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00:00 Is there anything more mysterious, intriguing, or unknown than a black hole?
00:05 Answers in the comments!
00:07 But for now, it's clear that when it comes to space and the cosmos, black holes are a
00:11 never-ending well of wonder, a bottomless pit of potential.
00:16 But they're also one of the trickiest things to wrestle with in all of science.
00:20 Over the years, there have been countless theories put forward as to their true nature,
00:25 and in recent times we have begun to get a better grip on them.
00:28 But still, there are some ideas about black holes that, if they were ever proven to be
00:32 right, would change our understanding of everything, forever.
00:37 This is Unveiled, and today we're taking a closer look at a bizarre theory that black
00:41 holes could double up as portals.
00:45 Do you need the big questions answered?
00:47 Are you constantly curious?
00:48 Then why not subscribe to Unveiled for more clips like this one?
00:51 And ring the bell for more thought-provoking content!
00:54 It's often said that you can find yourself "down the rabbit hole" whenever you spend
00:58 time researching big hypotheticals and alternate theories.
01:02 Sometimes it's pretty fun down there, and sometimes it's a little bit frightening.
01:06 But really, it's black holes that represent the ultimate rabbit hole in actual physical
01:10 existence.
01:11 These are truly massive openings in space itself, and it's a one-way ticket for anything
01:16 that enters them.
01:18 If you were to fall down the rabbit hole of a black hole, then you ain't coming back!
01:22 These enigmatic cosmic objects are often characterised as ruthless monsters that devour everything
01:27 in their vicinity.
01:28 Nevertheless, they've long captured the imagination of scientists and space enthusiasts
01:34 alike.
01:35 In general, black holes are formed from the remnants of massive stars breaking under their
01:39 own gravity.
01:40 When massive enough stellar cores exhaust their nuclear fuel, they undergo a collapse
01:45 so dramatic that the gravitational force involved becomes so intense that it warps spacetime.
01:51 Eventually, it's a process that creates a specific region from which nothing can escape.
01:57 In the structure of the resulting black hole, this point of no return is ultimately known
02:01 as the "event horizon".
02:04 Not all black holes are equal, though.
02:06 There are various types, including stellar black holes (which again result from the collapse
02:10 of massive stars), but also supermassive black holes.
02:15 These are usually found at the centres of most galaxies, including at the heart of our
02:19 own Milky Way.
02:20 The formation of supermassive black holes is a little less set in stone, with theories
02:25 ranging from them being produced when a tightly-knit star cluster collapses, or when other, smaller
02:31 black holes merge together.
02:33 Overall, the estimated number of black holes in the observable universe is vast, ranging
02:38 from tens of millions to possibly multiple billions or more, depending on the model and
02:44 method used to calculate.
02:46 Given that there are so many unknowns swirling around these immense celestial structures,
02:50 it's perhaps unsurprising that black holes have become a magnet for outlandish ideas.
02:55 But actually, the one at the top of today's video - the idea that black holes could also
03:00 be portals - isn't really so radical or off the wall.
03:04 For decades, theoretical physicists have suggested that they might also be gateways to other
03:09 dimensions or even parallel universes.
03:12 So, how would such cosmic connections unfold?
03:16 In one sense, the key word is "wormhole".
03:19 Much more than a glittering highway in our favourite science fiction movie, wormholes
03:24 are genuinely hypothetical tunnels in spacetime that could connect two separate points in
03:29 the universe.
03:30 Proposed within the framework of Albert Einstein's general relativity, they're often visualised
03:35 as bridges.
03:37 More directly, the Einstein-Rosen bridge is a specific type of wormhole that also works
03:42 as a shortcut through the fabric of space.
03:45 In general, it's said that that fabric - otherwise known as spacetime - could be manipulated
03:50 so that two points even light-years away could be brought together.
03:54 It's often demonstrated by marking two points on a piece of paper, folding that paper in
03:59 half so that the points match, and piercing a pencil through both.
04:04 In a pretty primitive sense, that's a wormhole.
