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00:00 If you were a time traveler, where would you go first of all?
00:04 Forwards or backwards?
00:06 To somewhere within your own lifetime?
00:08 Or to somewhere from within someone else's?
00:11 The possibilities are seemingly endless, but at the heart of it all, there's a problem.
00:17 Because if time travel is to ever exist, then surely it already does.
00:24 This is Unveiled, and today we're answering the extraordinary question; what if time travel
00:31 already exists?
00:34 Do you need the big questions answered?
00:36 Are you constantly curious?
00:39 Then why not subscribe to Unveiled for more clips like this one?
00:43 And ring the bell for more thought-provoking content!
00:50 Back in 2009, Stephen Hawking threw a party for time travelers, complete with a buffet,
00:55 balloons and chilled champagne.
00:57 He waited for his guests to arrive, but ultimately no one came.
01:01 After all, he'd sent out the invitations only after he had thrown the party.
01:05 Hawking saw this as proof that time travel didn't exist, but couldn't deny throughout
01:09 his career that it may be possible.
01:19 Time travel is one of the most popular modern sci-fi tropes around, present in series ranging
01:24 from Harry Potter to Doctor Who, Star Trek and more.
01:27 However, the concept of "travelling in time via mechanical means" was first popularized
01:32 more than a century ago, in 1895, by H.G. Wells' novel "The Time Machine".
01:38 Though it may seem like it belongs only in fiction, however, time travel is scientifically
01:42 plausible and, in fact, technically does already exist.
01:46 That's because Einstein's theory of special relativity explains that time is subjective
01:51 and can speed up or slow down depending on how fast you're going.
01:54 So, if you travel near the speed of light for five years in your time, decades could
01:58 have passed back on Earth.
02:00 Everyone you knew before your trip will have grown old, even though from your perspective
02:04 only a few years will have passed.
02:06 So, today's question, on the face of it, is very plausible.
02:10 Time travel - to the future, at least - is an idea with sound science to back it up.
02:14 In fact, some astronauts have already time-travelled into the future, but only by the smallest
02:19 of margins.
02:20 Russian cosmonaut Gennady Padalka can reasonably claim to be the world's most prolific time
02:24 traveller, as he's spent more time in orbit around the Earth than anyone else.
02:29 Because of time dilation, he's time-travelled around .02 seconds into the future during
02:33 his missions, meaning he's aged .02 seconds less than everyone else alive.
02:38 But that's only time travelling forwards.
02:40 What about travelling backwards in time?
02:42 It's a notoriously tricky concept, and there are certain paradoxes that come into play
02:46 - including "bootstrap theory", which says that bringing an object back in time
02:51 means that the object existed before it was created, and so has no determinable origin
02:56 - a clear problem.
02:57 Then there's the "grandfather paradox", which posits that if someone were to go back
03:01 and kill their grandfather, they would prevent themselves from ever being born, and so would
03:06 never have been able to go back in time in the first place - another sizable issue.
03:10 However, both of these can be solved if we assume infinite timelines and universes, allowing
03:15 for all of the possibilities to unfold.
03:17 So, if time travel exists, it's almost certain that there are countless timelines to cater
03:21 for it, with new realities forming every few seconds.
03:25 In which case, would we ever know that time travel exists, even if it already does?
03:29 There's a chance we might not.
03:31 If technology is developed that allows us to travel around the speed of light, to push
03:35 us into the future, it'd have zero effect on us in the here and now.
03:39 So, as we live our everyday lives driving to work, eating lunch and watching TV, there's
03:44 a seemingly distant (though still very real) possibility that someone else is jetting off
03:48 in front of you, ageing far less rapidly than you are.
03:52 That person could theoretically travel to the year 2100 having only aged a year or two,
03:57 but we'd never know about them because we'd likely never meet them.
04:00 And if we did meet them, we'd perhaps be sceptical of their story.
04:04 But still, via those potentially infinite universes and timelines, we could all be experiencing
04:09 the effects of time travellers messing up our own timelines every day.
04:13 Say someone travelled back in time to prevent you from getting in a car accident.
04:16 They'd then split your life into two; one where you crash in a fatal accident, and another
04:21 where you don't.
04:22 Every time someone spliced your original timeline, they'd birth new ones right alongside it.
