modern theory of quantum mechanics , however, might not.

According to quantum mechanics, empty space is not empty. Instead, it is filled with pairs of particles that pop in and out of existence. If we can make a region where fewer pairs are allowed to pop in and out than everywhere else, then this region will have negative energy density.

However, finding a consistent theory that combines quantum mechanics with Einstein’s theory of gravity remains one of the biggest challenges in theoretical physics. One candidate, string theory (more precisely M-theory ) may offer up another possibility.

M-theory requires spacetime to have 11 dimensions: the one of time and three of space that we move in and seven more, curled up invisibly small. Could we use these extra spatial dimensions to shortcut space and time? Hawking, at least, was hopeful.

Saving history

So is time travel really a possibility? Our current understanding can’t rule it out, but the answer is probably no.

Einstein’s theories fail to describe the structure of spacetime at incredibly small scales. And while the laws of nature can often be completely at odds with our everyday experience, they are always self-consistent – leaving little room for the paradoxes that abound when we mess with cause and effect in science fiction’s take on time travel.

Despite his playful optimism, Hawking recognised that the undiscovered laws of physics that will one day supersede Einstein’s may conspire to prevent large objects like you and I from hopping casually (not causally) back and forth through time. We call this legacy his “ chronology protection conjecture ”.

Whether or not the future has time machines in store, we can comfort ourselves with the knowledge that when we climb a mountain or speed along in our cars, we change how time ticks.

So, this “ pretend to be a time traveller day ” (December 8), remember that you already are, just not in the way you might hope.

Time travel
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80 Time Travel Quotes That Will Take You To Another Dimension

Detail of famous old medieval astronomical clock in Prague

Going Back In Time Quotes

Famous time travel quotes, time travel quotes by scientists, time machine quotes, pop culture time travel quotes.

The concept of time travel makes things interesting.

Even the greatest mind in history gets lost when it comes to time travel. The absolute truth is still to be found by human beings.

The world is extremely curious to see what is the end result of years of research. Check out this list of inspirational time travel quotes.

You may like these time travel quotes and wonder how today would be different if time traveling existed. These time travel quotes give a subtle insight into a hidden life which many of us would like to see.

Check out 10th Doctor quotes and 11th Doctor quotes as well!

Traveling through time is something everybody would want to do. Here are the best traveling back to the past quotes and time travel quotes you may like.

1. "You can't turn back the clock. But you can wind it up again."

- Bonnie Prudden.

2. "You've got to always go back in time if you want to move forward."

-Snoop Dogg.

3. "I want to go back in time. Not to change anything, but to feel something again."

4. "Do not look back with regret. Past will never come back again."

– Henry Longfellow.

5. "There's going to be moments in life where you are going to want to turn back — that's when you have to go on."

— Ritu Ghatourey.

6. "We cannot go back in time and change the past but we can repent."

– Dieter F. Uchtdorf.

7. "I love going back in time, and the only time you can really do that is on a movie set."

– Tate Taylor.

8. "Life is a learning experience. All you can do is learn from your mistakes, but you can't go back in time."

– Amy Dumas.

9. "You're trying to figure out a way to go back in time and spend more time with your father. Who wouldn't want to do that?"

-Jeremy Piven.

10. "I wish I could freeze time or go back in time and watch my kids grow up all over again because it is just going by too fast."

– Robert Rodriguez.

11. "What happens is, when I perform, I'm somewhere else. I go back in time and get in touch with who I really am."

-Etta James.

12. "But if I could go back in time, I wouldn't do a single thing differently. What if all those things I did were the things that got me here?"

— Cheryl Strayed.

13. "Time and space heal themselves up around them and people simply remember a version of events which makes as much sense as they require it to make."

– Douglas Adams.

14. "If you were falling in love and you could go back in time and relive a day and see the banal things you did that you'd forgotten about, you'd weep, looking at that day."

-Alexander Payne.

15. "Time is an illusion. Lunchtime doubly so."

Time travel is such a wide topic of discussion. Check out these inspirational time travel quotes and some much-loved inspirational travel quotes which you may need!

16. "In a sense, we all are Time Travelers! We are surviving each and every Active Time-Point in this timeline..."

― Aldrin Mathew, 'Time Travel Experiences,' 2017.

17. "Time travel is a philosophical concept, not a scientific one. It is, in fact, as has been pointed out, scientific nonsense."

-Alexie Panshin, 'The Mirror of Infinity,’ 1970.

18. "The bottom line is that time travel is allowed by the laws of physics."

-Brian Greene.

19. "Jade blinked. It was only for a fraction of a second but she could have sworn the house had changed shape."

― Richard J. Ward, 'The Hermit and the Time Machine,' 2014.

20. "There is no difference between Time and any of the three dimensions of Space except that our consciousness moves along it."

-H. G. Wells, 'The Time Machine,' 1895.

21. "Antigravity, teleportation, time travel, energetic DNA evolution, and consciousness transformation could create a world few of us ever even dreamed of."

-David Wilcock, 'The Synchronicity Key' 2013.

22. "I am charging you with the protection of my mother and friends, not to mention keeping my younger self off the Internet. He is as dangerous as Opal."

― Eoin Colfer, 'Artemis Fowl,’2008.

23. "I have a secret project which adds four hours every day to the 24 hours we have. There's a bit of time travel involved."

