- 10 hours ago
If you've always dreamed of time travel, here's your chance! We're gonna get inside a black hole and find out how time stops there. You can freeze time just by getting to the center of a black hole. It's a place where all conceptions of time and space completely break down. How does it work? Learn more about black hole in our video!
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00:00We're traveling a thousand light-years from our planet to an unfamiliar system.
00:05Here, there are two bright stars orbiting close to each other.
00:08But there is one small but very massive thing here as well.
00:12A black hole.
00:14These objects are mysterious and dangerous.
00:18They're capable of swallowing our entire world in one second without even noticing it.
00:23Even more, they can tear apart a huge star like our sun.
00:27And it's these giants that usually lie at the centers of galaxies.
00:32They're so heavy that their gravity holds countless stars, planets, and stardust around them.
00:37They can weigh millions or even billions of times more than the sun.
00:41And now, you're back on the ground at a rocket launch pad on Earth.
00:46All you can think about is holding your breath and jumping into the heart of that black pearl.
00:51But you don't have to hold your breath because you'll be in a spacesuit.
00:55And the oxygen is included free of charge.
00:58Besides, you're not likely to ever make it to the black hole.
01:02A trip that far with the technology we have now would take tens of thousands of years.
01:08Back to your garage where you stashed your hyper rocket, which will take you to the black hole in seconds.
01:14And you're next to two stars in a black hole.
01:18First thing you notice is that the black holes aren't black.
01:22Its gravitational force pulls in not only objects, but even light itself.
01:26This makes the hole invisible.
01:29You can only see a bright ring around it.
01:31That's called the event horizon.
01:33It consists of twisted light, hot dust, plasma, and pieces of asteroids that are also trapped there.
01:40So, the event horizon is the first obstacle to overcome.
01:44Okay, you put on your jetpack, open your rocket's door, and jump towards the black hole.
01:50The force of gravity begins to pull you quickly toward it.
01:54The spacesuit protects you from the enormous temperatures and levels of radiation on the event horizon.
02:00Conventional protective gear would hardly help you.
02:02So, you thank your dad for stashing this super powerful protective suit in your garage as well.
02:09You begin to feel like your body's stretching unpleasantly.
02:13The problem is that gravity increases with every inch closer to the center of the black hole.
02:18And it's much stronger at your head than at your feet.
02:21Your body starts to stretch like spaghetti.
02:25That's why it's called spaghettification.
02:27No suit can protect you from that.
02:30And there isn't a single spaceship that can withstand that kind of strain.
02:34Well, this was a short video.
02:37Okay, let's rewind to the moment before the night.
02:41You realize that to get to the heart of the black hole and survive,
02:44you don't need improved equipment, but another black hole.
02:49And it's the size and weight of it that matters here.
02:53Theoretically, you can survive falling into a supermassive black hole.
02:57It's all about the width of the black hole's event horizon.
03:01When a hole is small, about the weight of our sun, the event horizon is small too.
03:06And then its edge is remarkably close to the center of the abnormal gravitational force,
03:12which would make you spaghettified quickly and brutally.
03:16But if the event horizon is wide, it's farther from the center of the gravitational force.
03:22Then the difference of gravity pressing on your head and feet will be non-existent.
03:27So if you have enough air in your spacesuit, you can survive such a journey.
03:31So, you must pick a supermassive black hole.
03:35Hmm, let's see.
03:37One at the center of the Milky Way?
03:39No, there's too much hot plasma and debris around it.
03:43You need a completely isolated black hole for a jump like this.
03:47Somewhere in dark space where it hasn't had time to gather the debris of neighboring worlds around it.
03:54You quickly open your space map and find such a black hole.
03:59One faster-than-light trip, and you've arrived.
04:02There it is.
04:03A huge start, nothing.
04:05There's only distorted light from distant stars and galaxies on its event horizon.
04:10To test your theory, you throw a mannequin into it.
04:14It approaches the black hole and then slows to a standstill.
04:18But it's just an illusion.
04:21The black hole is so heavy, it can warp both space and time.