04:27 And the multiverse becomes an ever-thickening web of everything that ever was, is or could
04:31 be.
04:32 But you, as in the original you living in your original timeline, would be completely
04:37 oblivious and would never know that time travel existed or that it had shaped your life to
04:41 this point.
04:43 On the other hand, if you were living across one of the other timelines, you might come
04:46 face-to-face with solid proof of time travel.
04:49 So, somewhere out there, a different you could even be time travelling right now, completely
04:53 aware that you exist even if you're unaware that they do.
04:57 If technology for travelling to the past has already been invented (after all, if it's
05:01 to ever exist, then why not right now?), it's likely that world governments would keep it
05:05 under strict lock and key, as that sort of tech could cause huge problems.
05:10 Unless time travel was rigorously regulated, anyone and everyone could show up in all sorts
05:15 of time periods, leaving artifacts from the future, blowing their own cover and altering
05:19 human history.
05:21 Changing even the smallest thing could send ripples through time, all the way up to the
05:24 moment you yourself first time travelled - which could be disastrous for the world around you.
05:29 So, if time travel already exists, then there's surely a time police, too.
05:34 Wouldn't it be their job to stop others from creating chaos?
05:37 Like a time travel version of the Men in Black?
05:39 Maybe even erasing your memory if you'd ever seen anything you weren't supposed
05:43 to?
05:44 More specifically, if time travel really was real, it could provide answers to some unexplained
05:48 phenomena in our standard, non-time travel lives.
05:51 It could be that déjà vu is simply the experience of having our own timeline split by an unknown
05:56 time traveller's actions, leaving us to feel as though we've experienced the same
06:00 thing twice.
06:01 The Mandela Effect, causing shared but incorrect memories, might be another sign.
06:06 Common examples range from believing that Curious George has a tail (he doesn't) to
06:10 recalling that Nelson Mandela passed away in prison (he didn't).
06:14 If time travel already exists, these false memories could be down to some kind of glitch
06:18 caused by inerrant travellers' antics.
06:20 There's no doubt, though, that if time travel does exist, those who know about it and can
06:24 use it have unrivaled power.
06:26 They'd have prior access to news stories, exam questions and lottery numbers (unless
06:30 the time police outlawed it) and, for as long as they could even glimpse the future, they'd
06:35 know which companies were best to invest in.
06:37 More than money, though, they'd have the ability to peek through anybody's life story
06:41 at any time, and potentially the power to reshape, redirect, prolong or cut short any
06:46 life they felt like.
06:48 Without even knowing it, those not privy to time travel would be completely under the
06:52 time traveller's control.
06:54 And the scary part?
06:55 If you accept that time travel's even theoretically possible, then all of that should inevitably
06:59 be happening right now.
07:01 Because, if time travel is to ever exist, then surely it already does?
07:05 Someone, somewhere, at some time should've already mastered it.
07:13 Do you believe that time travel is possible?
07:15 It's one of the most hotly debated concepts in all of science, as well as one of the most
07:20 wished-for hypothetical technologies on the planet.
07:23 Given the chance, would you go forward or back in time?
07:26 It's another deep-rooted question that has us all deeply divided.
07:30 So, whenever there's even a sniff of a real-life time travel story, it usually attracts a lot
07:35 of attention.
07:36 And in this video, we're going to look at four of the most compelling temporal tales
07:40 from four different corners of the world map.
07:51 First and arguably the most famous time travel story of modern times, John Titor.
07:56 An alleged American soldier sent back from the year 2036, he posted on a spate of internet
08:02 forums in the early 2000s, originally under the name of "Time Travel Underscore Zero".
08:07 At the time, Titor's messages caused a stir because they appeared to place him across
08:12 three separate generations.
08:14 According to him, he was first sent back to the year 1975 to regain an early IBM 5100
08:21 computer.
08:22 The retro machine was apparently needed to prevent computing problems in the future,
08:26 a reference that some of Titor's audience took as relating to the year 2038 problem.
08:32 A predicted Y2K-style computer glitch scheduled to happen two years after Titor's original
08:37 time.
08:38 The seeming time traveller explained his appearance at the turn of the century, though, as him
08:42 simply "stopping off" on his way home.
08:45 In his posts, Titor made various references to imminent civil war in America between the
08:50 years 2004 and 2015, and even to the outbreak of World War Three shortly afterwards.