-Sundar Pichai

24. "One may never get to know how fast the time travels till the one gets in that position to race against the time."

-Neel Preet, 'Voice from the East,' 2016.

25. "It's this simple: Spacetime implies the possibility of time travel."

-Dilip D'Souza, '"How Realistic Is The Idea Of Time Travel?", Live Mint'

26. "When you ghost hunt, you kind of time travel: you get that residue of the past."

- Zak Bagans.

27. "The causality violation device may be doing something else. May have already done it. Something wonderful and terrible."

― Dexter Palmer, 'Version Control,' 2016.

28. "Come here, cat. You wouldn't want to destroy the space-time continuum, would you? Meow. Meow."

-Connie Willis, 'To Say Nothing of the Dog,' 1997.

29. "The truth is, time travel is hard, and people are lazy."

- Margaret Peterson Haddix , 'Redeemed,'2015.

30. "Even if it turns out that time travel is impossible, it is important that we understand why it is impossible."

-Stephen Hawking.

31. "The best evidence that time travel is impossible is the fact that we haven't been invaded by hordes of tourists from the future."

-Guillaume Musso.

32. "Don't time travel into the past, roaming through the nuances as if they can change. Don't bookmark pages you've already read."

-James Altucher.

33. "Our memory is and always will be as good as time travel gets, and in the meantime time will do the travelling for us."

- Maria Konnikova.

34. "Forward time travel is no big deal, being in reality nothing but slow aging."

-Katinka Ridderbos, 'Time,' 2002.

35. "Time travel offends our sense of cause and effect - but maybe the universe doesn't insist on cause and effect."

-Edward M. Lerner.

36. "I like science fiction, I like fantasy, I like time travel, so I had this idea: What if you had a phone that could call into the past?"

-Rainbow Rowell.

Here are quotes about time travel to have a better understanding, including Stephen Hawking time travel quotes. These time travel quotes are inspirational.

37. "If time travel is possible, where are the tourists from the future?"

-Stephen Hawking, 'A Brief History of Time,’ 1988.

38. "I myself believe that there will one day be time travel because when we find that something isn't forbidden by the over-arching laws of physics we usually eventually find a technological way of doing it."

-David Deutsch.

39. "Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world."

― Albert Einstein.

40. "What's important about the model is the idea that the past, present and future are all equally real."

-Dr. Kristie Miller.

41. "Time travel was once considered scientific heresy, and I used to avoid talking about it for fear of being labelled a 'crank.'"

42. "The basic idea if you're very, very optimistic is that if you fiddle with the wormhole openings, you can make it not only a shortcut from a point in space to another point in space, but a shortcut from one moment in time to another moment in time."

43. "Time travel may be possible, but it is not practical."

44. "Around and around they'd go, experiencing just half the time of everyone far away from the black hole. The ship and its crew would be traveling through time,"

-Stephen Hawking, 'The Daily Mail,'.

45. "People like us, who believe in physics, know that the distinction between past, present and future is only a stubbornly persistent illusion."

-Albert Einstein.

46. "If you can bend space, there is a possibility of you twisting space."

-Ron Mallet.

Let's look into some of these inspirational time machine quotes and time travel quotes.

47. "Cameras are the world's first time machines."

― Rebecca McNutt, 'Smog City,'.

48. "We all have our time machines, don't we. Those that take us back are memories...And those that carry us forward, are dreams."

-H.G Wells.

49. "If you ever find yourself coming out of a time machine, run. Run away as fast you can."

― Charles Yu, 'How to Live Safely in a Science Fictional Universe ,'.

50. "Sometimes I wish that I could go into a time machine right now and just look at myself and say, 'Calm down. Things are gonna be fine. Things are gonna be all great. Just relax."

-Tristan Wilds.

51. "Space-ships and time machines are no escape from the human condition."

-Arthur Koestler, 'The Trail of the Dinosaur,'.

52. "To take the time machine, one had to simply lift its case"

― M. Mehwar Anjum, 'The Heist'.

53. "When I finally invent a time machine you will already know about it because I'll have told you a long time ago."

-Dana Gould.

54. "My mind has a time machine; it can travel back to the past when I close my eyes and in my dreams it travels to the future."

― Munia Khan.

55. "You don't need a time machine if you know how to remember."

-Rodman Philbrick, 'Freak the Mighty,'.

56. "I go to the movies whenever I get the chance, because the movie theater is like the woods. It's another place that's like a time machine."

-Carol Rifka Brunt, 'Tell the Wolves I'm Home,'.

57. "Smell is the closest thing human beings have to a time machine"

-Caryl Rivers, 'More Joy Than Rage,'.

58. "Never bring a gun to a fight where the other guy has a time-machine and tomorrow's newspapers."

-James Nicoll.

59. "Live & do everything in such a way so that if you look back in time, you shouldn't say that if had a time machine I would've done it better."

― Immanuel Mohan.

60. I'll just tell you what I remember because memory is as close as I've gotten to building my own time machine.

-Samantha Hunt, 'The Invention of Everything Else,'.

61. "The Time Machine was left deserted on the turf among the rhododendrons."

-H.G Wells, 'The time machine: Chapter 5,'.

62. "If you have a wormhole, then you can turn them into time machines for going backward in time."

-Kip Thorne.

63. "I write about times and places I would visit in a time machine, like ancient Rome or the Wild West."

-Caroline Lawrence.