04:25So, to the observer, the dummy is frozen in the event horizon.
04:30But it has long since entered its heart.
04:33The dummy didn't get spaghettified like you did when you fell into a small black hole.
04:38So now, you're confidently jumping after it.
04:42Remember that even if you feel fine, it's still a one-way trip.
04:46Once in the black hole's field of attraction, nothing can escape its embrace.
04:51No matter how powerful a rocket you have or how hard you flap your arm.
04:56You're now at the edge of the accretion disk.
04:59Every second here equals weeks or months on Earth.
05:02You're traveling through time.
05:04Our home planet may already have flying cars and skyscrapers several miles tall all over the place.
05:11But for you, it's only a couple of minutes.
05:15Whoa!
05:16All the light you see from the stars has turned red.
05:19That, too, is because of gravity.
05:22The light we see is waves.
05:24But the black hole stretches them out.
05:27The short wavelengths of blue become long and red.
05:31Great!
05:32You've passed the event horizon and are now heading into black nothingness.
05:36You look up and see a thin ray of light.
05:40The last thing you see, in fact.
05:41After that, there's just black void.
05:44No one knows what happens next.
05:47Some theories say black holes can be portals to another dimension or to another place in the universe.
05:53By jumping into a black hole in our galaxy, you can jump hundreds of thousands of light years away from
05:59our home.
06:00In that case, you will experience your fall in reverse.
06:04First, you see a small but expanding beam of light.
06:07Then, red starlight returns to blue.
06:11And before you know it, you're back on the event horizon.
06:14And soon after, you're free of the black hole's pool.
06:18But scientists still can't confirm this theory.
06:21Okay, that's too grim.
06:23So, just this time, we'll bring you back to Earth in the company of your friends.
06:28They praise you for your accomplishment of surviving the center of a black hole.
06:33Now, you're the heart of the company, and no black hole can scare you.
06:38But even the biggest black hole in space isn't as scary as you might think.
06:43They have a lifespan.
06:45That radiation I mentioned takes energy from the black hole.
06:49If it doesn't have food around it, the hole starts to deflate like a balloon.
06:54And eventually, there's nothing left.
06:57Another fear around black holes is that we can create one at home.
07:02Indeed, inside the Large Hadron Collider,
07:05scientists conduct experiments with small particles colliding at high speed.
07:10There are huge bursts of energy.
07:12And some scientists believe this energy is enough to create a microscopic black hole.
07:17It will begin to absorb its surroundings and grow.
07:21First, some small objects in the room where it was created.
07:25Then, the entire lab.
07:27The hole continues to grow and is already consuming our whole planet.
07:31It changes the balance of power in our solar system and absorbs the planets one by one.
07:38When those are finished, it's time for dessert.
07:41The sun.
07:41The light upper layers of plasma are stretched into long spaghetti and pulled toward the black hole.
07:49Then, layer by layer, our star collapses into the dark abyss.
07:54When the sun is half-absorbed, the black hole shoots a beam of energy and light outwards
07:59and continues to consume the sun.
08:02In mere moments, there's nothing left of our solar system.
08:06That's how some people describe the end of the world.
08:08But even if we do manage to create a microscopic black hole, we'll be safe.
08:14It'll be too small to absorb big objects.
08:16And it will only feed on small atomic particles.
08:19Black holes emit energy as well as consume it.
08:22So our little one won't have time to grow.
08:25It'll lose more than it finds in a fraction of a second.
08:29So what you'll see is a momentary flash and then nothing.
08:33Although creating a stable and controlled black hole may even be useful.
08:38They emit enormous amounts of energy that we can use.
08:41A black hole, the mass of Mount Everest, could power all of humanity.
08:47Of course, black holes are still dangerous.
08:50But we can watch them and study our universe.
08:53If we stay far enough away, of course.
08:56So, you decide to put a padlock on that garage door.
09:00For now.
09:03So, you're standing on a diving board in the middle of an open space.
09:07You look down, but that's not a pool.
09:10It's a giant black hole.