08:56 Today, we know that that didn't happen.
08:59 But believers claim there's a ready-made explanation at hand.
09:03 Crucially, Titor also advocated the "many worlds" theory of reality as being the correct
09:08 one.
09:09 It was something which he suggested was common knowledge by 2036.
09:12 And it's an important part of the story because it effectively means that any predictions
09:16 Titor made that didn't come true could be explained away by it.
09:20 So, the theory goes that his reappearance in 2000 could have caused a split in the timeline
09:26 and, fortunately for us, that split meant that war in this world was avoided.
09:30 So, what do you think?
09:32 Did John Titor save the world?
09:34 Or was it all just an elaborate hoax?
09:37 For our second, and perhaps even stranger, time travel claim, we're headed across the
09:41 Atlantic to Europe and France.
09:43 What's come to be known as the "Mowberley-Jordain Incident" also took place almost exactly
09:48 100 years before John Titor took to his keyboard.
09:51 And, it does what all good time travel stories should do, by adding ghosts into the fray
09:56 as well.
09:57 In 1901, Charlotte Anne Mowberley and Eleanor Jordain were two academics visiting Paris
10:03 shortly before they began working together at Oxford University.
10:06 As part of their trip, they took in the Palace of Versailles, where, while exploring the
10:11 gardens, they took a wrong turn and became lost.
10:14 And right about now was when it got… weird.
10:17 Both remembered walking along the outskirts of a wood when they alleged that the world
10:21 around them subtly changed.
10:23 The trees reportedly took on an unreal quality, and they came across a variety of unusual
10:28 characters dressed in old-fashioned clothing.
10:31 One in particular caught the attention of Mowberley; a woman in traditional dress stood
10:35 on an open lawn, apparently "sketching the landscape".
10:39 Eventually, Mowberley and Jordain found their way back to the palace, and a week later,
10:43 traded notes on what they both suspected had been a paranormal experience.
10:48 The main idea was that wherever they had stumbled upon had been haunted, but also that in being
10:53 there, they had travelled back in time.
10:55 They would spend the next ten years gathering more research before publishing, under pseudonyms,
11:00 on account of their experience in the 1911 book, "An Adventure".
11:04 Among the most noteworthy claims they made in it were that they believed that they had
11:08 travelled back to the late 1700s, and also that the sketching woman had been Marie Antoinette.
11:15 In the time since, the Mowberley-Jordain incident has been explained away by others as a number
11:19 of things, including a shared delusion and an unknowing encounter with a period costume
11:25 party.
11:26 But what's your verdict?
11:27 Could there really be some kind of portal in the Palace of Versailles grounds?
11:30 Or were these Oxford academics simply mistaken?
11:33 From Paris to Rome, and more specifically, the Vatican City, where there are some serious
11:37 claims that the church has a secret and ongoing history of dabbling with time travel, too.
11:43 The chronovisor is probably one of the craziest machines ever said to have existed anywhere,
11:48 any time.
11:49 According to those who claim it to be real, it's a bizarre, cabinet-like contraption,
11:54 packed with buttons, gadgets and gizmos, all designed to totally reconstruct our experience
11:59 of time.
12:00 A chronovisor user is said to be able to view any past event through the machine, thanks
12:05 to some spectacular technology that can somehow convert electromagnetic radiation into effective,
12:11 backwards time travel.
12:12 Or, at least, convert it into a window through which you can revisit actual history.
12:18 Claims mostly come from a one Fr.
12:20 François Brune, a Catholic priest who wrote about the chronovisor in his 2002 book, "The
12:25 New Mystery of the Vatican".
12:27 Broadly speaking, Brune claims that the device was built by another priest named Pellegrino
12:32 Ernetti, and allegedly with the help of many of the world's leading scientists in the 20th
12:37 century, including Enrico Fermi, today famed for the Fermi Paradox.
12:42 Fr.
12:43 Ernetti is then said to have used the chronovisor to go back in time to observe the actual crucifixion
12:47 of Jesus Christ.
12:49 And while Ernetti's claims have been continually challenged, and even he himself reportedly
12:53 admitted making them up, proponents to the chronovisor's existence insist that it's
12:59 real.
13:00 And, now that after Ernetti was allegedly forced into casting doubt over it, the machine
13:04 is today used in secret by a global elite to control world governments.