64. "At my house I have a full-size time machine that I've built over a couple of years... I love looking at people's faces when they walk into my office. They're literally astounded."

-Gregory Nicotero.

65. "When I was in high school, girls made fun of me for liking vampire movies. Now, I'd be their king. Time machine, where are you?"

66. "Just throw me in a time machine, hit random, and wherever I land would be great... Just being thrown into a different time really fascinates me."

-Beau Mirchoff.

Our favorite movies and shows are full of inspirational time travel quotes. Here are some from science fiction you might still love, including Doctor Who time travel quotes.

67. "If either of us ever invent time travel, we agree our first stop will be this meeting today in precisely five seconds."

-Sheldon Cooper, ' The Big Bang Theory ,'.

68. "If you travel back into your own past, that destination becomes your future, and your former present becomes the past, which can't now be changed by your new future."

-Professor Hulk, 'The Avengers: Endgame'.

69. "I got two charges. One to get me here. One to get me home."

-Cable, ' Deadpool 2.'

70. "Wish we could turn back time

To the good old days"

- Twenty one pilots .

71. "Wait a minute, Doc. Are you telling me you built a time machine...Out of a DeLorean?"

-Marty McFly, ' Back to the Future ,'.

72. "The question is not where but when."

-Mikkel Neilson, 'Dark'.

73. "Dormammu, I've come to bargain."

-Doctor Strange, 'Doctor Strange'.

74. "It must be some kind of hot tub time machine"

-Nick, 'Hot Tub Time Machine'.

75. "Love is the one thing we're capable of perceiving that transcends dimensions of time and space."

-Brand, ' Interstellar ' 2014.

76. "The future is not set. There is no fate but what we make."

-Kyle Reese, 'The Terminator'.

77. "Miss Granger, three turns should do it. Good luck."

- Albus Dumbledore, 'Harry Potter and the Prisoners of Azkaban,' 2004.

78. "You just have to come home!"

-Professor X, 'X-Men: Days of future past'.

79. "Shh! Listen! Someone's coming! I think -- I think it might be us!"

- J. K. Rowling, 'Harry Potter and the Prisoner of Azkaban'.

80. "People assume that time is a strict progression of cause to effect, but *actually* from a non-linear, non-subjective viewpoint - it's more like a big ball of wibbly wobbly... time-y wimey... stuff."

-The Doctor, 'Doctor Who' 2007.

Here at Kidadl , we have carefully created lots of interesting family-friendly quotes for everyone to enjoy! If you liked our suggestions for Time Travel Quotes then why not take a look at Perfect Timing quotes and Time Flies quotes ?

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Einstein and Time Travel – His Theories

Cristina Boros April 17, 2016 16 Comments

Einstein and time travel , Einstein theories , theory of relativity

Welcome, and I am very happy to have you here again today 🙂 and talk to you about Albert Einstein and time travel.

Let’s have a look at the scientific part of this subject of time travel. Do you think time travel is just fiction found in movies, books, and games, or could it be a future reality?

We have had some great minds of the century some offered theories, one of them being by the physicist Albert Einstein. So, talking about Einstein and time travel let’s try to understand his theories.

I know it is not a very simple subject but I also think many of you would like to know his ideas, so I will try to explain them as clearly and as simple as I can.

I am not a physicist myself so let’s see in simple terms what Einstein proved with his theories.

The Theory of Special Relativity

First of all, Einstein proved that time is relative; a very different opinion from Newton who claimed that time is absolute. But which one was right? How did Einstein sustain his theory?

His theory says that when you move through space-time at the speed of light, time goes slower for you than for the others.

For example

Travelling with a very fast spaceship, one person would get older by only a few days whereas another who is on the earth, by month or years.

It is said that the faster we travel, the slower time passes.

In 1905, Einstein explained in this theory time-space as a fourth dimension.

To prove this theory, in 1975 Carol Allie made an experiment at the University of Maryland.

Two clocks were synchronized and one was placed on an airplane and another in the laboratory.

When the clock that was placed on the aircraft returned after a few hours of flight, it was seen to be a fraction of a second faster than the clock that remained in the laboratory.

Ok, this is an experiment on a small scale, but what if the clock was placed on a spaceship that flew at the speed of light?

Einstein claims that for a time travel journey to be successful, you would need to be able to travel at the speed of light.

So according to his theory, Einstein claims that traveling at a speed close to the speed of light will slow the time, reaching the speed of light will stop time and if it will be ever possible to pass the speed of light, time will reverse.

General Relativity – Einstein’s Theory

Another theory of this great physicist was that time passes slower for objects in a gravitational field than for an object which is far from such a field.

So here we have black holes, where the gravity is intense.

Kip Thorne (University of California) claimed that wormholes do exist in space and that they are shortcuts to the past. If two wormholes are connected, it could make a passageway to the past or future.

His theory was confirmed in 1919 when during a solar eclipse, astronomers measured the curving of starlight around the Sun.

One more time in 1922, during another sun eclipse confirmed Einstein was right and he became famous worldwide.

Even today flights are based on his theory.

Researchers today say that they have detected gravitational waves coming from two wormholes that crashed together, located at a distance 1.3 billion light years away.

Physicists say that it is difficult to succeed in time travel because, in our world, the laws of physics are not pushed to the limit, but if we could break these rules, time travel would be possible.

