10 Fascinating Facts about Black Holes
10.
Three Types of Black Holes
The first type of black holes is called stellar
black holes and they are the smallest of the
trio.
They are created when a star that is larger
than our sun collapses and continues to fall
in on itself.
While stellar black holes are relatively small,
they are incredibly dense.
For example, three times the mass of the sun
can be packed into the area that is the size
of a city on Earth.
It is believed that there are about a few
hundred million stellar black holes in our
galaxy.
On the other end of the size spectrum are
supermassive black holes.
Researchers aren’t sure how they are spawned,
but their radius is about the size of the
sun and their masses are billions of times
greater than the sun.
It is believed that they are at the center
of galaxies, including our own.
Finally, intermediate black holes are mid-sized
black holes.
It is believed they are formed when there
is a chain reaction collision of stars that
are in a cluster.
Researchers weren’t even sure that these
existed until one was discovered in 2014.
9.
What Do they Look Like?
Black holes can’t be observed because nothing,
not even light, can escape from their boundaries,
known as the event horizon, because the gravity
is so strong.
What we could observe is gas when it falls
into a black hole because it is heated up
which causes the gases to glow.
If we had telescopes or satellites to see
a black hole up close, it would look like
a rotating disk with a black hole in the middle.
8.
Colliding Black Holes
On September 14, 2015, twin Laser Interferometer
Gravitational-wave Observatory (LIGO) detectors
picked up a small chirp from space.
It turns out that chirp was a collision 1.3
billion light years ago between two black
holes a billion light years away.
The black holes were about 29 and 36 times
the mass of our sun.
Before colliding, they circled each other
and then in a fifth of a second, they became
one black hole with the mass of 62 of our
suns.
When they combined, some of the mass was converted
to energy and the energy emitted was gravitational
waves.
Gravitational waves were first theorized by
Einstein, and they are a disturbance in the
cosmos that could cause space-time to stretch,
jiggle, and collapse, which would produce
ripples of gravity.
The problem was that there was no way to detect
these gravitational waves and physicists,
including Einstein himself, were never really
sure they existed.
The discovery has already been hailed as one
of the biggest scientific breakthroughs of
the past century and Stephen Hawking said
it is a key scientific moment that could change
how we look at the universe.
7.
Times Slows Down Around it
If you’ve seen Interstellar, you’ll know
what happens when you travel near a black
hole; time slows down.
What is incorrect about the film is that the
time dilation would not be quite that extreme.
Time dilation is ultimately affected by gravity,
the stronger the gravity, the stronger the
time dilation.
Also, time only slows down once you get near
the black hole, once you pass the event horizon,
time would stop.
6.
What’s at the Center?
It is believed that the very center of a black
hole is a time space curvature called singularity.
As you get closer to singularity, large amounts
of matter are crushed and jammed into immensely
small and dense space.
In fact, in singularity, matter is crushed
to the point where it doesn’t even have
dimensions.
Singularity also grows infinitely bigger the
further objects travel into it.
But since the insides of black holes are impossible
to observe, singularity is only a theory and
some physicists even question if it exists
at all.
5.
Closest Black Holes
Since black holes are so hard to detect, we
aren’t exactly sure where the closest one
is.
At first, researchers believed the closest
one was at the center of the Milky Way, but
currently it is believed that V616 Mon (A0620-00)
in the Monoceros constellation, about 3,000
light years away is the closest black hole.
4.
Energy Source
At first, it was believed that black holes
were just energy drains because once something
crosses the event horizon, it never leaves.
But in the 1970s, Stephen Hawking showed that
black holes should also emit power around
the event horizon through a radiation, known
as Hawking Radiation, and it is produced by
quantum fluctuations of empty space.
The obvious extension is - would we ever be
able to harness that power?
Well, some physicists believe that if we overcame
the physical problems it would be possible
to get energy from a black hole.
In 1983, a team of physicists suggested that
an energy collecting device could be dropped
in close to the event horizon and then we
could simply pull it back up.
It would be similar to getting water from
a well with a rope and bucket.
Obviously, you’d need a very strong bucket
and rope to avoid being sucked in by the event
horizon.
Another way to collect energy would be to
stick in “strings” and the radiation would
run up it, the way oil runs up a wick in a
gas lamp.
3.
Could We Create One?
It goes without saying that black holes can
be dangerous, so we definitely wouldn’t
want to make one on Earth, right?
Well, it turns out that we can theoretically
make microscopic ones that are harmless.
In 2014, using Hawking radiation, researchers
came close to mimicking a black hole in a
lab.
But at the time of this writing, one has not
been created.
2.
Evaporate Over Time
In the prior entries we talked about Hawking
Radiation, which is energy found at the boundaries
of the black hole.
What is interesting is that this radiation
also causes black holes to evaporate over
long periods of time.
Why they evaporate comes down to quantum theory
which suggests that virtual particles pop
in and out of existence all the time.
When they pop into existence, a particle and
an antiparticle combine and then they disappear
again.
But when the two particles pop into existence
near the event horizon, they don’t cancel
each other out.
Instead, one falls into the black hole and
the other goes off into space.
Over time, the escaping particles cause the
black hole to deteriorate.
Meaning black holes die, just like everything
else in the known universe.
1.
What Happens When You Fall In
If you were to dive into a black hole that
was the size of the Earth, your body would
look like “toothpaste” coming out of a
tube.
Your body would be stretched out in what British
astrophysicist, Sir Martin Rees, called “spaghettification.”
Eventually, you would become a stream of subatomic
particles that would swirl into the black
hole.
But, if you were to dive into a larger black
hole, say one that is the size of our solar
system, then your body may be able to hold
its structural integrity.
If you survive that, you’ll see the curvature
of space-time and you will be able to see
everything that fell into the black hole before
you and at the same time you’ll be able
to see everything that will ever fall into
the black hole.
This means that you’ll be able to see the
entire history of the universe, from the Big
Bang to the end of time, all at once.
