"Black" holes and "White" holes

  • #1
What makes black holes "black" and white holes "white" ? :cool:
 
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  • #2
Drakkith
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Black holes absorb all radiation and matter that falls within the event horizon, and hence they are "black" (non-emitters). White holes emit radiation and matter from within, and thus are "white".
 
  • #3
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With a black hole, space is curved so much inwards that there is no path that leads anywhere but deeper into the hole. With a while hole, space is curved so much outwards that there is no path that leads anywhere but further away from it. White holes would require a negative energy density, and hence are thought to be physically impossible, just a mathematical curiosity.
 
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  • #4
Chronos
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We cannot be certain either entity actually exists, but, we have solid evidence for black holes and virtually zero evidence favoring white holes.
 
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  • #5
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Hello
"Black holes" so called because the light that goes through it has a lower speed than the gravitational force of black holes that's why light can't get out of it, and we can't see it, so these holes called "black."
About the "white hole", as I know, the scientists they have not yet found, but according to the law of conservation of energy, this energy that enters a black hole should get out of the white hole, and if the light is in a black hole can not escape, the white hole It acts with a repulsive force, and we see a bright light that's why "white holes" so called.
I hope I could help you.
 
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  • #6
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Hello
"Black holes" so called because the light that goes through it has a lower speed than the gravitational force of black holes that's why light can't get out of it, and we can't see it, so these holes called "black."
About the "white hole", as I know, the scientists they have not yet found, but according to the law of conservation of energy, this energy that enters a black hole should get out of the white hole, and if the light is in a black hole can not escape, the white hole It acts with a repulsive force, and we see a bright light that's why "white holes" so called.
I hope I could help you.
Not quite, it means that light speed is slower than the escape velocity caused by gravity. Gravity is also radiating at the speed of light.

Black holes and white holes are not related. Energy going into a black hole simply gets stuck there and then radiated away as Hawking radiation. Black holes are not wormholes to white holes, they are simply inescapable gravity pits.
 
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  • #7
Chronos
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Per GR gravity propogates at a speed of exactly c - the same as light. While we do not know what goes on inside the EH of a black hole, a wormhole appears unlikely. If light, or anything else, had a wormhole escape route, the black hole would lose mass equivalent to the escape rate. A white hole powered by a black hole would suck the black hole dry in short order. There is no evidence suggesting this happens.
 
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  • #8
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Poster has been reminded that wikipedia is not a valid scientific reference for making assertions
Not quite, it means that light speed is slower than the escape velocity caused by gravity. Gravity is also radiating at the speed of light
Yes, I had that in mind but incorrectly expressed

Black holes and white holes are not related. Energy going into a black hole simply gets stuck there and then radiated away as Hawking radiation. Black holes are not wormholes to white holes, they are simply inescapable gravity pits.
Some footnotes from Wikipedia
"Theoretically, it is assumed that white holes can be formed at the exit from the horizon of the black hole event substance which is in the opposite direction of the thermodynamic arrow of time. It should be understood that the full space-time map contains both black and white holes, and a separate entity only "pure" black or only "pure" white hole to complete the map of the space-time can not be in principle."
 
  • #9
Chronos
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Not unheard of for wiki to spout unsupported bs such as this.
 
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  • #11
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"Theoretically" probably means "mathematically theoretically." Sure, you can have a white hole if you can have negative energy density. We've seen no indication that such a thing is physically possible.
 
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  • #12
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yes white hole is the theory as well as Hawking radiation, think you will agree that in the universe are lot of theories and few facts, so it remains to wait for confirmation from scientists
 
  • #13
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If a black hole draws in everything within it's event horizon, and keeps drawing it deeper, does that mean the black hole is infinite? And what about white holes? Since they emit matter, could they be the other side of a black hole (assuming there is one)? I'm curious as to what kind of studies have been done on this subject.
 
  • #14
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No white hole has ever been observed. unsurprising since this would involve exotic matter having negative gravity.
Black holes, or at least the gravitational and other effects of black holes (eg quasars) have been observed.
It is indeed a conundrum that this implies infinities (a singularity) at the centre of a black hole.
We don't actually know what happens there, but the fact that the math leads to infinities is most likely an indication that whatever is going on is physics of which we currently have no idea.
 
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  • #15
Is there any evidence [what would such evidence even look like] that the creation of a black hole is the 'big bang' of an new universe or is that just a pretty science fiction idea?
 
  • #16
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Is there any evidence [what would such evidence even look like] that the creation of a black hole is the 'big bang' of an new universe or is that just a pretty science fiction idea?
The idea has been suggested before but as far as I know it's pure speculation.
 
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  • #17
phinds
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If a black hole draws in everything within it's event horizon, and keeps drawing it deeper, does that mean the black hole is infinite?
What makes you think it "keeps" drawing it deeper? It draws it to the center and that's it. Black holes are finite.
 
  • #18
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What makes you think it "keeps" drawing it deeper? It draws it to the center and that's it. Black holes are finite.
How you are saying that blackhole is finite?Is that singularity is the end??
 
  • #19
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The singularity is simply where the math breaks down and produces nonsense results.
It is NOT a description of a physical object.
We DON'T KNOW what physically is going on at the center of a back hole.
We do know that the infalling stuff is by this time no longer in the form of atoms, because atoms disintegrate before that point.
Neutron stars, (very massive objects which are not quite massive enough to be black holes), are known to exist by observation, and what we observe IS consistent with GR math.
The star has become mainly a soup of neutrons with other subatomic fragments mixed in.
 
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  • #20
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The singularity is simply where the math breaks down and produces nonsense results.
It is NOT a description of a physical object.
We DON'T KNOW what physically is going on at the center of a back hole.
We do know that the infalling stuff is by this time no longer in the form of atoms, because atoms disintegrate before that point.
Neutron stars, (very massive objects which are not quite massive enough to be black holes), are known to exist by observation, and what we observe IS consistent with GR math.
The star has become mainly a soup of neutrons with other subatomic fragments mixed in.
I know that.I am asking that without knowing the end how we can conclude blackhole is finite???
 
  • #21
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... without knowing the end how we can conclude blackhole is finite???
Well strictly speaking we can't make any conclusions at all since we can't observe anything, we can't reproduce the conditions, and the best theory we so far have; GR, doesn't make sensible predictions.
We do know that stuff (like us) exists externally to the black hole though, so in that sense it can't be infinite.
 
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  • #22
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We do know that stuff (like us) exists externally to the black hole though, so in that sense it can't be infinite.
This is an illogical statement. Complete and infinite do not mean the same thing. For example: a set of all positive integers is an infinite set, but does not contain all numbers.
 
  • #23
Chronos
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We know the mass of black holes is finite. It has been measured with great accuracy in cases such as Sag A. All you need for a black hole is to compress mass into a volume less than its Swarzschild radius - which is also finite. You can't enclose anything infinite inside a finite volume.
 
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  • #24
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i have a couple of question about the theory of white holes if no one mine me sounding a little slow but what is the explachen rate of a wight hole and would it be fast enough to affect gr and sr
 
  • #25
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How you are saying that blackhole is finite?Is that singularity is the end??
That's mostly the theories I've read about, Praveena. I wonder why no one has ever tried to send a camera of some sort inside a black hole to actually see what happens before (or if) it's destroyed? Until we actually know what's inside, everything we say is nothing more than conjecture or speculation at this point.
 

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