Breaking the Rules

Many physicists have tried to violate Einstein’s theories or to ‘break the rules’.

Marian Scully, Lijun Wang, Gunter Nimtz, and Alfons Stalhofen are some of those names who claimed that they have succeeded in violating these theories.

The last two, at the University of Koblenz, transmitted photons at a speed faster than the speed of light, so the photons traveled into the past.

I will not write about each one because it is pure science, physics, and calculus. It would take a mind such as Einstein to understand it.

Based on Einstein theories, the novelist H.G. Wells wrote the novel ‘The time machine’ and physicists think that he was really onto something.

Einstein’s equation E=mc2 proves that time travel into the past is possible theoretically and scientists say that if it is still impossible for us to put this into practice, it doesn’t mean that time travel is impossible.

Stephen Hawkins says about Einstein’s theories, that to travel with a speed faster than light is almost impossible, at least in our world, and if time travel will ever be possible the past will make you stop.

The laws of physics are made not to allow us to change the past.

Now, what to think?

Reading so many different opinions I can understand just one thing. Time travel is possible but we need a more advanced technology to break the laws of physics, to use gravity and travel at the speed of light.

Does the past want to be changed?

I understand that it would be really fascinating if we could do this, but maybe this is too much?

David Lewis gives a good example of this talking about compossibility and the ability to change the past.

It is true that changing past events would have many implications, and practically it is impossible.

Lewis gives as an example

Tim, a man that hates his grandfather wants to travel into the past and kill him.

Would it be possible?

If the grandfather is killed when he is young, this would mean Tim’s parents would not exist, so Tim would also not exist to kill him.

If for example the grandfather normally dies in 1993 and Tim goes back to 1955 to kill him, would he?

Considering the present and that the grandfather should live for Tim to exist, (I will not confuse you more), Tim will be stopped from the past to succeed in killing him.

Lewis’s conclusion and exact quote is:

‘Tim doesn’t but can because he has what it takes ‘(clear shot, daylight) and also he believes that if Tim finally tries to do it, everything will stop him, a bird will fly in front of him, the gun will jam or he will just fall every time he will want to shot his grandfather.

This paradox can also be seen in many films.

So what is your conclusion?

Reading all these theories and ideas, what do you really think?

Is time travel possible only theoretically, or if we push a little bit harder on the laws of nature, can we do

I would like to know your opinion and if you have any questions just ask.

I look forward to hearing from you all and thanks for reading.

For more reading and viewing click below

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Hi Cristina,

I just bumped into your site. That is a very informative and quite interesting article on time travelling.

So many historical personalities delved into the matter, many of them you mention in your post.

Humans are extrordinary creatures when and if they want to so I wouldn’t be surprised if that became a reality in the future.

I hope I am alive to experience it.

thanks for reading and i hope too, one time will see it real. i am the first to try :))i fell we are close

Hello Cristina, appreciate your post and very exited to read about Travel travel theories. There is nothing impossible and if the scientist put full focus on law of nature theories, we can achieve the time travel goal. However this technology should be limitedly used for example to see our earth some 5000, 10000 etc years back and future as well like year 5050. Awesome to imagine this. However all the best! Thanks

thank you for your reading and of course, if will ever be possible time travel should be used for very good reasons:)Thanks again and soon, more articles will bring the news:)

Hi, I loved all the science. I took time to view your video. It was interesting and I learned some information I didn’t know before.

Traveling in time is an intriguing idea. On the one hand I would like to see time travel become a reality. On the other hand changing time could be a problem.

One of my favorite books is The End of Eternity by Isaac Asimov. Thanks, Dave

thank you for reading. yes I think you are absolutely right if it will ever be possible time travel, i don’t think is a good idea for everyone to be able to do it .about the book i will read it and i will tell you my opinion:) thanks again

I just watched 12 monkeys and time travel is one of my favorite genres when watching TV shows and movies. I also watched a documentary of Einsten’s life and I got a gist of his theory of time-space, but still I cannot get the bending and the solar eclipse experiment. But I did enjoy the documentary. Honestly, if I could change the past, I would but my senses are telling that it is very far from reality, and may not happen in this lifetime. That is why I enjoy entertainment about it, so at least I feel contentment. How about you? How do you feel about time travel?

to be honest, I think is possible but not for everyone. It is still researched and i think that if we don’t know yet the way to do it , the ancient civilization sure did. and there are proves that there are time travelers but coming from the future . thanks for reading and I am glad that you enjoy it 🙂

Hi Cristina,I myself believe in time travel and think Einsteins theory is right on.I enjoyed your article very much, thought it was very interesting.Nice job

me too, to be honest, I believe. This is the reason i write about it and I search so many things, I am glad that you enjoyed it and stay around, 🙂 i will write more articles and I hope you will like them:)

I am seriously mind blown right now. The experiment you mentioned back in 1975 is awesome! I would like to know if they have done anymore like this recently with faster planes. I agree that we are bound by the laws of physics, but i really think that we can get over it with technology advancing more and more everyday!. I enjoyed reading this article!

i am happy that you enjoyed reading my article . i think experiments are done every year and the technology advances day by day but as soon as i know about something new… i will write about :)) i am sure in a few year you will have big surprises about faster planes . thanks 🙂

This is the most interesting article I have ever read in my life! Ok so in my opinion, I believe that time travel is possible, maybe not in our lifetime but it’s definitely possible. I mean just look at how far we’ve come over the past 15 years. Now I know that in order to travel to the past or to the future you have to travel faster than the speed of light, which is time in space.