09:12Well, what the heck.
09:13You start swinging and then you jump.
09:16The gravity of the black hole grabs you.
09:18And you pick up speed.
09:20Just a little more and you'll enter the dark abyss.
09:23But you're not afraid.
09:25You're sure you can survive the fall into the black hole.
09:28Besides, you have a clear goal.
09:30To travel through time.
09:32But first, let's figure out how it works and why time stops near a black hole.
09:37This is the space-time grid.
09:38It's what our entire universe is made of.
09:41And just like a regular grid, it sags if you put something heavy on it.
09:45Like me.
09:46For example, let's put the planet Earth here.
09:49You see a little funnel that is formed around the Earth.
09:52And if you put a small ball next to the planet, it'll roll into the funnel.
09:56That's how gravity works.
09:58The heavier the object, the more it bends space-time.
10:01By comparison, here's the Sun.
10:03It's almost 333,000 times heavier than the Earth.
10:07So, it makes a really big funnel.
10:10So big that all the planets in our solar system move around that star inside that funnel.
10:15So now, let's put a black hole on a space-time grid.
10:19Its centers are infinitely heavy.
10:21So, they create a limitless deep well.
10:24And anything caught in the black hole's gravitational field can never leave it.
10:28Not even moving at the speed of light.
10:30Okay, their gravity is infinitely strong.
10:33But why do they slow down time?
10:35It's all about the speed of light.
10:38According to physics law, the speed of light must be the same at every point in our universe.
10:43Even in a black hole.
10:44So, for our experiment, we take this ball, a photon of light that can travel 671 million miles per hour.
10:52You could get from Earth to the Sun at that speed in 8 minutes.
10:55That's how long it takes light to travel from our star to our eyes.
10:59So, when you're looking at the Sun, you're looking back in time 8 minutes ago.
11:03By the way, don't look at it directly.
11:06Now, the critical thing to remember here is that velocity consists of two physical quantities.
11:11Space, miles.
11:12And time, hours.
11:14We'll use that later.
11:15Now, let's look at the black hole in our space-time grid.
11:18In three-dimensional space, it appears like this.
11:22But if we assume that space is two-dimensional, our grid looks like this when viewed from above.
11:28Just a lot of squares.
11:29And this is the black hole right in the middle.
11:32If you look at the grid from the side, you'll see a straight line.
11:36And the black hole here looks like a pit.
11:38Or like an endless well.
11:40Now, let's follow our photon of light in three-dimensional space.
11:44Here, it's moving toward the black hole.
11:46And then, it falls into the well of the black hole.
11:49And it continues its motion at a constant speed.
11:52Now, the side view.
11:53Again, the photon moves from left to right and then falls.
11:58Its velocity doesn't change.
12:00The problems begin if you look at the experiment from above.
12:04When the photon of light moves in the distance of the black hole, its speed is stable.
12:08But then, it goes down into the well.
12:10First, it slows down.
12:12And then, it just stands still.
12:14But it's moving downwards.
12:16The photon moves in an arc down the well in the lower dimension without changing its speed.
12:22But in the higher dimension, it traveled a minimal distance at the same speed.
12:26Usually, this would mean that the photon was moving at a low speed in the second case.
12:31But not in the case of the speed of light.
12:34Remember, it must be the same at every point in the universe.
12:38The number 671 million miles per hour shouldn't change.
12:42So, we change the very parameters of that number.
12:46Time.
12:47Time itself must slow down so much that this slight movement of the photon, when you look
12:52at it from above, was at the same speed.
12:55671 million miles per hour.
12:57But if you go down and look at this well much lower, you see that its walls are almost vertical.
13:03So, a photon of light would be moving in a vertical trajectory.
13:07That means that if you look at it from above, the photon will just be standing still.
13:12Again, its velocity can't change.
13:14So, time will vary.
13:16At that point, it should just stop.
13:18This is what happens near a black hole.
13:21Now, if you look at a black hole, you can see this effect in action.
13:24It swallows up the light around it.
13:27But as for an observer, it seems to you that the light stays in orbit around the black disk.
