a time travel adventure answer key

Time Travel IELTS Reading Passage with Answers

READING PASSAGE 3

You should spend about 20 minutes on Questions 28-40 which are based on Reading Passage 3 below.

Time Travel

Time travel took a small step away from science fiction and toward science recently when physicists discovered that sub-atomic particles known as neutrinos – progeny of the sun’s radioactive debris – can exceed the speed of light. The unassuming particle – it is electrically neutral, small but with a “non-zero mass” and able to penetrate the human form undetected – is on its way to becoming a rock star of the scientific world.

Researchers from the European Organisation for Nuclear Research (CERN) in Geneva sent the neutrinos hurtling through an underground corridor toward their colleagues at the Oscillation Project with Emulsion-Tracing Apparatus (OPERA) team 730 kilometres away in Gran Sasso, Italy. The neutrinos arrived promptly – so promptly, in fact, that they triggered what scientists are calling the unthinkable – that everything they have learnt, known or taught stemming from the last one hundred years of the physics discipline may need to be reconsidered.

The issue at stake is a tiny segment of time – precisely sixty nanoseconds (which is sixty billionths of a second). This is how much faster than the speed of light the neutrinos managed to go in their underground travels and at a consistent rate (15,000 neutrinos were sent over three years). Even allowing for a margin of error of ten billionths of a second, this stands as proof that it is possible to race against light and win. The duration of the experiment also accounted for and ruled out any possible lunar effects or tidal bulges in the earth’s crust.

Nevertheless, there’s plenty of reason to remain sceptical. According to Harvard University science historian Peter Galison, Einstein’s relativity theory has been “pushed harder than any theory in the history of the physical sciences”. Yet each prior challenge has come to no avail, and relativity has so far refused to buckle.

So is time travel just around the corner? The prospect has certainly been wrenched much closer to the realm of possibility now that a major physical hurdle – the speed of light – has been cleared. If particles can travel faster than light, in theory travelling back in time is possible. How anyone harnesses that to some kind of helpful end is far beyond the scope of any modern technologies, however, and will be left to future generations to explore.

Certainly, any prospective time travellers may have to overcome more physical and logical hurdles than merely overtaking the speed of light. One such problem, posited by René Barjavel in his 1943 text Le Voyageur Imprudent is the so-called grandfather paradox. Barjavel theorised that, if it were possible to go back in time, a time traveller could potentially kill his own grandfather. If this were to happen, however, the time traveller himself would not be born, which is already known to be true. In other words, there is a paradox in circumventing an already known future; time travel is able to facilitate past actions that mean time travel itself cannot occur.

Other possible routes have been offered, though. For Igor Novikov, astrophysicist behind the 1980s’ theorem known as the self-consistency principle, time travel is possible within certain boundaries. Novikov argued that any event causing a paradox would have zero probability. It would be possible, however, to “affect” rather than “change” historical outcomes if travellers avoided all inconsistencies. Averting the sinking of the Titanic, for example, would revoke any future imperative to stop it from sinking – it would be impossible. Saving selected passengers from the water and replacing them with realistic corpses would not be impossible, however, as the historical record would not be altered in any way.

A further possibility is that of parallel universes. Popularised by Bryce Seligman DeWitt in the 1960s (from the seminal formulation of Hugh Everett), the many-worlds interpretation holds that an alternative pathway for every conceivable occurrence actually exists. If we were to send someone back in time, we might therefore expect never to see him again – any alterations would divert that person down a new historical trajectory.

A final hypothesis, one of unidentified provenance, reroutes itself quite efficiently around the grandfather paradox. Non-existence theory suggests exactly that – a person would quite simply never exist if they altered their ancestry in ways that obstructed their own birth. They would still exist in person upon returning to the present, but any chain reactions associated with their actions would not be registered. Their “historical identity” would be gone.

So, will humans one day step across the same boundary that the neutrinos have? World-renowned astrophysicist Stephen Hawking believes that once spaceships can exceed the speed of light, humans could feasibly travel millions of years into the future in order to repopulate earth in the event of a forthcoming apocalypse. This is because, as the spaceships accelerate into the future, time would slow down around them (Hawking concedes that bygone eras are off limits – this would violate the fundamental rule that cause comes before effect).

Hawking is therefore reserved yet optimistic. “Time travel was once considered scientific heresy, and I used to avoid talking about it for fear of being labelled a crank. These days I’m not so cautious.”

Questions 28-33 Do the following statements agree with the information given in Reading Passage 3? In boxes 28–33 on your answer sheet, write

TRUE if the statement agrees with the information FALSE if the statement contradicts the information NOT GIVEN if there is no information on this

28 It is unclear where neutrinos come from. 29 Neutrinos can pass through a person’s body without causing harm. 30 It took scientists between 50-70 nanoseconds to send the neutrinos from Geneva to Italy. 31 Researchers accounted for effects the moon might have had on the experiment. 32 The theory of relativity has often been called into question unsuccessfully. 33 This experiment could soon lead to some practical uses for time travel.

Questions 34–39 Complete the table below. Choose NO MORE THAN THREE WORDS from the passage for each answer. Write your answers in boxes 34–39 on your answer sheet.

Question 40 Choose the correct letter, A, B, C or D. Write the correct letter in box 40 on your answer sheet.

Stephen Hawking has stated that

A Human time travel is theoretically possible, but is unlikely to ever actually occur. B Human time travel might be possible, but only moving backward in time. C Human time travel might be possible, but only moving forward in time. D All time travel is impossible.

Time Travel IELTS Reading Passage Answers

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30. NOT GIVEN

34. past actions

35. inconsistencies

36. Hugh Everett

37. alternative pathway

38. non-existence theory

39. historical identity

Also Check:   ELECTRORECEPTION IELTS Reading Passage & Answers

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Time Travel Reading Answers

Updated On Sep 18, 2023

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Time Travel is a real Reading test passage that appeared in the IELTS. Check out the Time Travel Reading Answers for IELTS below!

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IELTS Academic Reading: Cambridge Official Guide to IELTS Test 4 Reading passage 1; South Pole Adventurer; with best solutions and best explanations

This Academic IELTS Reading post focuses on solutions to  IELTS Cambridge Official Guide to IELTS Test 4 Reading Passage 1 which is titled ‘ South Pole Adventurer’ . This is a targeted post for IELTS candidates who have big problems finding out and understanding Reading Answers in the AC module. This post can guide you the best to understand every Reading answer without much trouble. Finding out IELTS Reading answers is a steady process, and this post will assist you in this respect.