13:08 Of course, if it does exist, then it's something unlike anything else ever built on Earth.
13:13 Would it surprise you if there were a machine like this, used by a select few to pull the
13:17 strings of society?
13:19 Our last time travel story is perhaps a little more grounded, but strange all the same.
13:24 And this time, we're headed for the UK.
13:26 The city of Liverpool is famous for many things; the Cavern Club, the Beatles, Anfield… but
13:33 did you know there's also a real-life time warp there?
13:36 Allegedly.
13:37 Most of the reported stories centre around Bold Street, an area full of shops and shoppers.
13:43 And while most of the time you can stroll around this part of town and stay firmly in
13:47 the here and now, there have been some occasions when people have reported suddenly being transported
13:52 back to a bygone era.
13:54 The most famous case involves a former policeman who was out shopping in the year 1996.
14:00 His wife went to a nearby bookstore while he went to pass time elsewhere.
14:04 But then, when he went back to meet up with his wife again, he was confused to find that
14:08 the bookstore wasn't there.
14:10 In its place was a clothes shop, and it didn't turn back into a bookstore until he stepped
14:14 through the door.
14:15 Thankfully, husband and wife were swiftly reunited, and nobody was lost in time forever.
14:21 But when the former policeman came to realise that the same building had been a clothes
14:24 shop decades beforehand in the 1960s, that's when this particular tale took on a whole
14:30 new meaning.
14:31 It was as though he had been briefly transported back in time and given a glimpse of history,
14:36 in a similar way to how Charlotte Anne Moberly and Eleanor Jordain felt after their experience
14:41 in Paris.
14:42 Both Liverpool and Paris are fine European cities, granted… but could they also have
14:47 something truly incredible in common with one another?
14:50 If these stories are to be believed, then they both offer the unsuspecting visitor the
14:54 possibility that they might suddenly be plunged back into the past.
14:58 Failing that, you could always visit the Vatican to try to unearth the chronovisor and at least
15:03 be given the opportunity to observe times gone by.
15:06 Or else you can keep regular tabs on the internet's time travel forums, in the hope that one John
15:11 Titor might make another appearance soon.
15:17 For generations, we've pondered what it would be like to meet aliens.
15:21 What would happen if an extraterrestrial visitor arrived on Earth tomorrow?
15:25 Would we greet it, fight it, or run away in terror from it?
15:28 Well, according to some theories, there might not actually be that many differences between
15:33 us and them.
15:34 One of the biggest questions that believers in UFOs and extraterrestrial visitations have
15:49 to answer is why?
15:50 Why would aliens go to so much trouble to travel so far across the universe to come
15:54 and abduct just a handful of random Earthlings?
15:57 Is Earth special to them?
15:59 Have we been targeted?
16:00 Or is every alleged alien encounter in history simply the result of random chance?
16:05 These problems, though, are eliminated if we consider for a second that flying saucers
16:09 aren't far-off spacecraft but that they're time machines instead - filled not with otherworldly
16:15 creatures but with humans from the future who we might reasonably assume would know
16:19 that the Earth is here.
16:21 This isn't yet a widely accepted theory, and there are many other, far more mainstream
16:25 predictions on what alien life will or could look like… but there are growing numbers
16:29 of scientists and professors lending their thoughts to it, too… most notably one Michael
16:34 Masters, a professor who published a book in 2020 on what he calls a "multidisciplinary
16:40 scientific approach" to UFOs.
16:42 In it, he discusses the possibility of future humans returning to the here and now… and
16:47 being mistaken for aliens.
16:49 And regardless of where you stand, it does make for an interesting thought experiment.
16:54 Because if you were given a working time machine, wouldn't you want to go, yes, to the future
16:58 to see what becomes of humanity, but also to the ancient past - to see some of your
17:02 favourite historical periods up close?
17:05 And when you arrived in the ancient past, wouldn't you imagine that you might be greeted
17:08 with wonder, suspicion or fear?
17:11 All of the same emotions you might expect to exhibit upon meeting an alien.
17:15 If we, in the present then, would love a time machine to visit the past, the same would
17:19 probably be true of humans in the future… only, for them, our present is their past.
17:25 Time travel is arguably the most talked-about sci-fi concept of all, with all manner of
17:29 high-profile figures making predictions about whether it will or will never exist.
