CASIMIR EFFECT AND HAWKING RADIATION
What is the Casimir Effect?
In 1948, a Dutch Physicist Hendrick Casimir came up with a
method to detect a tiny force caused by zero-point energy or also known as
vacuum energy exerted by virtual particles. To understand this phenomenon,
imagine a rigid reinforced crate with a vacuum inside of it, so that you would
expect for there to completely nothing within the crate. Now add 2 parallel
mirrors about 100 atoms apart from each other into the crate. The result of
this experiment is that the two mirrors miraculously end up moving towards each
other, clearing the gap that was previously put between them. This strange behaviour
completely questions our understanding of vacuums and whether vacuums are quiet
and empty.
What is causing this strange behavior?
In order to explain this phenomenon, we must look carefully
at Werner Heisenberg’s uncertainty principle, which states that you may not
know both the position and momentum or the energy and duration of a subatomic
particle to great accuracy (Δx Δp ≤ ℏ/2, ΔE Δt ≤ ℏ/2).
So as our values for these variables tend towards zero the uncertainty
also tends toward zero and hence according to the uncertainty principle
particles cannot have both zero energy and zero duration, leading to the fact
that particles which do not exist have a great chance of coming into existence
for a short period of time from quantum vacuum fluctuation.
These “virtual” particles occur in annihilation pairs
(antimatter and matter particle pair) and very quickly eliminate each other or
if you think of them as waves, they destructively interfere, cancelling each
other’s amplitudes out, which has been proved by Einstein’s equation E=mc^2 and
Planck’s constant, which lead to showing that particles can be modelled as
waves with wavelengths by De Broglie . Due to the fact that waves can have an
infinite amount of wavelengths, we know that there can be an infinite amount of
different waves in open space but in our crate, they must be a form of a
standing wave and harmonics of that a standing wave (which is still infinite)
in order to exist between our mirrors.
There is a greater probability of having more particles on
the outside of the mirrors than in between the two mirrors and these particles
can collide with the mirrors exerting a force on the mirrors. As there is a
greater net force pushing the mirrors together than the force pushing them
apart, they come together.
However, when attempting to calculate the mass and energy of
these particles, a lot of infinities were calculated so mathematicians had to
result in renormalization, which pretends that these infinities do not exist.
This effect is extremely useful in explaining Hawking radiation.
What is Hawking radiation?
After it has been detected that black holes emit radiation
and shine, Steven Hawking attempted to prove that black holes do not shine and
instead proved the opposite, by combining laws of quantum mechanics and general
relativity and found out that stuff can escape near the event horizon of a
black hole and that black holes do shine.
If an antimatter and matter particle pair is formed close to
the event horizon, there is a chance of one of the particles getting sucked in
by the black hole and the other one escaping so that they can no longer
annihilate each other. This escape particle has an energy that we can detect as
Hawking radiation. You would think that this violates conservation of energy
but as from our point of view, this escape particle has positive energy meaning
that the black hole must have gained negative energy, which is the same as the black
hole losing mass, which is equal to losing energy, so that ultimately energy is
conserved and the energy of the escaping particle is interestingly due to the
black hole losing mass.
Black Hole Explosion
This phenomenon can lead to black holes being drained and
decreasing in size. Hawking proved that as black holes evaporate by gaining
negative energy, they increase in temperature so that the smallest black holes
are the hottest ones. As the black hole’s mass decreases to zero, a powerful
explosion of gamma rays will occur, which subsequently causes the most powerful
eruption to ever be detected. This knowledge of black holes is due to the proof
of vacuum energy by Hendrick Casimir and the Casimir Effect.