Cambridge Official Guide to IELTS, Test 4: AC Reading Module

Reading Passage 1: Questions 1-13

The headline of the passage: South Pole Adventurer

Questions 1-8: TRUE, FALSE, NOT GIVEN

[In this type of question, candidates are asked to find out whether:

The statement in the question agrees with the information in the passage – TRUE The statement in the question contradicts with the information in the passage – FALSE If there is no information on this – NOT GIVEN

For this type of question, you can divide each statement into three independent pieces and make your way through with the answer.]

Question no. 1: Shirase’s trip to the South Pole is well known to other explorers.

Keywords for the question: Shirase’s trip to the South Pole, well known to other explorers,

The answer can be found in lines 8-12 of paragraph no.1, where the writer says, “ . . ..  Just then, a third man arrived; Japanese explorer Nobu Shirase. However, his part in one of the greatest adventure stories of the 20th century is hardly known outside his own country, even by fellow explorers . .. .. ..”

Here, hardly known outside his own country, even by fellow explorers = NOT well known to other explorers,

So, the statement contradicts with the text.

So, the answer is: FALSE

Question no. 2: Since Shirase arrived in Antarctica, smaller ships have also made the journey.

Keywords for the question: Since Shirase arrived in Antarctica, smaller ships, also made the journey,

In the final few lines of paragraph no. 1, the writer says, “ . . . .. Shirase and his team sailed into Antarctica’s Bay of Whales in the smallest ship ever to try its luck in these dangerous waters .”

Here, smallest ship ever to try its luck in these dangerous waters = Shiarse’s ship was THE FIRST that have made journey in Antarctica,

Question no. 3: Shirase’s original ambition was to travel to the North Pole.

Keywords for the question: Shirase’s original ambition, travel to the North Pole,      

In the beginning of the second paragraph, the writer talks about the primary ambition of Shirase, “Since boyhood Shirase had dreamed of becoming a polar explorer . Like Amundsen, he initially set his sights on the North Pole . . .. . ..”

Here, initially set his sights on the North Pole = his initial/ original ambition was to travel to the North Pole, 

So, the answer is: TRUE   

Question no. 4: Some Japanese officials thought Shirase’s intention to travel to the South Pole was pointless.

Keywords for the question: Some Japanese officials thought, Shirase’s intention, travel to the South Pole, pointless,       

In the second paragraph, have a close look at lines 7-12, “ . ..  In January 1910, Shirase put his plans before Japanese government officials , promising to raise the flag at the South Pole within three years. For many of them , the question wasn’t could he do it but why would it be worth doing? . . .. . . .”  

Here, For many of them = some, Japanese government officials = Japanese officials,

the question . .. . why would it be worth doing? = thought . . ..  pointless,

So, the answer is: TRUE  

Question no. 5: The British team announced their decision to carry out scientific research in Antarctica before Shirase.

Keywords for the question: The British team announced their decision, carry out scientific research in Antarctica, before Shirase,

In this passage, we do not find any information regarding the British team’s announcement about their decision to carry out scientific research in Antarctica before Shirase.

So, the answer is: NOT GIVEN

Question no. 6: Shirase found it easy to raise the money he needed for his trip to the South Pole.

Keywords for the question: Shirase found it easy, raise the money he needed for his trip,

The first few lines of the third paragraph gives us the answer to this question. Here, the writer says, “The response from the government was cool, however, and Shirase struggled to raise funds. . .. . .”

Here, Shirase struggled to raise funds = Shirase did not find it easy to raise the money,

Question no. 7: A previous prime minister of Japan persuaded a scientist to go with Shirase.

Keywords for the question: A previous prime minister of Japan, persuaded a scientist, to go with Shirase,

We find the name of Japan’s former prime minister Shigenobu Okuma in paragraph no. 3 where his contribution to fund Shirase’s expedition is mentioned.

The paragraph also provides information about Shirase hiring a scientist Terutaro Takeda.

However, there is NO INFORMATION about the involvement of a previous prime minister of Japan in persuading a scientist to go with Shirase.

Question no. 8: The weather that slowed down Shirase’s progress to New Zealand was unusually bad for the season.

Keywords for the question: The weather, slowed down Shirase’s progress to New Zealand, was unusually bad for the season, 

In paragraph no. 3, in lines 17-19 the writer mentions, “ .. . . . This was not to be, however. Bad weather delayed the expedition and they didn’t reach New Zealand until 8 February. .. .. .”

However, we do not find any information here which proves that the weather was unusually bad for the season.  

Questions 9-13: Multiple choice questions

[This type of question asks you to choose a suitable answer from the options using the knowledge you gained from the passage. Generally, this question is found as the last question so you should not worry much about it. Finding all the answers for previous questions gives you a good idea about the title.]

Question no. 9: When reporters in New Zealand met Shirase, they were

Keywords for the question: When reporters, New Zealand, met Shirase, they were,

The answer to question no. 9 can be found in paragraph no. 4. Let’s read this short paragraph quickly, “ In New Zealand local reporters were astonished : the ship was half the size of Amundsen’s ship . True, it was reinforced with iron plate and extra wood, but the ship had only the feeblest engine to help force its way through ice. Few doubted Shirase’s courage, but most reckoned the expedition to be ill-prepared as the Japanese had only lightweight sledges for transport across the ice, made of bamboo and wood .”

Here, In New Zealand local reporters were astonished = the reporters in New Zealand were seriously concerned,

the ship was half the size of Amundsen’s ship; the ship had only the feeblest engine; the Japanese had only lightweight sledges for transport across the ice, made of bamboo and wood = poor quality equipment for the expedition,

So, the answer is: A (concerned about the quality of his equipment.)

Question no. 10: What are we told about the captain of the Kainan Maru in the fifth paragraph?  

Keywords for the question: the captain, the Kainan Maru, fifth paragraph,   

In paragraph no. 5, the writer says in lines 7-18, “ . .. .. Nevertheless, on 11 February the Kainan Maru left New Zealand and sailed straight into the worst weather the captain had ever seen. Then, on 6 March, they approached the coastline of Antarctica’s Ross Sea, looking for a place to land. The ice began to close in, threatening to trap them for the winter, an experience no one was likely to survive. With a remarkable piece of seamanship , the captain steered the ship out of the ice and turned north. They would have to wait out the winter in a warmer climate .” 

Here, remarkable piece of seamanship = Shirase’s skill at sailing,  

They would have to wait out the winter in a warmer climate = saved the boat and crew,

So, the answer is: B (His skill at sailing saved the boat and crew.)    

