What is a white hole | Why white hole is compared with a black hole
A white hole, as the name indicates, is the opposite of a black hole. It is a hypothetical, celestial phenomenon that emits energy.
In other words, while all the matter that crosses a black hole’s event horizon falls in and be lost for ever, a white hole explosively ejects all the matter that was initially lost in the black hole.
This is purely a hypothetical concept, and there is no evidence for the existence of a white hole anywhere in the universe.
However, both structures possess the same features, mathematically and geometrically, because, they are theoretically just opposites of each other.
White holes are not something that it is possible to understand using physical intuition.
White holes pop up in general relativity (which also explains the expansion of the universe) and that theory as a whole is not easy to understand physically.
The only way most people can understand general relativity is through mathematics.
Hopefully that will give you some idea of why it is so hard to explain some of these concepts without resorting to mathematics.
This does not mean that we shouldn’t try, but it does mean that we might not succeed at the first try.
Many smart people try very hard to get ideas from General Relativity across without using the Mathematics which the theory is based on, but that is something that is very hard to do.
It probably requires a level of understanding of the theory which I would absolutely NOT claim to have.
So come to the point
A white hole is an object that emits matter and energy in a way that parallels a black hole sucking in matter and energy.
A white hole has never been observed. It is a possible solution of Einstein’s field equations but that doesn’t prove that it is possible, or even that an instance exists.
White holes appear to break the law of entropy, because they decrease it.
It has been argued that the Big Bang is actually a white hole, with everything ejected at once.
There is a fundamental problem with the Big Bang. We have no established theory of what caused it, so at this stage it might as well be a white hole as any other explanation.
Similarly, if black holes just suck stuff in where does it go and why hasn’t everything disappear into one big black hole if the universe has been around forever.
Obviously, there is some additional stuff going on that we have not come to grips with yet.
One idea is that the stuff that goes into black holes pops out of white holes or maybe a big bang in a separate piece of spacetime.
What would a white hole look like if it did exist
A white hole is pretty much like an ‘anti-black hole’. A black hole is a place where matter can be lost from the universe.
A white hole is a place where (if it could exist with any matter in it — which it can’t) matter would pop out into the universe.
This has many similarities to the Big Bang singularity (although it’s not quite the same, since there was nothing before the Big Bang).
Physicists have clear evidence that black holes exist, however, they don’t have any evidence that white holes exist and neither do they think white holes exist.
The Second Law of Thermodynamics says that the entropy of an isolated system does not decrease, however, the math shows that white holes actually decrease entropy.
Think of a black hole and white hole being connected so that if something goes in a black hole, it will come out of a white hole.
So, while going into the black hole, that object, say a mobile, would be sliced into a thin line of atoms, but, it would come out of the white hole as a mobile.
Obviously that isn’t possible, but, the universe is full of surprises so they’re may be a tiny chance white holes exist.
Also, white holes are thought to be time-reversed black holes.
Karl Schwarzschild’s solution of the Einstein Field Equations shows us that time and space switch roles inside a black hole.
Space flows inwards, towards the singularity of the black hole, making it unidirectional and time-like, while, time becomes space-like and can be traversed in any direction.
If you fall in and somehow survive, below you will be the “past” of the black hole, everything that has fallen in the hole before you and the singularity (the collapsed star), and above you will be the “future” of the black hole, everything that has fallen after you.
However, since every part of your future light cone points towards the singularity, the singularity essentially becomes your future.
Now, if white holes are time-reversed black holes, it means that the singularity, rather than being a future event for an observer, is a past event.
👇👇👇