13:32In fact, at that moment, the photons are still moving at the speed of light inside the black hole.
13:38It's because time has slowed down there so much that you feel like the light has stopped there.
13:44This disk is called the event horizon, the point of no return, the last stop before you go into the
13:51black abyss.
13:52And at the very center of the black hole is the singularity.
13:56This point of space is so dense that if you try to describe it with any numbers or physical quantities,
14:02they would all tend toward infinity.
14:04Simply put, all the laws of physics we know just stop working here.
14:09So, scientists can't say exactly what awaits you in the singularity.
14:13Before you make that jump into the black hole, let's drop a space probe there with a blue light that
14:19flashes once per second.
14:21And let's attach giant clocks to it.
14:23You see the probe falling into the black hole, gaining speed.
14:27But then it starts to slow down.
14:29Moreover, the probe flattens out and seems to spread out around the black hole.
14:34And then, you notice that the blue beacon on the probe has changed its light.
14:39It now flashes as red.
14:41It's because the light is a wave.
14:44Blue is a truly short wave with a high frequency.
14:47But the black hole's gravity acts on this wave, stretching it out.
14:51The light waves get lengthened and become broader and less frequent.
14:54The new wavelength and frequency match with the red color.
14:58It's called red shift.
15:00Also, the probe blinks now not once a second in short beeps, but lights up and goes out for a
15:06long time.
15:07It's because of the time warp.
15:09If you, as an observer, look at the clock on the probe, the second hand there barely moves.
15:15However, the clock on your hand works as usual.
15:18But if you could be in a black hole, time would seem normal to you.
15:23And the arrow on the clock would move as it did before.
15:26But the hands on the clock outside the black hole would move like crazy to you.
15:31That's because time goes much faster outside the black hole.
15:35Oops, your probe just got ripped apart.
15:38That's because of the substantial difference in gravity that acts on the probe.
15:42The black hole's gravitational force increases with every foot of approach.
15:47That is, if you were to extend your hand toward the black hole heart, the gravity on your fingers would
15:53be much stronger than on your shoulder.
15:55This force would cause your fingers to lengthen, simply like spaghetti.
16:00That's why many people think it's impossible to survive falling into a black hole.
16:05But scientists think you could survive without a problem.
16:09Hey, maybe they should jump first just to make sure.
16:12The thing is, you have to pick a black hole as big as possible, like the ones at the centers
16:17of galaxies, for example.
16:19That bright spot at the center of the Milky Way also has a black hole.
16:23It's about 1 million times heavier than the sun.
16:26And this is the Messier 87 galaxy, one of the most massive galaxies among our neighbors.
16:32In 2019, humanity got its first-ever photo of the black hole at the center of this galaxy.
16:38It's about 6.5 billion times heavier than our sun.
16:42So, it's the perfect place to make your jump into a black hole, finally.
16:46Let's go!
16:47At first, you feel a strong acceleration as the incredible force of gravity grabs you.
16:53But in the case of a supermassive black hole like this, the gravity doesn't change as dramatically.
16:59That's because of its size.
17:00Right now, the gravitational force on your legs is about equal to the gravitational force on your head.
17:06So, you don't turn into spaghetti, and you feel comfortable.
17:10You see that the light from the stars and all the space around you has begun to shrink at a
17:15certain point.
17:16It means that you have already passed the event horizon and are now moving toward the black hole's heart.
17:22As a result, the light of the universe becomes a small dot for you and then disappears altogether.
17:29If we look at our space-time grid, you're already falling into a well.
17:33Time has completely stopped for you.
17:36However, the rest of the world continues to move steadily through time.
17:39If you could now look at the Earth from a black hole, you would see a time-lapse.
17:44An accelerated video of how the months and years go by on our planet.
17:48If you had a jetpack that had an incredible engine to pull you out of the black hole, then you
17:54could make a jump forward in time.
17:56In one second, centuries on Earth could pass in the heart of a supermassive black hole.
18:02But this only works one way.
18:04You can't go back in time.