17:34 But if backwards time travel specifically is to exist at any time in the future, then
17:38 we're just as likely to encounter it now as at any other time in history.
17:42 All it would take would be a future time traveller keying in to a specific date, and there you
17:47 go!
17:48 If they were spotted, some would call "UFO"; and if they were spoken to, some would call
17:52 "alien".
17:53 From the time traveller's point of view, going to the ancient world would be, in some
17:57 ways, just as foreign or alien as going to a different planet.
18:00 They'd be faced with a completely different society and way of life; long-forgotten customs,
18:05 languages, foods and technologies… but the basics, the building blocks of life and survival,
18:11 would be pretty much the same.
18:12 If you were travelling backwards from the present day, for example, you wouldn't need
18:16 to undertake rigorous studies just to test whether the air in ancient Egypt is safe to
18:20 breathe.
18:21 You'd just need to remember to pack enough water, and maybe some sunscreen.
18:24 In this way, in the hypothetical future when both exist, time travel technology could actually
18:29 be the safer option compared to interstellar space travel.
18:33 But why would these travellers want to visit the twenty-first century, specifically?
18:37 In recent years, we have seen a general increase in the number of UFO sightings reported.
18:42 And there are a number of explanations for this, but in the context of today's question,
18:46 would there be anything in particular pulling time travellers to this specific time period?
18:51 Knowing that future humans, from a time where backwards time travel exists, will also most
18:55 likely have moved away from Earth, across the solar system and perhaps further, it could
18:59 still be as simple to them as just wanting to know where they came from.
19:03 This interstellar immigration could be a search for cosmological roots that leads them all
19:08 the way back to present-day Earth.
19:10 These humans could have been raised on a newly terraformed Mars, or in the clouds of Venus
19:14 above the oceans of Europa and Titan, or on centuries-old generation ships just drifting
19:19 through the void.
19:20 If you were them, wouldn't you want to see the planet where humans originally lived?
19:25 This effectively means that all those UFO sightings we so often hear about on the news
19:29 or on the internet would actually now be tourists.
19:32 Time tourists.
19:33 It's still not likely we'd take them at their word, though.
19:36 Until we actually develop time travel technology for ourselves, if that's even possible,
19:41 then the majority of people would be at least hesitant to believe anyone claiming to have
19:45 genuinely come from the future.
19:46 But it's also true that often the aliens that people allege they've seen aren't
19:51 actually that alien in description.
19:53 The stereotypical extraterrestrial in sci-fi and most abduction claims is really quite
19:57 humanoid.
19:58 They may have grey or green skin, they might be a little shorter, and they often have larger
20:03 heads and eyes, but they're still fairly close to us with four limbs and recognisable
20:07 features.
20:08 And this human-like appearance ties into today's question, with the suggestion being that if
20:12 these strange creatures are actually just highly evolved humans from the future, that's
20:16 why they look a bit like us.
20:18 If we assume that future humans will have gone to live on different planets, they could
20:22 have also begun to evolve at unprecedented speeds and in unprecedented ways, simply to
20:27 adapt to and survive wherever their new home was - meaning larger eyes, bigger heads, and
20:32 longer fingers, for any number of reasons.
20:35 Of course, what's more generally accepted as the likeliest explanation is that alien
20:39 abduction claims feature these physical tropes because science fiction has steadily perpetuated
20:44 this particular aesthetic.
20:45 Still, for as long as we don't have any concrete proof that life exists on other planets
20:50 - which we still don't - and for as long as we know that humans on Earth are interested
20:54 in developing working time travel - which we still are - the idea that the two could
20:58 marry up can't quite be totally dismissed.
21:01 So, let's imagine for a moment that we live in a future time when this far-fetched theory
21:06 is a real-world reality, and it's been uncovered that UFOs really are time machines.
21:11 Should we be worried?
21:12 Well, countless studies and thought experiments have shown that travelling back in time could
21:16 have terrible consequences.
21:19 Anyone doing it could breach a variety of paradoxes, and prevent important events from
21:23 happening, accidentally cause horrible things to happen, or even stop themselves from being
21:28 born.
21:29 But, perhaps, herein lies another reason to believe that UFOs are time travellers?