I believe in time that we will eventually be able to live on multiple planets as technology and our resources get more and more advanced. Great article!

I also think in the future we will leave on other planets 🙂 It is also planned to colonize Mars so..it is not too far:)

Do you think not in out life time? Maybe, who knows:)

Thanks for reading and if you want to know more there are plenty of articles on my site so..have a nice time and if I can help , ask me anything:)

Interesting read! I was never 100% sure if I believed in time travel being real, but, I generally do enjoy hearing other stories and theories about that!

As far as Albert Einstein goes, I probably should learn more about him, as he seems to be one of the smartest men to live.

One thing I was not aware of was that the speed at which we travel impacts the speed at which time progresses!

His theory on going at the speed of light has me wondering, would this send one towards the future or the past? And would there be a deciding factor in terms of how far beyond or backwards in time?

I am also somewhat curious to know how he came up with this theory. Do you have an opinion on this?

Hello there:) Arie

In Einstein’s opinion based on his theories time travel can be done in the future is we travel with a speed faster than the speed of light. Not in the past.How he came up with it? He came up with this idea in 1905 , 200 years after Newton wrote about the law of motion.he publishes his theory in 1915, after ten years of studies. So hew exactly came up is a long story and I will write a post very soon stay close:)

GRACIOUS QUOTES

55 thought-provoking time travel quotes (future), top 10 most famous quotes about time travel (best).

“ Time is not a line but a dimension, like the dimensions of space. If you can bend space you can bend time also, and if you knew enough and could move faster than light you could travel backward in time and exist in two places at once.” Margaret Atwood

You've got to always go back in time if you want to move forward. - Snoop Dogg

“Time travel used to be thought of as just science fiction, but Einstein’s general theory of relativity allows for the possibility that we could warp space-time so much that you could go off in a rocket and return before you set out.” Stephen Hawking

Time travel offends our sense of cause and effect but maybe the universe doesn't insist on cause and effect. - Edward M. Lerner

“Time is the most undefinable yet paradoxical of things; the past is gone, the future is not come, and the present becomes the past even while we attempt to define it, and, like the flash of lightning, at once exists and expires.” Charles Caleb Colton

People like us, who believe in physics, know that the distinction between past, present and future is only a stubbornly persistent illusion. - Albert Einstein

“Time travel and teleportation will have to wait. It may take centuries to master these technology . But within the coming decades, we will understand dark matter, perhaps test string theory, find planets which can harbor life , and maybe have Brain 2.0, i.e. our consciousness on a disk which will survive even after we die.” Michio Kaku

Top 16 Quotes About Time Travel that Will Change Your Perspective Of Time

“When we see the shadow on our images, are we seeing the time 11 minutes ago on Mars? Or are we seeing the time on Mars as observed from Earth now? It’s like time travel problems in science fiction. When is now; when was then?” Bill Nye

Time travel will never be impossible forever. - Toba Beta

“Originally, the burden of proof was on physicists to prove that time travel was possible. Now the burden of proof is on physicists to prove there must be a law forbidding time travel.” Michio Kaku

Even if it turns out that time travel is impossible, it is important that we understand why it is impossible. - Stephen Hawking

“In Einstein’s equation, time is a river. It speeds up, meanders, and slows down. The new wrinkle is that it can have whirlpools and fork into two rivers. So, if the river of time can be bent into a pretzel, create whirlpools and fork into two rivers, then time travel cannot be ruled out.” Michio Kaku

Time travel is a thing. It can be very dangerous, and it's also very it's an expensive thing to do. - Don Hertzfeldt

10 Inspiring Time Travel Quotes that Will Warm Your Heart & Soul

“Songs really are like a form of time travel because they really have moved forward in a bubble. Everyone who’s connected with it, the studio’s gone, the musicians are gone, and the only thing that’s left is this recording which was only about a three-minute period maybe 70 years ago.” Tom Waits

If you were falling in love and you could go back in time and relive a day and see the banal things you did that you'd forgotten about, you'd weep, looking at that day. - Alexander Payne

“If I could time travel into the future, my first port of call would be the point where medical technology is at its best because, like most people on this planet, I have this aversion to dying.” Neal Asher

What happens is, when I perform, I'm somewhere else. I go back in time and get in touch with who I really am. - Etta James

“The way that people feel changes everything. Feelings are forces. They cause us to time travel. And to leave ourselves, to leave our bodies. I would be that kind of psychologist who says, ‘You’re absolutely right – there are monsters under the bed.'” Helen Oyeyemi

I want to go back in time. Not to change anything, but to feel something again. - Mercer

“Look at anyone’s bookcase at home, no matter how modest, and you’re going to find a book that contains wisdom or ideas or a language that’s at least a thousand years old. And the idea that humans have created a mechanism to time travel, to hurl ideas into the future, it sort of bookends. Books are a time machine.” Jonathan Nolan

There's a lot of different things that make me want to take photos. A lot of it is, for a long time I've been obsessed with the thought of time travel with my camera. - Shawn Crahan

9 Time Travel Quotes To Help You Move Forward in Life

“People who think about time travel stories sometimes think that going back in time would be fun because you would have all the information you needed to be much more astute than the people there, when the truth is of course you wouldn’t.” Octavia E. Butler

