Black holes are quirky. They're so mysterious even Stephen Hawking says that much of what we know about them is probably fundamentally wrong. But what we do know is they have so much gravity, not even light can escape. And they can be as small as a single atom, but still have the mass of a mountain. They epitomise 'the fear of the unknown', they are one of the strangest, bizarre and peculiar thing in existence but don't worry – you all would be able to sleep a little easier after reading this post which explains black holes from the birth until death.
PREPARATION
OF A BLACK HOLE FROM A STAR
So
let’s start by talking about suns, which are really just super-hot balls of
mostly hydrogen collapsing through the sheer weight of their own gravity. In
their core, nuclear fusion crushes hydrogen, into helium releasing a tremendous
amount of energy. This energy in the form of radiation pushes against gravity
maintaining a delicate balance between two forces. As long as there is fusion
in the core, a star remains stable enough. But for stars with way more mass
than our own sun the heat and pressure at the core allow them to fuse heavier
elements until they reach iron Unlike the elements that went before, the fusion
process that creates iron builds up at the center of star until it reaches a
critical amount and balance between radiation and gravity is suddenly broken.
The core collapses within a fraction of a second and the star implodes. At this
very moment that all the heavier elements in the universe are created as the
star dies in supernova explosion. This produces either a neutron star or a if
the star is massive enough the entire mass of core collapses into a black hole.
Now
the question arises what would we see in a black hole, and the fun part comes
here, actually we can’t actually see a black hole. Instead we see nothing no
stars, no reflection-even light is swallowed up. So we just see a black sphere
reflecting nothing but if event horizon is black part. What is the hole part of
black hole? It is singularity (already discussed in my previous post i.e. Big
Bang).
WHAT
HAPPEN IF YOU FELL IN A BLACK HOLE?
If
you were to be sucked in beyond (Event Horizon) that, you’d have to be
travelling faster than the speed of light to escape which is next to impossible.
But having said that, black holes don’t actually suck things like a vaccum cleaner.
The
experience of time is different around black holes. From the outside you seem
to slow down as you approach event horizon. So time passes slower for you, at the
same point, you would appear to freeze in time slowly turns red and disappear.
While from your perspective rest of universe is in fast forward kind of like
seeing into the future. Sounds very interesting. Right now we don’t know what
happens next. But we think it could be one of two things.
One
you die a quick death. A black hole curves space so much that once you cross
event horizon, there is one possible direction. It is like being in a really
tight alley that closes behind you after each step. The mass of black hole is
so concentrated, at some point even tiny distances of a few centimeters would
mean that gravity acts with million of times more force on different parts of
your body. Your cells get torn apart, as your body stretches more and more
until you are a hot stream of Plasma. Two you die a very quick death, very soon
after you cross Event Horizon, you would hit a Firewall and be terminated in an
instant. Though neither of these options at particularly pleasant.
SPAN
OF YOUR LIFE IN BLACK HOLE
How
soon you would die depends on mass of black hole. A smaller black hole could
kill you before you even enter its Event Horizon, while you probably could
travel inside supersize massive black hole for quite a while. As a rule of
thumb, the further away from the singularity you are, the longer you live.
FLAVOURS
OF BLACK HOLE
Black
holes come in different sizes there are Stellar black holes with a few times
the mass of the Sun and diameter of an asteroid.
And
then there are supermassive black holes, which are found at the heart of every
Galaxy and have been feeding for billions of years.
Currently
the largest supermassive black hole known is “S50014+81” .It is 40 billion
times the mass of our Sun and 236.7 billion kilometer in Diameter which is 47
Times the distance from the Sun to Pluto.
DEATH
OF BLACK HOLE
As
powerful as black holes are they will eventually evaporate through a process
called Hawking Radiation. And it is quantum mechanics that holds the answer to
how black holes die. To understand it let’s look at empty space.
In quantum mechanics, subatomic positive particles and negative antiparticles pop into existence all the time in empty space. Since the positive particles have positive mass and the negative antiparticles have an opposite negative mass, they cancel each other out, and nothing really significant actually happens. But what if these particles and antiparticles came into existence right next to a black hole? What happens then? Do they do the same cancellation?
Famed
English physicist Stephen Hawking theorized that something different happens
around a black hole. The idea is that particles and antiparticles may not be
able to automatically cancel each other out because the black hole's gravity
pulls the negative antiparticle into black hole-oblivion. This process leaves
the positive particle alone and "uncancelled," making it
"real." These positive particles then, are emitted from the black
hole. The phenomenon is called Hawking Radiation.
But
that's not the end. After a long time, the black hole would lose mass due to
the gradual addition of antiparticles. As Hawking says, the black holes would
evaporate. During evaporation, the black hole emits energy in the form of the
positive particles that escape. The more massive the black hole, the more
energy would be released. Over time, the black hole would eventually lose so
much mass that it would become small and unstable. This is the dramatic end.
The black hole would then lose the rest of its mass in a short amount of time
as abrupt explosions—we can detect these explosions as gamma ray bursts.
But
this process is incredibly slow. The biggest black hole that we know might take
a googol (10^100) years to evaporate and nobody would be there to witness it.
I
hope now you might be much more clear with this post. Thank you for reading
this POST and I will soon come up with more posts on cosmology. Please comment
if you find something lacking or have some questions.