04:07 And that's what some have said could be happening inside a black hole.
04:10 We of course know that any matter that falls into a black hole is apparently lost forever.
04:15 Given that black holes themselves will eventually disappear as well, this is a problem, known
04:19 as the information paradox.
04:22 That has long puzzled researchers because quantum mechanics says that nothing can be
04:26 totally lost.
04:27 However, if black holes were portals, then the information paradox is solved, because
04:32 any and all matter and information that falls into one is then set to re-emerge out of it
04:37 somewhere else.
04:38 In some models, this exit at the other side is known as a white hole, but more on that
04:43 shortly.
04:44 But first, there's the holographic principle to consider, as well.
04:47 This again rests on the quantum reality that information of any kind should never be lost.
04:53 Only here, the explanation for what apparently happens in black holes is slightly different.
04:58 The holographic principle proposes that the information inside is somehow encoded on the
05:03 event horizon in a two-dimensional form.
05:06 Some theorists then suggest that, at this stage, the information that was once physical
05:10 matter could be transferred to, or at least imprinted onto, another plane.
05:15 So, here, again, a black hole would work something like a portal.
05:20 Perhaps not in the more traditional wormhole sense, but it would still represent a checkpoint
05:24 between here and there.
05:26 Wherever "there" is.
05:27 Still, the concept of white holes is key.
05:30 While black holes devour matter, white holes theoretically expel it.
05:35 They are imagined regions of spacetime into which nothing can enter, but out of which
05:39 matter and energy can freely and rapidly exit.
05:43 Whether it's fuelled by the holographic principle, or propped up by a relatively simple
05:47 wormhole, the discovery of a white hole would be the smoking gun moment for all theories
05:53 toward black holes being portals.
05:55 The problem is that, so far, there are no white holes that we know about.
05:59 Nevertheless, many theorists remain confident.
06:03 The reason why has to do with how we answer the related question "where do black holes
06:07 lead?".
06:08 The possibilities are not only as vast as the universe itself, but also as wide and
06:13 unending as the multiverse.
06:16 So much so that it could be that no black hole leads to another point in this universe,
06:21 and that's why we have no white holes to speak of.
06:23 Instead, all black holes funnel their matter into a different universe.
06:28 And black holes themselves are, therefore, the key infrastructure to how the multiverse
06:33 works.
06:34 It could be that they foster connections between us and parallel universes with entirely different
06:39 physical laws, or alternate planes made up of multiple extra dimensions beyond our own.
06:45 Such a radical rethinking of how the universe works more than stretches the boundaries of
06:50 our current scientific knowledge.
06:51 It essentially destroys everything we thought we knew.
06:55 For some, it's a possibility that ties all the way back to the beginning of matter itself,
06:59 the Big Bang.
07:01 For decades, the Big Bang theory has been the leading model to explain how the universe
07:05 came to be.
07:06 But discussion of it is always overshadowed by one seemingly crucial problem.
07:11 If everything came from the rapid expansion of one singularity, as the Big Bang says,
07:16 then where did that one singularity come from in its first form?
07:20 How did something come from nothing?
07:22 Well, what if the Big Bang was actually a white hole?
07:25 In fact, what if it still is a white hole in action?
07:29 While highly speculative, increasing numbers have begun to debate the possibility that
07:34 actually, the entire universe is merely the product of the exit point of a black hole
07:39 portal - one that was opened up around 13.8 billion years ago to our minds.
07:45 This exit point - a massive, white hole - can account for literally everything we know about;
07:51 for our physical reality, and for its continued expansion from that point onwards.
07:56 Could it even be that it's an irresistible force of an expelling white hole that's
08:00 powering universal expansion in general?
08:03 Questions like these aren't yet mainstream, but the allure of white holes has gotten plenty
08:08 of people wondering.
08:09 So, what's your verdict?
08:11 What do you think happens on the inside of a black hole?
08:14 Is there any merit to the suggestions that these brilliant behemoths might ultimately
08:19 be cosmic gateways at their heart?