Question no. 11: After Shirase finally reached Antarctica he realised that

Keywords for the question: After Shirase finally reached Antarctica, he realised,    

In lines 9-11 of paragraph no. 7, the author of the text mentions, “ . . .  On 26 January, Shirase estimated there were enough provisions to continue for two more days . . .. . ..”

Here, there were enough provisions to continue for two more days = might not have enough food to get to the South Pole,

So, the answer is: C (he might not have enough food to get to the South Pole.)     

Question no. 12: What is the writer doing in the seventh paragraph?

Keywords for the question: the writer doing, seventh paragraph,   

In paragraph no. 7, the writer describes what conditions Nobu Shirase’s expedition faced, “Shirase set off on 20 January 1912 with Takeda and two dog handlers, leaving two men at the edge of the ice shelf to make meteorological measurements. For a week they struggled through one blizzard after another, holing up in their tents during the worst of the weather. The temperature fell to -25°C, and frostbite claimed some of the dogs. On 26 January, Shirase estimated there were enough provisions to continue for two more days . Two days later, he announced it was time to turn back. Takeda calculated they had reached 80°5 south and had travelled 250 kilometres. The men hoisted the Japanese flag.” 

Here, For a week they struggled through one blizzard after another, holing up in their tents during the worst of the weather. The temperature fell to -25°C, and frostbite claimed some of the dogs = condition of the rough weather,

On 26 January, Shirase estimated there were enough provisions to continue for two more days = condition of the provisions,

So, the answer is: C (describing the conditions that the expedition faced.)     

Question no. 13: What is the writer’s main point in the final paragraph?

Keywords for the question: writer’s main point, final paragraph,  

The final paragraph says, “ . .. . On 3 February, all the men were heading home. The ship reached Tokyo in June 1912 – and Shirase was greeted like a hero despite the fact that he never reached the pole. Nor did he contribute much to science – but then nor did Amundsen , whose only interest was in being first to the pole. Yet Shirase’s expedition was heroic. They travelled beyond 80° south, one of only four teams to have gone so far south at the time. Furthermore, they did it all without the advantages of the other teams and with no previous experience .”

Here, Yet Shirase’s expedition was heroic = incredible achievement, is made = is reached, way = process,

Furthermore, they did it all without the advantages of the other teams and with no previous experience = considering the problems Shirase had to deal with, the achievement was extraordinary,

So, the answer is: A (Considering the problems Shirase had to deal with, his achievement was incredible.)     

© All the texts with inverted commas used in this post are taken from Cambridge Official Guide to IELTS Test 4

Click here for solutions to Cambridge Official Guide to IELTS AC Test 4 Reading Passage 2

Click here for solutions to Cambridge Official Guide to IELTS AC Test 4 Reading Passage 3

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Academic IELTS Reading: Test 2 Passage 1; The Dead Sea Scrolls; with top solutions and best explanations

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5 Unique Tips To Write A Time Travel Story

Writing time travel fiction.

What about time travel keeps us coming back to it in our stories? Some of the earliest time travel stories we know are hundreds of years old. Despite all our technological advancements, we continue to write stories about it and a time travel story. One or more characters either deliberately or accidentally gained the ability to travel into the past or future. Within such a story, they may be able to travel at will, or there are limits on how and when they will travel.

There are three main types of time travel stories that you’ll see today. The first type is preserving the status quo. The second is changing the status quo. The third type is time travel tourism. Preserving the status quo means that the hero needs to ensure that a particular action either does or does not occur. The next one, changing the status quo, is where specific past or present actions must be changed to prevent an undesirable outcome.

First and foremost, time travel gives you the power of what if something had happened differently or hadn’t happened. You can attempt to answer these questions by telling a time travel story. It completely contradicts our world, where we can’t change the past or see the future. We can’t press a reset button and try again. I’m fully supportive of people who want to tell these time travel stories as long as it serves their message. So, stay with me if you want to learn more.

How to write a time travel story?

Time travel stories allow the heroes to fix everything in the present with little to no consequences. It leads to lazy stories resolved with a time machine where everything returns to normal. Every decision we make in the real world has lasting consequences and cannot be undone. Despite this, it’s still important to push for change and improvement.

We’re going to talk about writing stories about time travel. These can be tricky because there are so many things to consider, and all-time paradoxes will drive you nuts. But I want to give you 5 tips that’ll simplify the process and help you decide whether you want to write a story about time travel and how you should execute such a story. Let’s travel!

1. Ask yourself

If you are writing about time travel, you need to ask yourself the question Why? Why are you writing about time travel? Often you don’t necessarily need to incorporate time travel elements into your story instead of writing a story about someone going to the past. Maybe you want to write about historical fiction.

Maybe you want to write a story that’s set back there, and you don’t need anybody from the present day in that setting. Or if you’re writing about somebody going to the future, you’re better off writing a story about a future society or the apocalypse.

Often, writers don’t want to write about time travel so much as they want to write about different periods or different futures. So keep that in mind. If you ever are in the situation where you think you have a good idea for a time travel story, ask yourself:

• Is the time travel necessary?
• What are the characters going to learn from the story?
• Why are they going back or forward in time?
• What is the purpose of all this?

2. Make decisions and device matter

Timeline is one of my favorite time travel novels for various reasons. At the story’s beginning, a team of archaeologists describes a significant battle. Once the time travel story starts unfolding, the macro details of the battle remain largely unchanged. However, the characters were able to use their future knowledge to nudge the past ever so slightly to make the story worth reading. That’s how to write an incredible time travel story, even when the details were already written in stone.

Also, the time travel vehicle or device matters. One major discrepancy between the book (Timeline) and the movie is that the book gave intention to the date and location that was being traveled to in the past.

On the other hand, in the movie, the scientists accidentally open up a wormhole to a random point in history. Then they recruited archaeologists who happened to be studying the castle that was nearby where the wormhole opened. It made the time travel mechanic of the story largely an accident in which the archaeologists happened to arrive shortly before the pivotal battle they were researching.

If the characters can go to any time or place, there should be a reason why they end up at a specific point, even if it isn’t known to the characters at that time. ‘Doctor Who’ does a wonderful job with this, where the TARDIS, the mechanism that they travel through time and space, is sentient and sends the doctor into harm’s way on an episodic basis.

3. Set a goal and give lessons

Characters who make time jumps there they’re going to learn some lessons. Maybe they go to the past and learn to appreciate the future more. Or they go to the future and learn to change themselves before the world becomes a worse place. When you start writing a time travel story. So, set an individual goal to achieve and give some lessons or experience while the characters are on their mission.

Readers don’t like stories where characters know what will happen to them. There was a critically acclaimed space opera, which I never enjoyed for various reasons, but the primary one was that the character knew their future.