Life is a learning experience. All you can do is learn from your mistakes, but you can't go back in time. - Amy Dumas

“We would go back and maybe not say that thing to our dad that we said, or maybe be a little nicer to someone who we cared about and had a relationship with when we were young. You know, they’re subtle things, but we carry those with us forever. And I think that regret and time travel are intrinsically linked to me.” Colin Trevorrow

Do not look back with regret. Past will never come back again. - Henry Longfellow

10 Funny Quotes About Time Travel that Will Make You Think & Laugh

“Imagination makes us aware of limitless possibilities. How many of us haven’t pondered the concept of infinity or imagined the possibility of time travel? In one of her poems, Emily Bronte likens imagination to a constant companion , but I prefer to think of it as a built-in entertainment system.” Alexandra Adornetto

If time travel is possible, where are the tourists from the future - Stephen Hawking

(MUST READ) It’s Really About Time: The Science of Time Travel

52 Inspirational Quotes on Independence (FREEDOM)
65 Mentoring Quotes to Inspire Success (LEADERSHIP)
65 Inspirational Justice Quotes on Life & Equality (FAIRNESS)
55 Fate Quotes About Love and Life (DESTINY)
69 Blessing Quotes for Life & Success (THANKFUL)
55 Wise Regret Quotes to Help You Move On (LIFE)
53 Most Inspiring Racing Quotes (MOTOR)
77 Short Deep Quotes About Life (INSPIRATION)

Thought-provoking Time Travel Quotes (FUTURE) - Gracious Quotes

61 Inspiring & Funny Homework Quotes (ASSIGNMENT)

61 motivational ability quotes for success (believe).

Did Einstein Warn a Time Will Come When the Rich Control Means of Communication?

The quote constantly spreads across various social media platforms., izz scott lamagdeleine, published april 5, 2024.

About this rating

Many social media posts have paraphrased what Einstein wrote in an essay that was published by the independent socialist magazine “Monthly Review" in May 1949. While the passage Einstein wrote did amount to the same thing as the various paraphrases, he was not writing of something that would happen in the future, but what was happening in 1949.

For years, social media posts have claimed that revered 20th-century physicist Albert Einstein once warned that the time would come when the very rich so controlled the means of communication that it would be almost impossible for ordinary people to make informed decisions. The most recent example we found of the claim, as of this writing, was posted on Facebook on March 20, 2024:

We also found another Facebook post that included Einstein's purported warning from February 2020:

It included a screenshot that supposedly showed a X (formerly known as Twitter) post from two days before, which said:

Albert Einstein warned in 1949 that the time would come when the very rich so controlled the means of communication that it would be almost impossible for ordinary people to make informed decisions and so democracy would then be broken We live in the time Einstein warned about

We found social media posts that attributed the quote to Einstein on TikTok , in addition to other posts made on Facebook and X about the claim. Variants of the claim appeared on these social media platforms. For example, Einstein was attributed as saying, "There will come a time when the rich own all the media, and it will be impossible for the public to make an informed opinion" on Facebook . We also received emails from Snopes readers asking about the claim as well.

Einstein wrote an essay titled "Why Socialism?" for the first issue of the independent socialist magazine "Monthly Review." Published in May 1949, the piece included the following paragraph that said (sentences bolded for emphasis):

Private capital tends to become concentrated in few hands, partly because of competition among the capitalists, and partly because technological development and the increasing division of labor encourage the formation of larger units of production at the expense of smaller ones. The result of these developments is an oligarchy of private capital the enormous power of which cannot be effectively checked even by a democratically organized political society. This is true since the members of legislative bodies are selected by political parties, largely financed or otherwise influenced by private capitalists who, for all practical purposes, separate the electorate from the legislature. The consequence is that the representatives of the people do not in fact sufficiently protect the interests of the underprivileged sections of the population. Moreover, under existing conditions, private capitalists inevitably control, directly or indirectly, the main sources of information (press, radio, education). It is thus extremely difficult, and indeed in most cases quite impossible, for the individual citizen to come to objective conclusions and to make intelligent use of his political rights.

The bolded quotes in the paragraph above do amount to the same thing as the various paraphrases we found on social media — that it would be difficult for people to make informed, objective decisions because sources of information would be controlled by private capitalists.

Crucially, however, Einstein was not writing about something that would happen in the future, but what was happening in 1949. That's a key detail the various paraphrases were wrong about.

As such, we have given the claim — that Einstein once warned that the time would come when the very rich so controlled the means of communication that it would be almost impossible for ordinary people to make informed decisions — a "Mixture" rating.

We've previously fact-checked other quotes that were allegedly said by Einstein, which you can find here .

Allen-Kinross, Pippa. "Einstein Did Argue the Rich Control Communication and This Damages Democracy." Full Fact , 27 Feb. 2020, https://fullfact.org/online/Einstein-warning-rich-control-communication/.

Eisntein, Albert. "Monthly Review | Why Socialism?" Monthly Review , 1 May 2009, https://monthlyreview.org/2009/05/01/why-socialism/.

Lee, Jessica. "Albert Einstein: Quotes He Never Said and Other Facts." Snopes , 15 Feb. 2022, https://www.snopes.com/collections/albert-einstein-collection/.

By Izz Scott LaMagdeleine

Izz Scott LaMagdeleine is a fact-checker for Snopes.