18:06But for now, you keep falling into the black hole.
18:09Beyond that, no one knows what'll happen to you.
18:12We only have theories about wormholes and white holes that might transfer you somewhere else in the universe.
18:19So, enjoy your trip and just think about all the frequent flyer miles you're racking up.
18:36Black holes are like omnivores.
18:39They'll eat anything in their way if it gets close enough, including planets, stars, clouds of gas, or some very
18:46unfortunate intergalactic travelers.
18:48Not that it really gets hungry and goes after space objects.
18:51It simply swallows whatever comes nearby.
18:54It stretches giant space bodies until they're thin like spaghetti and rips them apart atom by atom.
19:02A black hole is a huge amount of matter that comes in a very small package.
19:06It's like you squeeze a star ten times bigger and more massive than the sun into a small area with
19:13the diameter of New York City.
19:14You get an extremely massive, compact, and dense pit.
19:18With gravity so strong, not even light can escape.
19:22Not even another black hole.
19:24They don't have a fixed point in space.
19:27Stars, planets, asteroids, comets, black holes, and everything in the universe is in constant motion.
19:34That's why things get so chaotic from time to time.
19:39Researchers found a giant black hole at the heart of one galaxy being eaten by an even bigger one.
19:45A black hole can get extremely big.
19:47At the centers of most giant galaxies are black holes that can grow millions to billions of times the mass
19:54of our sun.
19:55One of the ways to become so big is by eating others of its kind.
19:59A black hole merging with another black hole is one of the most energetic and powerful things in the universe.
20:06Picture this.
20:071.3 billion years ago, two black holes are circling around each other.
20:12The bigger one pulls the smaller black hole inwards, and now they're locked together in a spiral.
20:18Through time, that orbit starts decaying, but very, very slowly.
20:23These two black holes are constantly getting closer and closer.
20:29As they approach one another, the disks of orbiting dust and gases that surround them mix and create an intense
20:36towering vortex.
20:37It extends and goes pretty high above the center of that disk.
20:41At some point, they finally merge into one extra big, supermassive black hole.
20:47As they're merging, they kick out gravitational waves.
20:50These waves tell us a lot about black holes, but they can't reveal their precise position.
20:57So, scientists need some electromagnetic signal that will find the black hole's location, like radio waves, x-rays, or a
21:05flash of light.
21:06We can't see black holes, but we can detect their effect on space objects that are surrounding them.
21:11When a black hole passes through a cloud of matter, its strong gravity will pull matter inward.
21:17If a star or a planet comes close enough, the same will happen.
21:22The attracted matter then accelerates, which means starts to move very quickly and heats up.
21:28The black hole then starts emitting x-rays that radiate in the area surrounding it.
21:33The energy of x-rays affects the neighborhood and can, for example, spur the growth of new stars.
21:40And finally, BAM!
21:43They collide!
21:43It's a massive burst of energy, one of the biggest bangs ever since the Big Bang.
21:49In less than a second, that collision emitted more energy than all of the stars in the visible universe together
21:55at the same time.
21:57Black holes can become huge, but not necessarily.
22:00Stellar-mass black holes have a mass similar to the Sun, and they can be very small.
22:05The one scientist found in 2019 is located 10,000 light-years away from us and is only 12 miles
22:12across.
22:13They really have a reputation for destruction, but black holes are just another source of gravitational force, similar to stars.
22:22That means it's possible for a space body to orbit them, if it moves fast enough, of course.
22:27Let's say there's a black hole with the same mass as the Sun.
22:31The speed a space body would have to move at is the same as the one needed to orbit our
22:36Sun, if the distance is the same.
22:40That's a theory.
22:43In reality, planets don't really orbit black holes, because those that have a mass similar to our parent star are
22:51mostly the remnants of giant stars that ran out of nuclear fuel and eventually exploded.
22:57That's how black holes are created in the first place.
23:00And chances are that none of those planets nearby will survive it.
23:05But, 30 years ago, scientists discovered the first planets beyond our solar system.