All sense of drama about the character surviving was removed when the tension was automatically diffused for every trial. In the early part of the Harry Potter series, I understand why the characters couldn’t use time travel as they might mistake it for the work of an evil wizard. That makes sense. However, once they learned about time travel, they should have used it to their advantage.

4. Establish time travel rules

Another essential thing to remember is to establish the rules of time travel in your story. Who is capable of time travel? How many people can use time travel? Is there a specific device you need, or is there a magic spell? What are the consequences of using time travel? What if they get stuck in time? Can they get stuck in time?

All those different questions need to be asked and answered by the writer before you get into the storytelling. If you don’t understand the rules of time travel in your story, your readers will see through it. They’re going to see it as a fake story they’re not going to get into. You want to sell the idea, and you need to stick to the rules if you do that.

If something happened to a time traveler in the past, then it would have already happened. So when they return to the present and go home and go to sleep, there shouldn’t be a shift in time around them after a given, unspecified, inconsistent amount of time has passed. The biggest thing I’ll say about time travel rules is that they need to remain consistent.

There are plenty of time travel stories that selectively apply. Whatever their self-contained rules are set, the plot can continue and then ignore them whenever it doesn’t affect the plot. Failing to think about the what fully or why of time travel or applying it unravels these stories.

5. Focus on the primary trope

How seriously do you want to take time travel in your story? It’s fine if you want to write a story about time travel and its fun and lighthearted trope. Also, it doesn’t get into the nitty-gritty of how it works. For instance, the story Groundhog Day is about Bill Murray reliving the same day over and over again until he finally becomes a better person. They never explain how time travel works in that story or why it exists. But nobody complains about that because it’s a great story.

However, if you are writing a much more serious and scientific story, you will want to do your research and get your details correct because those types of audiences will be much more critical of you. It’ll take them right out of the story if you get anything wrong.

Types Of Time Travel Stories (Tropes/Prompts)

Once you establish your story rules, you must decide what type of time travel story you will write. There are hundreds of time travel tropes, but none are more important than the message of your story. It’s important to consider setting limits on time travel or what it costs the hero. What could potentially stop you from being able to time travel? Maintain these limits throughout your stories.

Finding the balance between complete freedom and structure in your story is a good idea. Your story may be better served with a degree of logic added. So, it’s essential to consider the sociological implications of time travel in your world and how they affect your characters and the world you’ve built. Here are 4 types of time travel stories/tropes you can use in your story.

• Travel to the past.
• Travel to the future.
• Present is invaded.
• Time travel gimmicks.

Travel to past

The most common one is the story where someone from the present goes back in time to the past. If you are writing this type of story, you’re writing a historical fiction story with a sci-fi twist because you include that time travel.

To write a great historical fiction story, you must research the period you’re writing about. You need to be very knowledgeable about it. What was the technology and the world in general? What kind of expectations did they have for the future? What were the social customs? If you are writing a story about the past, you should find a way to get your readers invested in that time period. One of the best ways to do it is to get the details right and get a good feel for this story world.

Try to present life as it was so your readers could truly appreciate it. One major thing to be aware of when writing stories about characters who go to the past is the butterfly effect. If you have a time traveler who goes to the past, every change they make to this world will have consequences for the future.

If you do have people going into the past, remember that if they kill someone or prevent someone from being killed, that will have consequences in the future. So keep that in mind.

Travel to future

The next type of time travel story is one where characters go from the present into the future, and they may go into the future for various reasons. Maybe they go from the inferno of it because they invented the time machine that can take them into the future. Or, they might have to go to the future to stop some future evil from occurring.

Typically, those stories can get a little foolish because you have to ask yourself some questions. If they must go into the future to stop evil from happening, why don’t they take precautions now? Or why don’t they wait for the future to come to them?

So if you are looking at this type of story, ask yourself: Is it necessary for future time travel to happen? Aside from time travel stories, your main characters go into the past or future.

Present is invaded

Your characters stay in the present, and another character, usually a villain, comes to the present, either from the future or the past, and starts causing problems. The best example of this is Terminator one, an eighties movie that takes place during the eighties. But the main conflict arises because a machine comes from the future to kill Sarah Connor in the present. There isn’t much worldbuilding early on, and we can instantly empathize with Sarah Connor. It’s another technique you can keep in your arsenal.

If you are thinking about time travel stories, be aware that you do have to do the proper worldbuilding for the future or the past, even if you’re bringing one or two characters into that present.

Time travel gimmick

The fourth and final type of time travel story is one where there is a time travel gimmick involved. For instance, in the movie Groundhog Day, the gimmick is that Bill Murray’s character repeats the same day repeatedly until he becomes a better person.

Another example would be the video game, The Legend of Zelda Majora’s Mask. It is about a fantasy world about to be destroyed in three days when the moon crashes into Earth. However, the main character can play the ocarina to go back in time three days and repeat the process until he can finally solve the problem.

We can tell stories based on a world that exists in a hypothetical parallel universe to our own, one that could technically exist. It adds a degree of commitment missing from most time travel stories. Every decision your characters make last within the world that they’re in. Even if they leave that world, the decisions are still there. Also, some people need to live with the consequences of those actions.

When writing a story, sharing your work with a group of people you trust for feedback is essential. It can be beneficial for others to read your work because they can give you ideas for improvement that you had never even considered. So, I encourage you to create a group of people you trust where you can share your stories and ultimately be creative.

What is your all-time favorite time travel story? Let me know in the comments section below.

Learn more from books:

17 Time Travel Romance Books

10 Post Apocalyptic Romance

10 Medieval Romance Novels

15 Historical Romance Books

More writing tips:

10 Tips To Write Male Characters

10 Tips To Write A Woman Character

10 Tips For Naming Characters In A Book

Table of Contents

Pauline Jackson

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Read the passage below and answer the questions 1-13 that follow

Youth Adventure Package

Travel insurance..

Don't let anything spoil your fun! Your vacation is all about exploring, adventure and fun. You want to see new places and try new things.

The Youth Adventure Package is an affordable just in case' backup plan, so you aren't hit with unexpected medical costs while on the adventure of a lifetime. You'll be a long way from home. If you have an unexpected illness or , accidental injury, well be there to help and ensure you get the care you need.

Our emergency travel assistance services are available from anywhere in the world at anytime of the day or night

Even for young healthy travellers, sickness or accidental injury can happen at any time. Charges for hospital stays can be thousands of dollars per day not including doctors' fees and diagnostic services. This easily adds up to a devastating financial loss. You are on the adventure of a lifetime and don't want to be burdened with a medical bill or to pay for lost or stolen luggage.