08:21 And if it were possible to travel through one, to reach another side… then is it so
08:26 unlikely that that's all this universe is, as well?
08:30 Another side, from the point of view of somewhere else, across a multiverse that's connected
08:35 by these dazzling bridges?
08:38 Because that's the bizarre theory that black holes could double up as portals.
08:43 Black holes are among the most mysterious objects in the universe, ready and willing
08:47 to devour anything that gets too close to them.
08:50 Luckily, the closest black hole to us is more than a thousand light-years away… but what
08:54 would happen if one showed up actually on this planet?
08:58 This is Unveiled, and today we're answering the extraordinary question; what if a black
09:02 hole appeared on Earth?
09:04 Are you a fiend for facts?
09:06 Are you constantly curious?
09:08 Then why not subscribe to Unveiled for more clips like this one?
09:11 And ring the bell for more fascinating content!
09:14 Because black holes generally form when a star dies and collapses, they themselves are
09:18 extremely massive.
09:20 For an ordinary black hole, you first need a star with a mass at least eight times greater
09:24 than that of our sun… which is why the sun will never become a black hole itself.
09:30 Supermassive black holes naturally demand even more mass, while ultramassive black holes
09:34 have a mass more than ten billion times that of the sun.
09:38 The largest discovered so far was found in 2019, at an incredible size of forty billion
09:43 solar masses.
09:45 If a black hole this size, or anything remotely close to this size, came close to Earth, the
09:49 entire population of the planet would quickly die.
09:53 And not in a pleasant way.
09:54 When you fall into a black hole, the force of gravity acting on your feet is so much
09:58 stronger than the force of gravity acting on your head that you get stretched out.
10:03 Infinitely stretched out.
10:05 Until your entire body is reduced to one long, single string of atoms, which ultimately gets
10:10 crushed down into the singularity like literally everything else.
10:14 This process is called spaghettification, and for a black hole to appear here, it would
10:18 happen to all of us all at once.
10:21 All of us together, plus everything we've ever known, being ruthlessly, inescapably
10:25 pulled apart at the atomic level.
10:27 It's not exactly a happy thought, is it?
10:30 Aside from the destruction, though, black holes are also widely known for distorting
10:34 the time and space around them.
10:36 In reality, if we ever shared a planet with a regular, stellar black hole or bigger, we'd
10:40 be dead far too quickly to notice any kind of strange time dilation or gravitational
10:45 warping that might happen.
10:47 Time dilation, in particular, is only really noticeable if you had an observer both inside
10:51 and outside of the black hole - an impossible feat.
10:54 Say a black hole really did appear here, pulled us all past its event horizon, and we were
10:59 all alive and aware enough to know what was going on… which definitely wouldn't be
11:03 the case… all we'd really see is everyone else experiencing time and space, life and
11:08 death in the exact same way as ourselves.
11:10 To us, the time warp wouldn't exist.
11:13 But what about for an extremely tiny black hole?
11:15 Does such a thing even occur?
11:17 So-called "micro" black holes are still hypothetical, but this doesn't mean they're
11:21 not real, and that they're not a real concern.
11:24 For years now, people have worried that particle accelerators, specifically the Large Hadron
11:29 Collider in Europe, might be able to create black holes.
11:32 And, of course, if they ever did, then this really would constitute a black hole appearing
11:37 on Earth.
11:38 Experiments started at the LHC in 2010, so they're more an ongoing study nowadays - a
11:43 background story for life on Earth - rather than regular headline-making news.
11:47 Still, if anything ever did go wrong, we'd know all about it.
11:51 It's thought that, were a micro black hole to appear on this planet, whether as a result
11:55 of particle accelerator experiments or not, then it would instantly dissipate because
11:59 of its small size.
12:01 Which sounds like a good, non-life-threatening situation, but unfortunately it's also believed
12:06 that the energy released just from that happening would easily dwarf that released from a nuclear
12:10 bomb.
12:11 While this wouldn't necessarily be world-destroying, it would certainly kill everybody in the immediate
12:16 area - potentially millions of people.