21:33 If the dicey history of UFO reports proves one thing, it's that these vehicles rarely
21:38 hang around for long enough to be proved or disproved themselves.
21:41 But, in a world where they're actually piloted by time travellers, maybe this is just an
21:46 exercise in damage limitation?
21:48 The high risk involved with time travel could mean that, if we ever did invent it, it would
21:52 probably be strictly regulated.
21:55 Anyone travelling back in time would be under strict command not to alter anything about
21:59 the past and not to be seen.
22:01 For the most part, then, it works fine… but every so often a present-day human encounters
22:05 flashing lights or stumbles across a levitating disc and the cover is blown.
22:10 That is, unless the travellers can disappear quickly enough or make their appearance incredible
22:14 enough so that it'll never be believed.
22:17 It offers one explanation as to why so many alien abduction claims include instances of
22:22 missing time or memory problems.
22:24 That part is a traveller's last-ditch attempt to fix their mistake.
22:28 If you accept a deterministic model of the universe - one in which everything will always
22:32 inevitably happen however it's supposed to - then, really, none of this should be
22:36 of any concern to you.
22:37 If UFOs are piloted by extraterrestrials or time travellers, or if they're a total myth,
22:42 it makes no difference.
22:43 And, as for all of the dangers that time-travelling UFO pilots could bring with them, well, they're
22:48 not dangerous at all.
22:49 Because whatever changes they do or don't make, always were or weren't meant to be
22:54 made.
22:55 However, if you're more inclined to free will, you don't not believe in UFOs, and
22:59 you have even a sneaking suspicion that one day, time travel might be possible… then
23:03 today's question is one meeting place for all of those things.
23:07 We repeat, it's not yet a widely accepted theory, but it is an eye-catching thought
23:12 experiment.
23:16 Everything has to end eventually.
23:18 Our days, when the Earth completes one rotation; our years, as it makes its way through all
23:22 of the seasons; and the decades pass one after another, after another.
23:26 Humans, just like all living creatures, have a limited lifespan.
23:30 One day, they'll die, and so will everything else out there.
23:33 The Earth, the sun, the whole galaxy… but what about reality itself?
23:47 Practically every belief system has its own depiction of an "end time", a prophesied
23:51 apocalyptic scenario that it's believed will one day happen.
23:54 It may involve the second coming of a figure like Jesus Christ, a battle with the forces
23:58 of evil, or just a general spate of large-scale, across-the-board ruin and destruction known
24:03 as Judgment Day.
24:05 Even with the likes of Buddhism, where rebirth cycles are incredibly important, there are
24:09 writings about "end times", where the Buddha is forgotten and society collapses.
24:13 There have also been plenty of secular theories about something destroying the world.
24:17 The Millennium Bug, for example, triggered frantic concerns over computers struggling
24:21 to cope with the year change from 1999 to 2000… with some fearing a massive, world-wrecking
24:26 glitch causing a fairly literal "end of time".
24:29 Elsewhere, we've seen various other prophecies come and go, including the 2012 apocalypse
24:34 theories based on the Mayan calendar which billed December 21st of that year as "the
24:39 doomsday moment".
24:40 It again received plenty of attention, but again didn't translate into actual annihilation.
24:45 But regardless of the apocalypses that so far haven't happened, for many it's inevitable
24:49 that time will one day end.
24:51 And since time and space are inextricably linked, this future point of incredible destruction
24:56 can also be generally understood as the "end of the universe".
25:00 There are other ways to interpret the question, like the death of time equating to the death
25:04 of the sun, if you take time to mean humanity's method of measuring it.
25:08 Or perhaps the "end of time" actually passes when Earth itself expires, or when
25:12 there are no humans left to perceive time in the way that we do.
25:16 And as with most conundrums surrounding time, there's also the question of black holes
25:20 and the massive, maybe infinite, distortions you yourself would experience were you to
25:24 somehow fall into one.
25:26 But in terms of a total blackout, the final destination for anything and everything, the
25:30 end of the universe, is the only scenario where it might also be said that time truly
25:34 stops moving.
25:35 So, to see the end of time, you'd have to also be present at the end of space; a practical
25:40 impossibility but a theoretical prospect.
25:43 We know that time travel into the future is theoretically much simpler than time travel
25:47 into the past.