Travel insurance is intended to cover sudden, unexpected and unforeseeable circumstances. Your plan is comprised of 4 different coverages. For more information, please read the Benefits under each

The Youth Adventure Package does not cover everything. This insurance has some exclusions. You . should read and understand them before you travel. Prior-existing medical conditions may be excluded. Any medical condition you are aware of prior to the effective date of coverage, whether diagnosed or not, may not be covered. Sickness or accidental injury that occurs as a result of the use of alcohol or illegal drugs is not covered.

We are dedicated to protecting you privacy. Your medical history will be collected when required and will only be used or disclosed for the purpose of adjudicating the claim.

Yes you can. Just call your agent no sooner than 7 days prior to the expiry of your policy. You can purchase an extension if you are in good health and have not filed any claims on the policy.

You are covered for any country outside of the USA. However, transit for 5 days only is allowed through the USA

Reading Passage 2

Read the passage below and answer the questions 14-27 that follow

DIVING: TAKE THE PLUNGE

Have you always wanted to learn to dive?

Getting a Diving Certificate will be one of the most exciting experiences of your life as you learn how to explore a new world underwater!

Here's the 10-step path to becoming a certified diver:

STEP 1: Decide you really want to do it.

STEP 2 : Find a dive store and dive instructor you like.

STEP 3: Discuss how you will complete your open-water certification: meeting weekly for classroom and pool sessions, weekend classes, home study, class trip for your open-water dives, and more.

STEP 4: With your instructor, decide on a plan that best fits your schedule.

STEP 5: Put on a mask, a snorkel and a pair of fins. These are the basic items of personal equipment that need to be fitted to you by a dive store professional.

For reasons of safety and comfort, we recommend that you buy dive equipment only at a dive store.

STEP 6: Be enthusiastic. An important part of your training involves going back to the classroom and learning about the dive environment, physics and safety practices.

STEP 7: Get wet! Your first dives will take place in a swimming pool. Be prepared for your first breath on a regulator (breathing apparatus) under water!

STEP 8: Go diving Your open-water training dives provide the opportunity to practise the skills you learned in your classroom and pool work!

STEP 9: Use your 'C-card' now that you’re a certified diver! Only card-carrying divers can buy scuba life-support equipment. We also encourage you to begin right now selecting your personal equipment, especially a regulator, buoyancy compensator and dive computer. Having your own equipment will make you safer and more comfortable under water.

STEP 10: Go for more. Your certification is really just the beginning. You still need to serve a diving internship with your instructor and other experienced divers. Sign up for more training or dives under supervision as soon as you can

FEAR NO MORE

It’s natural to be scared at first, but statistics show scuba diving is not particularly dangerous. It is estimated that there are 2.4 million divers and 17 million dives made in the U.S. per year. Divers Alert Network, the leading safety organisation lor divers. reported only 85 fatalities in the past year. Most of us find that as our ability increases, our fears decrease. The risks in scuba diving, while real, can all be reduced significantly by what you do for your own safely. Here are some of the most common fears of new scuba divers.

It’s understandable if you mistrust your scuba regulator. But mechanical failure of your breathing equipment is highly unlikely. A regulator is simple, strong and designed so that if it does fail, it delivers more air than you need, not less. You will also have an extra breathing system, and so will your diving buddy. Keep an eye on your air gauges and time. If you are running out of air you will find that you have to suck harder to breathe. You will still have time to ascend slowly, even if you have to hold your breath. If you stay above 60 feet and stay out of caves and wrecks — good advice for all new divers — there is no reason to be afraid of running out of air under water.

“The bends’* is the decompression sickness most people associate with diving, but in fact it is almost preventable. Divers most often get the bends by going too deep and coming up too quickly. It is not a serious risk if you stay above 60 feet. A safety stop of three minutes at 15 feet is a wise precaution. Cases of the bends do occur rarely, but the sickness is normally treatable.

Most fish ignore you or swim away. They have very narrow diets and eat only what they are accustomed to; however, sometimes sharks have been known to make attacks on humans. Even here, there is evidence that the shark mistakes a human for his regular meal, a seal or sea-lion, and shark attacks are very rare. In the presence of sharks, remain calm. Don't annoy sharks by poking at them. Almost all fish will leave you alone if you do the same to them.

Fear can sometimes overwhelm the intellect and leaves some people paralysed. The best prevention is training. You will be taught the correct response to danger. When you practise the response, it will be there when you need it. When you know just what to do, you're much less likely to lose self-control. And experience — simply diving again and again — reduces the general anxiety level that is natural when diving is still new. When you realise you are not helpless, your fears are likely to disappear

Reading Passage 3

Read the passage below and answer the Questions 28-40 that follow.

Slow Pood is an international grass roots movement dedicated to preserving the cultural heritage of good food. It started as a humorous protest against the spread of 7 fast food around the world and has developed into a major advocate for the world's unique food products. The movement's logo is a snail. Since being founded in 1986 the

Slow Food snail has crept from its home in Italy to 45 other countries around the world and now boasts over 650,000 members. The movement challenges the loss of flavour resulting from the industrialisation of food and agriculture. Its approach is 'eco-gastronomic'. Slow Food is committed to compiling and distributing information about local foods, drink and culture. Its purpose is to preserve endangered foods, encourage bio-diversity, and support small-scale producers of ethnic and local products around the world.

Modern agri-business has given the world cheap food with little taste, produced at a high cost to the environment. Slow Food has been instrumental in developing initiatives to revive products that take time and craftsmanship to create and which are threatened by global corporate practices. Protecting traditional local products also means safeguarding the people and ecosystems involved in their manufacture. It also provides incentives for the pursuit of production

methods which are healthier for taste, the environment and the agricultural economy.

Statistics on the loss of biodiversity in our food chain are alarming. In less than a century

over 300,000 plant species have disappeared — one plant species disappears every six hours. Today less than 30 varieties of plant feed 95% of the world's population. In Europe, half the breeds of domestic livestock became extinct during the course of the twentieth century. The crisis over mad cow disease and the ongoing debate over genetically modified food have given Slow Food,

with its emphasis on organic methods, unexpected political influence.

In the space of a few years, Slow Food has become a major lobbying force in the European Union on agriculture and trade policy. Agri-business practices that have become dominant worldwide are geared to production in quantity. This is a carryover from agricultural policies set in the 1950s in Europe, when hunger from the war was still a vivid memory. At that time, when the goal was self sufficiency, farmers received subsidies according to the amounts they produced. There was and still is no reward for quality. Two generations ago, the average European family spent about one half of its income on food. Today it spends about 15 per cent. Surveys conducted by Slow Food show that a large majority of Italians would be willing to pay up to 20 per cent more for food in order to

guarantee its quality, especially given recent food scares and scandals.