23:12These planets were found orbiting a pulsar, which is also some sort of supernova remnant.
23:18We don't know how they survived the explosion of their parent star.
23:21It's possible they may have been created after the destruction, from debris that formed after the explosion.
23:28Scientists even have a theory that black holes are possibly wormholes, something like tunnels to other galaxies.
23:35That means they don't destroy objects they swallow, but send them somewhere.
23:39The theory says the object that enters and then goes out on the other side leaves the tunnel through something
23:46opposite of the black hole, a white hole.
23:48It probably looks similar to its companion, with all that spinning and similar mass.
23:54There could be a ring of gas and dust around the event horizon.
23:58The event horizon is the point of no return, the part of a black hole where nothing escapes.
24:03Unlike a black hole, a white hole lets light and all the matter leave, but none of that will be
24:09able to enter the portal once again.
24:11About 50 years ago, Stephen Hawking realized that black holes leak energy.
24:16Scientists then developed the theory that a white hole could be born out of a black hole.
24:21They're still not sure how the black hole disappears, but in this scenario, it would grow so small, it no
24:27longer can have such strong gravity that makes it swallow other objects.
24:31So, it might turn into a white hole then.
24:36Such a hole would be similar in mass to something really light, like human hair.
24:41It wouldn't be so dramatic as its black hole ancestor, but it would still hide mysteries in its interior, the
24:48information of all space objects it had swallowed previously.
24:51It would eventually spit out that information and get so big, it would dominate the universe.
24:57White hole behavior, opposite of black holes and all that sucking the matter inward, could be compared to the Big
25:03Bang explosion, where the universe is expanding and new objects are forming.
25:08But even if something like this happens, it may only be possible trillions of years from now.
25:14And there's an issue.
25:16Even if some big white holes did form somewhere in space, they probably wouldn't last too long.
25:22Outgoing objects would collide with the matter in orbit, so the whole system would collapse and turn into a black
25:28hole once again, since they're also formed after supernova explosions.
25:32Stars, asteroids, comets, galaxies, and planets, all those space things we can see, make up nearly 5% of the
25:40universe.
25:41About 25% could be dark matter, a mysterious substance we can't actually see, but assume it's there because everything
25:49in the universe moves to its gravitational tune.
25:52This dark matter is kind of like a spider's web.
25:56It holds all those galaxies that move pretty fast together.
26:00Its evil twin is called antimatter.
26:04Antimatter particles are like the opposite version of the matter, the same mass but opposite electric charge.
26:10When they collide, antimatter wipes out the regular matter, and the result is pure energy.
26:17Dark matter probably makes the universe expand even faster than it used to do.
26:21One of the latest theories says it could be responsible for the huge asteroid strike that made the dinosaurs go
26:27extinct, too.
26:28The universe doesn't have a center, but galaxies do.
26:32The Earth makes a circle around the center of the Milky Way once every 250 million years.
26:38This orbit is not straightforward, but we can roughly predict it.
26:42Once in every 60 million years, we go through the crowded region of our galaxy known as the Galactic Disc.
26:49At the same time, we can track some harsh mass extinctions in the history of our planet, including the asteroid
26:55that wiped out the dinosaurs about 66 million years ago.
26:59Professor Rampino from New York University proposes that dark matter has a gravity that could throw nearby space bodies into
27:07the Earth's path whenever we enter the Galactic Disc.
27:10That means some asteroids and comets that would usually be far away from us are flung towards our planet.
27:17The biggest thing in the universe, at least the one we know about, is the Hercules-Corona Borealis Great Wall.
27:24It's a cluster of galaxies 10 billion light-years across, bound together by gravitational force.
27:29The biggest elliptical galaxy is IC 1101, and has a diameter of 4 million light-years.
27:37The smallest galaxy, Segway 2, we've discovered so far, has a diameter of a little bit over 220 light-years.
27:45It's pretty faint, and has only 1,000 stars.
27:48For comparison, our galaxy has 100,000 million stars.
27:53It orbits the Milky Way.
27:56For comparison, our galaxy has 100,000 million stars.