25:48 And there are also various far-future theories on how we might one day achieve immortality,
25:52 which offer another route to front-row seats at the end of all things.
25:56 With the time travel option, the theoretical problems with travelling back into the past
26:00 would unfortunately mean you'd never be able to tell anybody that wasn't already
26:03 there that you'd seen the end of time.
26:06 And with the immortality approach, you'd have essentially discovered that even everlasting
26:09 life has its limits… but you'd at least be present to see the ultimate endgame.
26:14 In either case, knowing precisely when the end of time will happen is key.
26:17 Estimates vary wildly, with some theories suggesting that the universe only has a few
26:21 billion years left to run, while others say that if reality does ever end, it won't
26:26 happen for hundreds of billions, perhaps even trillions of years.
26:29 The window we've got to work in, then, is exceptionally wide.
26:33 But exactly what you'd see when you eventually got to the correct time and place depends
26:37 on which of the various "end of the universe" theories proves to be the right one.
26:41 Over the years, a lot of predictions have been authored up.
26:44 Heat death, or the "Big Freeze", is a reasonably well-supported idea; where the
26:48 universe reaches thermodynamic equilibrium and can no longer increase entropy.
26:53 In other words, it gets too cold to function when, in the far, far future, all of the black
26:57 holes in existence close up, no longer able to even sustain themselves.
27:01 But there's also the "Big Crunch" theory, a now less popular idea in modern science,
27:06 but one where it turns out the expansion of the universe we are currently in the middle
27:09 of isn't endless, and that it will one day revert inwards and back towards an eventual
27:13 collapse.
27:14 If neither of those come to pass, there's also the "Big Rift" theory, which some
27:18 predict could happen after an increase in the amount of dark energy present in the universe.
27:23 Right now, we think the universe is about 68% dark energy, but say it climbed closer
27:28 to 100%, it could ultimately tear itself apart, condemning everything inside the universe
27:33 to another inescapable doom.
27:35 Finally, the "Big Bounce" is a best-of-all-worlds scenario and arguably the least destructive
27:40 option; where the universe endlessly expands and contracts forever, as though it's breathing.
27:45 In some ways, there actually wouldn't be an "end of time" in this case, but there
27:48 would be various stages in a now-eternal cycle where next to nothing exists.
27:53 However, it plays out, if you somehow travel to the end of time and survive to witness
27:57 it, you'd be left with… darkness.
28:00 Blank, literal, total nothingness everywhere.
28:03 A bottomless void in the truest sense, where even your own existence would actually be
28:07 impossible.
28:09 With time and space no more, you yourself couldn't age, grow or even function.
28:13 As will have happened with everything else, from planets to stars to even supermassive
28:17 black holes, the matter that makes up your body would now be impossible, too.
28:22 Even in some kind of indescribably futuristic, seemingly indestructible spaceship, you'd
28:26 be a goner as soon as you arrived at your "end of all things" destination.
28:30 If time really does end and you really could jump forward to see it, then you'd simply
28:34 be fast-tracking your own demise.
28:37 But perhaps there's a silver lining to arriving at your own inevitable departure.
28:41 Seeing as energy can't be created or destroyed, the residue of the universe - the remnant
28:46 of space-time - has to go somewhere, particularly if you subscribe to the Big Crunch or Bounce
28:51 theories… and you would've been there at the very close.
28:53 So, perhaps no sooner would you be gone before you'd reappear, at the birthing of a new
28:58 universe or the beginning of a "new time".
29:01 Regardless of whether you lived, died, were ruthlessly annihilated in the blink of an
29:04 eye or wondrously reborn into a brand-new reality, however, you'd have played your
29:09 part in the absolute rarest event in cosmology; a moment to defy description or even comprehension.
29:15 What's your verdict on time travel?
29:18 Let us know in the comments and tell us exactly where you'd travel to, if you had the chance!
29:23 Perhaps there are already time machines out there.
29:27 Perhaps all those time travel stories really are true to life.
29:30 Maybe time travel has evolved so far that it's become an alien superpower.
29:36 And maybe, one day, it will take us to the end of time too.
29:41 Because that's what would happen if time travel already exists.
30:11 What do you think?
30:12 Is there anything we missed?
30:14 Let us know in the comments.
30:15 Check out these other clips from Unveiled, and make sure you subscribe and ring the bell
30:20 for our latest content.
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