As national boundaries disappear in Europe and become more open around the world, food has emerged as an important source of identity. Slow Food's position on globalisation is that it has the potential to help as well as harm the small food producer. On the one hand, globalisation has allowed multinational corporations to extend their reach to virtually every comer of the world. However, rather than being afraid of the fast food giants, Slow Food is attempting to offer an alternative choice of "virtuous globalisation" by choosing to focus on quality and helping the small, local producer to access the global market.

The Slow Food organisation had to find ways to ensure its own economic viability.

An initial strategy to generate income through publishing led to a number of food guides that were quickly successful Some of the most popular of these feature restaurants serving authentic, local foods at local prices. Numerous and varied initiatives have sprung up since. The popular quarterly magazine, 'SLOW', features articles about food culture around the world. Italy's largest food show, the 'Salon de Gusto', sponsored by the Slow Food movement, provides an international market to hundreds of small producers whose goods, until recently, rarely left their village or region. Now there is even 'slow travel'. A growing number of tour operators in Italy, France, Australia and India subscribe to the movement, promoting "cultural and educational journeys using food and the people that produce it as the learning medium." 'Slow cities' are entire communities dedicated to improving the quality of life for their citizens through environmentally sound, culturally-aware, eco-gastronomic policies and activities.

Another significant initiative of Slow Food is the Ark of Taste, a database of endangered species of edible plants and domestic animals worldwide. Commissions have been set up in many countries to seek out and catalogue new products. So far, 800 products from 26 countries have been figuratively brought onboard the Ark in an attempt to save them. The Ark of Taste has become an international project and a resource for agricultural biodiversity around the world.

So, a movement that began as a humorous protest against fast food has, in its own organic way, evolved into a versatile and intelligent advocate for the protection of the environment. The best response to global forces challenging the ability to enjoy our food and our lives begins, according to the Slow Food movement, 'at the table'. We are invited to slow down, appreciate the flavours of food and drink, and cultivate the art of living. Fast food isn't likely to disappear, but Slow Food seems to be here to stay as well. Its message is getting through — encouraging a pleasure-loving environmentalism as an alternative to the highspeed pace of the fast-food world. From its humble beginnings, Slow Food now includes a global network of people capable of generating ideas, and programs to defend the right to a responsible

form of pleasure, respectful of cultural diversity and available to all.

Questions 1-5

Which accommodation would you choose for each of the requirements below?

Choose the correct letter (A-E) from the list above.

1. A B C D E You want accommodation close to the ferry boat terminal

2. A B C D E You are looking for the least expensive place to stay

3. A B C D E You have heard that the best spots are on the south coast

4. A B C D E You want to be sure to have a good view from your room

5. A B C D E You like the idea of a big breakfast

Questions 6-10

Look at the travel insurance notice on the following page. Choose the most suitable heading for each of the Frequently Asked Questions ( B-F ) from the list ( i-x ) below

         Part A   viii

            6. i ii iii iv v vi vii viii ix x Part B

          7. i ii iii iv v vi vii viii ix x Part C

          8. i ii iii iv v vi vii viii ix x Part D

          9. i ii iii iv v vi vii viii ix x Part E

          10. i ii iii iv v vi vii viii ix x Part F  

Questions 11-13

Look at the travel insurance notice on the following page.

Using NO MORE THAN THREE WORDS  from the passage    answer each of these questions.

What item is covered in addition to health and medical expenses?

Accidental injury not covered if a person use _______ 

What is special about the coverage for the United States? 

Questions 14-19

Using NO MORE THAN THREE WORDS FROM THE PASSAGE answer the following questions.

what THREE pieces of personal equipment do you need to buy before starting the course?

Why should you buy your equipment from a dive store?

Name ONE topic studied in the classroom. 

What must you show before being allowed to buy scuba diving equipment?

What thing can make you feel more comfortable and safer by possessing it? 

What thing do you need to do with instructor and other experienced divers after being certified? 

Questions 20-23

The passage Fear No More’ on the next page has 5 paragraphs (A-E) .

Choose the most suitable headings for paragraphs B to E from the list (i-ix) below.

EXAMPLE : (ix) Diving statistics

20. i ii iii iv v vi vii viii Paragraph B 21. i ii iii iv v vi vii viii Paragraph C

22. i ii iii iv v vi vii viii Paragraph D

23. i ii iii iv v vi vii viii Paragraph E

Questions 24-27

Complete the notes below using NO MORE THAN THREE WORDS  from  the passage  for each answer.

Dive with a buddy.

Check your gauges so you don’t run out of air.

Dive no deeper than until you feel comfortable.

Don’t as mind Make a 3-minute safety stop at 15 feet.

If you see a shark Avoid splashing, kicking or poking at fish.

Visualise emergencies and - your responses. Experience gives you confidence.

Questions 28-31

The passage “Slew Food’ has 8 paragraphs (A-H) . In which paragraph can the information below be found?

28. A B C D E F G H a catalogue of domestic animal* at risk of disappearing 29. A B C D E F G H statistics on the loss of variety in agricultural species 30. A B C D E F G H  initiatives to ensure the financial survival of the organisation 31. A B C D E F G H information on the food budget of an average family

Question 32

Which of the following does the Slow Food Movement NOT promote?

The first one has been done for you. Indicate the letters of the remaining TWO .

Questions 33-38

Choose ONE phrase from the list (A-H) that matches each of the expressions below. There are more phrases than expressions so you will not use all of them. The first one has been done for you as an example.

33. A B C D E F G H slow travel 

34. A B C D E F G H Ark of Taste  

35. A B C D E F G H virtuous globalisation                                  

36. A B C D E F G H Salon de Gusto                     

37. A B C D E F G H agri-business  

38. A B C D E F G H SLOW

Questions 39-40

Answer the following questions using NO MORE THAN THREE WORDS from  the passage .

Following which crisis did the Slow Food movement become a political force?

This movement was started as a reaction against what?

Search form

Adventure travel.

Check out this brochure with some of the most exciting adventure holidays around the world and improve your reading skills. Are you ready for this?

Instructions

Do the preparation exercise first. Then read the text and do the other exercises.

Preparation

Time for an adventure?

Are you a bit bored with your nine-to-five routine? Have a look at our exciting range of holidays and decide what type of adventure you’d like.