Article Tags

Astrophysicist says he has cracked the code for time travel

C an you imagine going back in time to visit a lost loved one? This heartwrenching desire is what propelled astrophysicist Professor Ron Mallett on a lifelong quest to build a time machine. After years of research, Professor Mallett claims to have finally developed the revolutionary equation for time travel.

The idea of bending time to our will – revisiting the past, altering history, or glimpsing into the future – has been a staple of science fiction for over a century. But could it move from fantasy to reality?

The inspiration: A father's love and a classic novel

Professor Mallett's obsession with time travel and its equation has its roots in a shattering childhood experience. When he was just ten years old, his father, a television repairman who fostered his son's love of science, tragically passed away from a heart attack.

Devastated, the young Mallett sought solace in books. It was H.G. Wells' The Time Machine that sparked a lifelong fascination.

Wells' opening lines became his mantra: "Scientific people know very well that Time is only a kind of Space. And why cannot we move in Time as we move about in the other dimensions of Space?"

This profound question ignited Mallett's scientific journey. He dedicated himself to understanding the nature of time, determined to find a way to revisit the past and see his beloved father once more.

Time travel equation in the hospital

Decades of research into black holes and Einstein's theories of relativity led to the time travel equation.

While hospitalized for a heart condition, Mallett had a revelation. "It turns out that black holes can create a gravitational field that could lead to the creation of time loops that could allow us to go back in time," he explained.

Imagine the fabric of spacetime as a river. While time usually flows in one direction, Mallett theorizes that the immense gravity of a spinning black hole can create whirlpools, where time twists back on itself.

The time machine blueprint

Mallett's vision for a time machine centers on what he calls "an intense and continuous rotating beam of light" to manipulate gravity. His device would use a ring of lasers to mimic the spacetime-distorting effects of a black hole.

"Let's say you have a cup of coffee in front of you. Start stirring the coffee with the spoon. It started to spin, right? That's what a spinning black hole does," explained Mallett.

"In Einstein's theory, space and time are related to each other. That's why it's called space-time. So when the black hole spins, it will actually cause time to shift."

"Eventually, a rotating beam of laser lights can be used as a kind of time machine and cause a time warp that will allow us to go back to the past," said Mallett. Perhaps, what began as a son's wish to see his father one last time might one day transform our understanding of time itself.

Challenges and limitations

The obstacles on the path from time travel equation to machine are immense. Mallett acknowledges the "galactic amounts of energy" needed to power such a device – energy levels far beyond our current capabilities.

The sheer size of a theoretical time machine is also unknown. While Mallett optimistically states, "I figured out how to do it. In theory, it is possible," the reality is that he may not live to see the machine built.

Furthermore, Mallett's theory comes with a significant constraint. "You can send information back, but you can only send it back to the point where you started operating the device."

In this sense, the time machine is like a one-way message service to the past. You can't travel to a point before the machine existed.

Mallet's lifetime of dedication to time travel

Despite the daunting challenges, Mallett's remarkable journey is a testament to the human spirit. Alongside his time travel research, he's led a distinguished academic career, teaching physics at the University of Connecticut .

Now in his seventies, his work has been propelled by an unwavering belief in the possibility of the seemingly impossible.

Equation vs. reality of time travel

Whether Mallett's time machine will ever transcend the realm of theory is uncertain. Skeptics point to the vast technological hurdles and potential paradoxes raised by tampering with time.

Yet, the mere possibility that science might one day unlock the secrets of temporal travel is enough to ignite the imagination. Could we rewrite our regrets, learn from past mistakes, or witness historical events firsthand?

Perhaps Professor Mallett's greatest legacy won't be a time travel equation itself, but the inspiration he provides – a reminder that audacious dreams and unrelenting curiosity have the power to push the boundaries of what we believe is possible.

Read more about Professor Mallett's work here .

More about space-time

As discussed above, space-time, a concept that feels as vast and complex as the universe itself, forms the backbone of our cosmic understanding.

At its core, it blends the dimensions of space and time into a single four-dimensional continuum, challenging our perceptions of reality. This intertwined nature of space and time underpins everything from the motion of planets to the flow of time itself.

Einstein's groundbreaking contribution

Albert Einstein, with his theory of relativity, revolutionized our understanding of space-time. He posited that space and time are not separate entities but are connected in a dynamic relationship affected by mass and energy.

This relationship implies that the presence of a massive object, like a planet or a star, can warp the fabric of space-time around it. It's a concept that turns the notion of a flat, unchanging universe on its head, suggesting that the very structure of the cosmos is malleable.

The warp and weft of the cosmos

Imagine space-time as a vast sheet of fabric. When a heavy object sits on this fabric, it creates a dip or curve. This curvature is what we perceive as gravity.

Planets orbit stars not because they are being "pulled" in a straight line towards them, but because they are following the curved space-time geometry that these massive objects create.

This curvature of space-time is not just a theoretical concept; it's observable and measurable, especially in the presence of extremely massive and dense objects, like black holes.

Gravitational waves: Echoes of cosmic events

One of the most compelling pieces of evidence for the theory of relativity and the dynamic nature of space-time comes from the detection of gravitational waves.

These waves are ripples in the fabric of space-time, generated by some of the most violent and energetic processes in the universe, such as colliding black holes.

