Hawking theorized that the area of black hole
would always increase ,or remain same but
never decrease.
In fact, the area would
increase whenever matter ,or radiation fell
into the black hole.
Or if two black holes collided and merged
together, the area of the final
black hole would be greater than, or equal
to the sum of the areas of the original black
holes
Entropy Relation
Now, Entropy, measures the degree of disorder
of a system.
Disorder tends
tend to increase if things are left to themselves.
Stop making repairs around the house and watch
it collapse.)
[Visual of house breaking with time]
A precise statement of this idea is known
as the second law of thermodynamics.
It states that the entropy of an isolated
system always increases.
Violating second law.
However, if one has a
black hole around ,there seems to be a rather
easier way of violating the second law: just
throw some matter with a lot of entropy, such
as a box of gas, down the black hole.
The total entropy of matter outside the black
hole would go down.So the observers outside
must also consider the entropy of the black
hole for the Second Law to hold.
The nondecreasing behavior of a black hole�s
area was very similar to the behavior of
Entropy
Because of the similarity, of non decreasing
behavior between entropy and area of black
hole, a research student named Jacob Bekenstein
suggested that the area of the event horizon
was a measure of
the entropy of the black hole.
This suggestion seemed to prevent the second
law of thermodynamics from being violated
in most situations.
However, there was one fatal flaw.
If a black hole has entropy, then it ought
to also have a temperature.
Every body with a particular temperature emits
radiation at a certain rate.
if you heat something in a fire it glows red
hot and emits radiation, but bodies at lower
temperatures emit radiation too; we do not
notice its very little.
This radiation is required in order to prevent
violation of the second law.
So black holes ought to emit radiation.
But how would black hole emit radiation?
Heres where hawking comes in.
Space is not truly empty.There are quantum
fluctuations.There are virtual particles popping
in and out of existence.Once in a while.
Near the event horizon of black hole.one of
the particles falls in and the one outside
becomes a real particle.These tiny streams
of escaping particle is known as hawking radiation.The
particles that fell into black hole have negative
mass and would shrink the black hole until
it disappears.