Activity holidays

Our activity holidays are for everyone, people who love danger or who just like sports. We have a huge variety of water, snow or desert holidays. We’ll take you SCUBA diving in the Red Sea or kayaking and white water rafting in Canada. If you prefer snow, you can try skiing or snowboarding in the Alps or even igloo-building. For those who like warmer weather, we also have sandboarding (the desert version of skateboarding) or camel safaris.

Polar expeditions

Take a cruise to Antarctica or the northern Arctic; explore a land of white natural beauty and wonderful wildlife. Our experts will explain everything about the two poles as you watch the penguins in Antarctica or whales and polar bears in the Arctic. There's no greater adventure than travelling to the ends of the earth. A once-in-a-lifetime experience!

Cultural journeys

Our cultural journeys will help you discover ancient civilisations: India, Thailand, Egypt and many more. Visit temples, palaces and ancient ruins – just remember to bring your camera! Get to know local ways of life by exploring markets, trying exotic foods and meeting local people.

Trekking tours

We have trekking holidays to famous places such as Machu Picchu or the Everest Base Camp Trek, as well as some nearer to home in the Highlands of Scotland. You don’t need to be very sporty, just fairly fit. You’ll have a great time enjoying nature with a group of new friends. Some of the holidays include camping, but we’ll transport the tents for you!

Wildlife holidays

We organise small-group tours to get closer to nature in Africa, Asia or South America. Go on safari in Africa and watch lions and giraffes. Meet the famous turtles of the Galapagos Islands. Look for tigers in India, or take an elephant safari in Sri Lanka. We use local guides and stay in a range of accommodation, from tents to tree houses.

Check your understanding: grouping

Check your understanding: multiple selection, worksheets and downloads.

What's the best holiday you have ever had? Where did you go? What did you do?

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Time travel facts for kids

Time travel is the idea of going back in time to the past or forward to the future. We always travel forward, to the future. Time travel to the past is not known to be possible, but it is much used in fiction. The Time Machine (1895) by H. G. Wells was one of the first and most famous stories of time travel. Much later, the American movie " Back to the Future " tells a fictional story about a professor who builds a machine that can take people into the future or back in the past.

The popular British TV program Doctor Who is about an alien who has adventures by time travelling. Another TV show about time travel is the series Charmed . Instead of using machines and science, this one uses magic to go to other times and places.

Some series that are not mainly about time travel have episodes about it, for example Star Trek and Stargate and The Flash .

Related pages

• General relativity
• Special relativity

Images for kids

Transversal time dilation . The blue dots represent a pulse of light. Each pair of dots with light "bouncing" between them is a clock. For each group of clocks, the other group appears to be ticking more slowly, because the moving clock's light pulse has to travel a larger distance than the stationary clock's light pulse. That is so, even though the clocks are identical and their relative motion is perfectly reciprocal.

Statue of Rip Van Winkle in Irvington, New York

• This page was last modified on 16 October 2023, at 16:53. Suggest an edit .

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Time Travel Word Search Puzzle Worksheet Activity

Subject: English

Age range: 8 - 14

Resource type: Game/puzzle/quiz

Last updated

9 July 2023

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A fun and engaging word search puzzle about Time Travel . It’s filled with lots of vocabulary words, and even has an answer key. Plus, it’s super convenient for teachers because it’s a printable PDF worksheet that requires no prep work. You can use it for early finishers, as homework, or as a helpful activity for special education students.

What’s included in this resource? Puzzle (PDF) Answer Key (PDF)

Vocabulary Words Included: Synchrony, Aging, Continuum, Past, Paradox, Leap, Timeline, Retrograde, Transcend, Quantum, Jetlag, Eternity, Vortex, Displacement, Space, Temporal, Tardis, Wormhole, Adventure, Anomaly, Infinity, Loop, Travel, Chrononauts, Chronicle, Wanderlust, Alternate, Momentum

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Grammar Review Digital Escape Room - Escape the Decades - Digital Resources

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Also included in.

Description

Who says grammar review has to be boring? Bring on the fun with this escape room that has engaging challenges including grammar, spelling, and mechanics activities as well as tasks to encourage critical thinking, problem solving, and following directions.

Your students will love this all-digital escape room adventure, where they find themselves in a time warp and need to solve puzzles and complete activities to move through the decades and return to modern times. This would be perfect for decades week or decades day during spirit week! ️

• See information below about tech requirements

⭐️ How does it work? As your students travel through the decades, they will get a taste of the music, fashion, and trends of the different eras all while working through grammar and language challenges. Here are the fun activities they will have for each decade:

• 1950s: choose some songs on a jukebox and go to a sock hop
• 1960s: check out some music posters and buy a van to go to a music festival
• 1970s: go to a disco and shop for leisure suits and 8-tracks
• 1980s: make a mix tape and put together a neon outfit
• 1990s: get familiar with some pop culture icons

Click the Preview link above for a closer look at this activity!

⭐️ The grammar and language challenges involve 2 related topics for each decade, which you may need to review with your students first:

1950s = Spelling

• homophones/commonly confused words
• commonly misspelled words

1960s = Mechanics

• capitalization of titles
• punctuation/quotations

1970s = Verb Tenses

• subject-verb agreement
• avoiding inappropriate verb tense shift

1980s = Pronoun use

• subject and object pronouns
• pronoun-antecedent agreement

1990s = no grammar; just a fun cryptogram puzzle for critical thinking skills

• However, you have the ability to customize the game a bit and delete one or more of the activities to best suit students' needs or to adjust for time.

⭐️ What you'll get:

• A PDF file with a link to a Google Form to assign to students to play the game
• Complete and in-depth instructions explaining exactly how to set up and assign the game to your students
• Detailed answer key with the answers to the puzzles and challenges, as well as thorough and clear explanations about how to solve the challenges and determine the code for each lock
• A student notes sheet (more explanation about this below)

NOTE: While most of the game is grammar and language based, there are a few activities that require thinking outside of the box a bit. An incorrect attempt at opening a lock will give them a hint that should get them on the right track. However, there are a couple of challenges where some students may benefit from an additional hint from you.

There is a small amount of setup that you will need to do, so you will need to go through the activity first . Also, it is helpful to to a trial run of the activity yourself so that you can become familiar with the game and be prepared to assist with hints if students get stuck.

I have also included a notes sheet for students, as well as a teacher copy with suggested hints. The notes and recording sheet can be helpful for students if you do not plan on having them do the entire game all in one day. You may prefer to have them do one or two decades per day, for example, so you can have them keep track of the codes they discovered so they can resume the game on another day.

