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0:05 Hello, everyone, I'm Dmitiry Pobedinskiy, and I am happy
to welcome you to the channel QWRTΥ
0:09 And today we'll talk about black holes,
0:12 mysterious space objects
0:14 absorbing all matter around them.
0:17 But anyway,
are they so terrible?
0:19 Let's sort it out.
0:21 How are black holes built?
0:22 Where do they come from?
Is it possible to make a black hole from a donut
and is it scary fall into it? A black hole is
0:28 an object the gravity of which is so
0:31 enormous
0:32 that any object thrown up from it
0:35 with whatever huge velocity
0:37 will not fly away into the space,
0:40 but will inevitably be attracted back.
The maximum speed
in the Universe is that of light, but
even light cannot overcome
3:11 the gravity and
0:49 and escape from the black hole. So how
are black holes born?
In most cases, it's quite the contrary. They are not babies,
they are small corpses of
dead stars. What is a star?
It's a huge ball
a huge ball of hot gas
1:05 Its own forces of gravity
1:07 try to squeeze it.
1:09 These forces are opposed by the forces of inner
1:12 pressure that arises due to
enormous temperature caused by nuclear fusion reactions
in the center of the star. It is like
1:19 a party balloon.
1:20 The pressure of the air expands it from inside, but
1:22 the tension of the rubber membrane holds it.
1:25 The star dies when it
1:27 runs out of fuel.
Then the expanding force disappears,
1:32 and the star begins to shrink.
1:34 At this, its density is increasing, and the gravity
1:38 around it is becoming stronger and stronger.
And if it shrinks to the radius less than
1:43 what is called
1:45 the Schwarzschild radius, or
1:46 the gravitational radius, then its density
1:49 will be so enormous
1:51 that it will become a black hole. In fact,
1:54 any object has this radius.
1;56 If we take a person and compress him
in some mysterious way
to the size of
2:02 one 20 billionth of that of an electron, then
2:05 this person will become a black hole.
You can take a donut, iPhone, the Eiffel tower,
or even Justin Bieber, and squeeze
any of those to a certain
size,
2:15 and you'll get a small black hole.
2:17 Our planet should be compressed to the size of a cherry,
2:19 and the Sun, to a ball with a diameter
2:22 of 6 kilometers.
2:24 So far we do not know how to do this
The only thing we know is that
stars of the mass more than three masses of our Sun
may shrink to the gravitational radius
on their own, under the influence
2:36 of their own gravity
2:37 This is why we believe that the black holes
2:39 can be created by stars.
2:41 But what is inside of the black hole?
2:44 How is it built?
2:46 Under the colossal
3:11 gravity
and will inevitably fall on it.
2:52 Just imagine trillions
2:54 of quadrillions of kilograms
in a single point.
It means that they have
infinite density.
We call this a singularity. Any object
that approaches the singularity
by a distance less than
the gravitational radius
won't be able to cope with its huge
3:11 gravity
3:12 and will inevitably fall on it.
3:15 That is, around a singularity there is
3:17
an area, from which there is no way back.
20 It is limited by the so-called
3:22 event horizon,
3:23 and this, in fact, is the boundary of a black hole.
What if you fall into a black hole?
black hole
3:29 Let us first consider what your
3:31 good buddy can see from some distance.
According to the general theory of relativity,
in the areas with strong gravity
the time is slower than
in the areas
3:41 with lower gravity
3:43 therefore, from the side it will be seen that while
you are approaching the event horizon,
your speed is decreasing,
3:50 you are slowing down and finally
you stop near the event horizon
3:54 Your partner will never see you
3:57 crossing the event horizon,
3:58 because from his point of view,
4:02 your time has stopped.
4:04 Besides,
The light reflected from you
is showing stronger redshift
4:10 and is fading.
4:11 So eventually you will completely
4:13 disappear
from the perspective of your partner. But for you
4:17 things will be much more interesting.
4:19 Time will go as usual,
4:21 and, if a black hole is big enough, you will
cross the event horizon
without noticing anything particular.
4:28 Just there will be no way back.
will be
4:30 Another thing is that sooner or later you will
start turning into spaghetti.
4:35 This is because the gravitational field
4:37 around a singularity is extremely
4:39 non-uniform.
4:40 The closer you are to it, the stronger is the field.
4:43 It turns out that, for example, your legs
4:45 will be attracted much stronger
4:47 than your head, and you'll feel
4:49 being stretched.
4:51 The tension will be so strong,
4:53 that it will tear your apart before
you get close to the singularity.
58 Instead of stretching, scientists decided to call this
in a creative manner – spaghettification.
But
5:03 But when atoms, of which you are composed,
will finally fall on the singularity –
what will happen to them
is so far a mystery
But I think it won't matter to you anymore.
5:13 Surely, there is no need to be afraid of black holes,
as their number in the Universe is huge
5:19 They are centers of galaxies, and quasars, and different objects
5:22 in deep space, and... ladies' handbags. :-)
5:24 They are either very far away from us,
5:26 or harmless enough, but in either ca
5:29 they hide a lot of mysteries and
unsolved problems. That's all. Put your "likes"
5:34 and subscribe to our channel in order not to miss
5:36 new videos.
5:38 And thank you for watching.