12:19 If we had a particle accelerator at the bottom of the sea, rather than beneath the France-Switzerland
12:23 border as per the LHC, perhaps micro black hole creation wouldn't be quite as deadly
12:28 to humans - though it would still devastate marine life and trigger untold tsunamis.
12:33 A slightly larger black hole, but one that's still smaller than a stellar black hole, would
12:37 bring its own set of problems, too.
12:40 Say one with close to the mass of Earth opened up tomorrow - a wholly hypothetical prospect
12:44 because science doesn't yet know of a way that a black hole like this could even happen.
12:48 Well, it would also wreak havoc.
12:50 A black hole of this size would still look very small to the human eye, but it would
12:54 be strong enough to slowly consume our entire planet, piece by piece.
12:59 We might be afforded a little bit of time - time enough, perhaps, to escape to the moon
13:03 or Mars in a far-future world - but, before long, with the planet itself devoured, such
13:08 a black hole could even take Earth's place in the solar system.
13:12 The moon would now orbit around it, potentially without any other major changes.
13:16 Theoretically, though, the opposite could also be possible.
13:19 You can fit all of the other solar system planets end-to-end between the Earth and the
13:23 moon, so our closest satellite is still a long way away.
13:26 If a black hole, then, with the same mass as the moon, took up the same spot as the
13:30 moon, could it also orbit around us?
13:33 For at least a short time, maybe it could… even if it would appear tiny compared to the
13:37 moon, and far too tiny to see from the ground.
13:40 Thanks to modern science and astronomy, we know today that many exoplanets and stars
13:45 orbit black holes perfectly, safely out in the universe.
13:48 We also know that black holes can orbit each other, and that our galaxy has a supermassive
13:52 black hole at its centre - or, according to some theories, two supermassive black holes
13:56 at its centre.
13:57 What's especially crucial to this thought experiment, though, is that scientists have
14:02 also discovered before that a black hole can orbit a star.
14:05 The star just has to be more massive.
14:07 Ultimately, black holes are objects in space, like everything else, and they behave according
14:12 to the mass of what's around them.
14:14 Place a hypothetically moon-sized black hole, in terms of mass, precisely where the moon
14:18 is now, then, and the night sky would look totally different.
14:21 And scientists would have the ultimate opportunity to study these cosmic enigmas at close quarters.
14:26 Today, we have just a single, blurry image of an extremely distant black hole… but
14:31 now we'd have the universe's ultimate destroyers within touching distance.
14:35 The downside?
14:36 Well, having a black hole that close to us could well prove unsettling.
14:40 Every time we looked into, or thought about, the sky, there'd be a reminder of how close
14:44 we are to a quick demise via the dreaded spaghettification.
14:48 But it's perhaps worth noting that Earth is already affected by distant and dangerous
14:52 celestial objects - not least the sun.
14:55 While sunlight is needed for life on Earth, the sun would be just as dangerous as a black
14:59 hole if it were ever to move closer to us.
15:02 In terms of potential for danger, falling into a star isn't any more or less fatal
15:06 than falling into a black hole.
15:08 Both will quickly kill you.
15:10 Yet, we're obviously used to the sun.
15:12 It's been there for all of our lifetimes, and throughout Earth's existence, so we
15:16 rarely imagine that it'll be the end of us.
15:19 Perhaps in an alternate world where a tiny black hole hung in the sky as well, we'd
15:23 grow to feel the same way about it.
15:25 On the planet's surface, even a micro black hole could have devastating consequences,
15:30 potentially killing millions or even the Earth's entire population.
15:33 If the right-sized black hole appeared just in the vicinity of Earth, though, we might
15:37 - maybe - stand a chance.
15:39 And that's what would happen if a black hole appeared on Earth.
15:43 What do you think?
15:44 Is there anything we missed?
15:45 Let us know in the comments, check out these other clips from Unveiled, and make sure you
15:48 subscribe and ring the bell for our latest content.
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