⚠️ IMPORTANT NOTE ⚠️ This activity is completely digital , and students will need to have access to the following: Google Forms and Google Slides. Please confirm that your school allows access to these types of documents when they are from outside your school district. There are also YouTube links, but they are not critical to the game if your school does not allow access to YouTube. They are just short examples of musical styles from the decades.

⭐️ Benefits of Escape Rooms:

Students love them, so they make excellent back to school icebreaker activities or can be used for those times you want to give them a fun break . They are perfect for holiday parties, days leading up to or following a school break, a stress-relieving activity after state testing days, or any time your students just need a break from the routine.

But the best part is the multiple social and educational benefits : team building and bonding, builds critical thinking skills, encourages creative thinking, improves attention to detail, and develops analytical and problem-solving skills. Love escape room games? Check out the whole collection of escape room games !

⭐️⭐️⭐️⭐️⭐️What teachers are saying about this escape room activity:

• "This was so much fun!" Denelle C. (6th Grade)
• "My students loved this resource! We used it as an activity during Decades Week at school." - Jamie W. (6th Grade)
• "Loved how challenging this was for my students -- even at the end of the year!!" - Amanda N. (6th and 7th Grade)
• "My student had a blast time-travelling and review for our state writing tests. Thanks! This is a wonderful resource." - Mary E. (8th Grade)
• "We used this as culminating grammar study activity. The students loved it! They especially liked some of the songs embedded throughout the activity." - Meghan A. (7th Grade)

⭐️ For another fun escape room challenge, check out Word and Logic Puzzles Escape Room or Jewel Heist Digital Grammar Adventure or for the biggest savings, grab the Escape Room Bundle !

⭐️ Bundle up and Save! ⭐️

If you love puzzles and games that get students thinking , grab the Endless Word Puzzles and Games Mega Bundle for a 50% savings!

❤️ You might also like:

• Dictation for Spelling, Punctuation, Capitalization, and Structure
• Brain Breaks, Ice Breakers and Warm-Up Activities
• Context Clues
• Tense Shift Boom Cards
• Possessive Nouns Task Cards

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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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causation: backward | free will: divine foreknowledge and | identity: over time | location and mereology | temporal parts | time | time machines | time travel: and modern physics

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50 Adventure Time Trivia Questions and Answers

Welcome to the wondrous Land of Ooo! If you’re a fan of the magical and imaginative world of Adventure Time Trivia, you’ve stumbled upon the perfect post. We’ve concocted a marvelous assortment of trivia questions to test your knowledge and take you on a nostalgic journey through the realms of your favorite characters, mysterious creatures, and unforgettable adventures. From Finn and Jake’s daring escapades to the secrets of the Candy Kingdom, this trivia has it all! So, grab your friends, it’s adventure time! Are you ready to uncover the mysteries and prove your expertise in Adventure Time trivia? Let’s get started!

If you like TV Trivia like this, check out:

• Cartoon Trivia
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1. Who is the main protagonist of ‘Adventure Time’?

2. what is the name of finn’s stretchy dog friend, 3. who is the ruler of the candy kingdom, 4. which character often says ‘algebraic’, 5. which vampire plays a bass guitar, 6. what does bmo stand for, 7. which ice-powered character often kidnaps princesses, 8. who used to be a human named simon, 9. who is the flame princess’s father, 10. which character is known for his ‘my new prison is shame’ quote, 11. which candy character lost an arm and has a hook instead, 12. who tries to marry tree trunks in the ‘apple wedding’ episode, 13. which character has a soft spot for ‘everything burrito’, 14. what’s the name of marceline’s pet zombie poodle, 15. what item does finn carry that is made from the fur of a manticore, 16. what’s the name of the game console that lives with finn and jake, 17. which character was made from a piece of princess bubblegum, 18. who is known as the ‘king of thieves’, 19. in which realm does lady rainicorn’s parents live, 20. who did jake marry, 21. what creature is gunter actually revealed to be, 22. who is the guardian of the multiverse, 23. which character can’t see red, 24. in ‘card wars’, what creature is considered overpowered, 25. what is flame princess’s real name, 26. which character turns everything he touches to gold, 27. who is the three-part deity of the adventure time universe, 28. which character became jake’s tail, 29. who did princess bubblegum create to be a suitor, 30. what is the title of the ‘adventure time’ miniseries about marceline, 31. what’s the name of the elephant that makes the best apple pies, 32. which realm is finn originally from, 33. which ‘adventure time’ episode was based on a gender-swapped universe, 34. what type of creature is cinnamon bun, 35. which character used to date a sentient watermelon, 36. which bear imitates everything finn does, 37. who became the king of ooo after princess bubblegum, 38. what color is bmo, 39. who gave finn his grass sword, 40. which character has a catchphrase of ‘unacceptable’, 41. what magical item can translate any language, 42. what’s the name of jake’s children’s mother, 43. who protects wildberry princess from harm, 44. which instrument does jake play, 45. who rules the nightosphere, 46. which wizard sells discounted wishes, 47. who is the banana guards’ leader, 48. what’s the real name of ice king’s crown, 49. who tried to steal jake’s sandwich in the ‘time sandwich’ episode, 50. what’s the name of the deer with hands for hooves.

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Complexity:

1-100+ players

MRE Quest: Golden Key Time Travel Agency. 

Hunt for clues, solve puzzles and explore The Village in Big Bear Lake in this scavenger hunt quest with a puzzle-solving twist. 

Golden Key Time Travel Agency is days away from offering our time travel adventure services to the public, but something went wrong, and now we need to figure out what happened to our travelers that are stuck in time! 

MRE Quest games take you on a trip through Big Bear Lake Village to find clues, puzzles, and riddles during a 1.5-3 hour game . 

Be prepared to walk up to 2 miles throughout the Village and the surrounding area in this Quest! 

This game is conducted completely outdoors (COVID-19 Compliant). Check-in at Mountain Room Escapes in The Village, get your guidebook, and take off on your adventure! When you reach your final puzzle, you will end up back at Mountain Room Escapes to complete your game. 

You will be provided with a guidebook containing a map with 11 separate locations with puzzles, an answer sheet, a phone number to call to ask your game master for questions or hints, and a background story.

Be prepared! Make sure to bring:

• A Hat (to protect yourself from the sun)
• Water (to stay hydrated)
• Good walking shoes 
• A Quarter (you may want to bring one quarter for each player in your group so no one gets jealous… but you only need one for the puzzle 🙂 )
• Detective minds!

This quest is playable for any size group, from 2-100+ players . If your group is larger than 5, you will be given the opportunity to split your group into separate teams so you can compete against each other. 

You will not be “teamed up” with players from outside your booking party, all games are “private”