Their discovery not only confirmed Einstein's predictions but also opened a new window into observing cosmic events that were previously invisible to us.

Practical impact of space-time

While these concepts might seem distant from daily life, they have real-world applications, particularly in technology. The Global Positioning System (GPS), a technology integral to modern navigation, relies on an understanding of space-time.

Satellites orbiting Earth need to account for the effects of gravitational time dilation -- a consequence of the curvature of space-time -- to provide accurate location data to users on the ground.

In summary, space-time is a framework that shapes our understanding of the universe. From guiding the planets in their orbits to enabling precise navigation on Earth, its effects are both profoundly cosmic and surprisingly practical.

As we continue to explore and understand the intricacies of space-time, we edge closer to unraveling the mysteries of the cosmos, one gravitational wave at a time.

How black holes are linked to time travel

Playing a major role in Dr. Mallett's time machine, black holes exert a gravitational pull so immense that not even light can escape their grasp. This intense gravity fundamentally alters the fabric of space-time around the black hole.

The stronger the gravity, the more pronounced these effects become, leading to what scientists call gravitational time dilation -- a phenomenon where time itself warps, slowing down relative to an observer far from the gravitational pull.

Time dilation explained

At the heart of this phenomenon lies Albert Einstein's theory of General Relativity, which posits that gravity is the result of masses warping the space-time around them.

In the vicinity of a black hole, this warping becomes so extreme that it significantly affects the flow of time.

An observer standing at a safe distance would perceive time to pass much slower for someone closer to the black hole.

This effect intensifies as one approaches the event horizon, the point of no return beyond which the gravitational pull becomes inescapable.

Boundary between time zones

The event horizon of a black hole marks a stark boundary in the universe, where time as we understand it undergoes a dramatic transformation.

To an external observer, objects approaching the event horizon appear to slow down and almost freeze in time, never quite crossing the threshold.

This illusion results from the light from those objects taking longer and longer to reach the observer as the objects move closer to the event horizon, due to the extreme gravitational pull affecting the light's path.

Theoretical implications and observations

This warping of time around black holes is not just a theoretical curiosity. As Dr. Mallett explained previously in this article, it has practical implications for our understanding of the universe. For instance, it plays a crucial role in the behavior of binary systems where one star orbits a black hole.

Moreover, advancements in technology, such as precise atomic clocks and observations from space telescopes, have allowed scientists to measure these effects, further confirming the predictions of General Relativity.

In summary, black holes serve as natural laboratories for testing the limits of our understanding of physics, offering insights into the complex interplay between gravity and the fabric of space-time.

The phenomenon of time dilation near these cosmic behemoths challenges our notions of time and space, inviting us to explore beyond the boundaries of our current knowledge.

As we continue to observe and study these fascinating objects, we inch closer to unraveling the mysteries of the universe.

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Astrophysicist says he has cracked the code for time travel

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Albert Einstein Quotes About Time Travel
Albert Einstein Quotes About Time Travel. All quotes New Quotes (2) God Imagination Inspirational Life Love Science Time Travel more... Life is like riding a bicycle. To keep your balance, you must keep moving. Albert Einstein's letter to his son Eduard (February 5, 1930), as quoted in Walter Isaacson "Einstein: His Life and Universe" (p. 367 ...
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Explore 45 insightful Albert Einstein quotes about time, time travel, and the relativity of time. Each quote is accompanied by a brief explanation, offering a glimpse into Einstein's genius mind.
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Question: How is Einstein's equation (Gμν = 8πG Tμν) actually applied? And how does it support the theory of time travel. Answer: Many physicists refer to this as Einstein's Equations (plural) because it's actually a set of several equations. The symbol Gμν denotes the "Einstein tensor," which is a measure of how much space-time is ...
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Time Travel. First published Thu Nov 14, 2013; substantive revision Fri Mar 22, 2024. There is an extensive literature on time travel in both philosophy and physics. Part of the great interest of the topic stems from the fact that reasons have been given both for thinking that time travel is physically possible—and for thinking that it is ...
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10 Time Travel Quotes That Will Motivate You to Advance in Life. "The past cannot be changed. The future is yet in your power.". - Mary Pickford. "The future is something which everyone reaches at the rate of sixty minutes an hour, whatever he does, whoever he is.".
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Light speed. Einstein told us that space and time are parts of one thing - spacetime - and that we should be as willing to think about distances in time as we are distances in space.
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Time Travel in Einstein's Universe Quotes Showing 1-2 of 2. "If you see an antimatter version of yourself running towards you, think twice before embracing.". ― J. Richard Gott, Time Travel in Einstein's Universe: The Physical Possibilities of Travel Through Time. tags: physics , science , time-travel.
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32. "Don't time travel into the past, roaming through the nuances as if they can change. Don't bookmark pages you've already read." -James Altucher. 33. "Our memory is and always will be as good as time travel gets, and in the meantime time will do the travelling for us." - Maria Konnikova. 34.
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Pin People like us, who believe in physics, know that the distinction between past, present and future is only a stubbornly persistent illusion. - Albert Einstein "Time travel and teleportation will have to wait. It may take centuries to master these technology.But within the coming decades, we will understand dark matter, perhaps test string theory, find planets which can harbor life, and ...
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Decades of research into black holes and Einstein's theories of relativity led to the time travel equation. While hospitalized for a heart condition, Mallett had a revelation.

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