I What Makes Black Holes Black and White Holes White?

[petrushkagoogol]

What makes black holes "black" and white holes "white" ?

 

[Drakkith]

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".

 

[newjerseyrunner]

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.

 

[Chronos]

We cannot be certain either entity actually exists, but, we have solid evidence for black holes and virtually zero evidence favoring white holes.

 

[Mary Space]

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.

 

[newjerseyrunner]

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.

 

[Chronos]

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.

 

[Mary Space]

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."

 

[Chronos]

Not unheard of for wiki to spout unsupported bs such as this.

 

[Mary Space]

Not unheard of for wiki to spout unsupported bs such as this

I just translated this quote from russian on english.
If you want I can give you a link on original's language and if you understand russian you can read this.
https://ru.wikipedia.org/wiki/Белая_дыра

 

[newjerseyrunner]

"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.

 

[Mary Space]

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

 

[Sue Rich]

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.

 

[rootone]

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.

 

[Garett Kutcher]

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?

 

[rootone]

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.

 

[phinds]

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.

 

[praveena]

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 black hole is finite?Is that singularity is the end??

 

[rootone]

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.

 

[praveena]

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 black hole is finite?

 

[rootone]

... without knowing the end how we can conclude black hole 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.

 

[newjerseyrunner]

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.

 

[Chronos]

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.

 

[hsdrop]

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

 

[Sue Rich]

How you are saying that black hole 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.

 

[Chronos]

A white hole is one possible solution to the Einstein field equations, as is a black hole. Mathematical possibilities, however, are not always realized in nature. We already have reason to believe GR is an incomplete description of gravity, and will remain so until we have a valid theory of quantum gravity - which is a possibility in the not so distant future. Once we unify quantum physics with GR many puzzles with things like black holes and white holes should be resolved. In the mean time we must rely on observational evidence to realize the distinction between reality and mathematical artifacts. The observational evidence favoring black holes as a valid solution to EFE is overwhelming. The evidence favoring white holes is virtually nonexistent. The prime directive in physics is a theory is nothing more than a hypothesis until until predictions made by that theory are confirmed by observational evidence.

 

[hsdrop]

ok i know white holes are only theory so far but i was wondering if time could work in a different in the way than black holes has shown to be... like only lasting for a nano sec spewing out energy and matter then somehow shut off or run out of energy and matter for the nano sec?? or are they predicted to hang around as long as the cosmic vacuum cleaners do?

 

[Fervent Freyja]

\ 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?.

The nearest black holes are thousands of light years away...

 

[Chronos]

Yet we observe phenomena in various parts of the universe that cannot be accounted for by any known physics aside from black holes. The same cannot be said for white holes.

 

[phinds]

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.

What good would sending a camera in do? It can't come out again, nor can any information from it so what would be the point?

Also, the nearest known BH is tens of thousands of light years away so would take us hundreds thousands of thousands of years to get there.

There are other problems.

I don't think your camera idea works out too well.

 

[Chronos]

Technically Cygnus X-1, one of the strongest black hole candidates, is a mere 6000 light years distant - re: http://www.nasa.gov/mission_pages/chandra/multimedia/cygnusx1.html. It would still be a protracted journey with current technology - about 130 million years. Talk about those annoying 'are we there yet's.

 

[Garett Kutcher]

Yet we observe phenomena in various parts of the universe that cannot be accounted for by any known physics aside from black holes. The same cannot be said for white holes.

I was reading this https://www.sciencenews.org/blog/context/new-einstein-equation-wormholes-quantum-gravity and was wondering what the difference between white holes and worm holes would be? Maybe we do see evidence for white holes, but don't realize it- of course, I am most likely wrong.

 

[Chronos]

The short answer is nothing exits a black hole and nothing enters a white hole.

 

[rollete]

You can't enclose anything infinite inside a finite volume.

Well, the 'depth' of a point is infinite.

The nearest black holes are thousands of light years away...

What good would sending a camera in do? It can't come out again, nor can any information from it so what would be the point?

Also, the nearest known BH is tens of thousands of light years away so would take us hundreds thousands of thousands of years to get there.

There are other problems.

I don't think your camera idea works out too well.

Party poopers with no sense of humor.

The short answer is nothing exits a black hole and nothing enters a white hole.

That depends. Are we talking about spacetime holes or humanoid holes?

I never heard of a 'white hole' beyond the biological realm before.

 

[phinds]

Party poopers with no sense of humor.

No, party poopers who poop on crackpot science

I never heard of a 'white hole' beyond the biological realm before.

I take it you know little about cosmology. It's an extraordinarily common term (in cosmology). Just for grins, I just Googled it. ALL of the two pages were referring to cosmological white holes and I'd be surprised if the next 10 were not as well. I think your sense that it is a biological term is a significantly minority view.

 

[phinds]

Well, the 'depth' of a point is infinite.

No, the depth of a point is zero.

 

[rollete]

The spatial precision of a point can be infinitely augmented (Planck length be damned). In other words, no limits to how small space can be parsed. That's 'depth' in a way, but one need not restrict the understanding of 'depth' to conventional tridimensional space.

Never argue with a layman!

 

[Drakkith]

The spatial precision of a point can be infinitely augmented (Planck length be damned). In other words, no limits to how small space can be parsed. That's 'depth' in a way, but one need not restrict the understanding of 'depth' to conventional tridimensional space.

Never argue with a layman!

One needs to restrict the usage of terms here at PF to the standard convention used in science and engineering, otherwise you cannot have a meaningful discussion without pages and pages of back and forth arguing over what some term means. That's not helpful when people are trying to learn mainstream science.

In standard science and math a single point has no dimension and cannot have 'depth'. Furthermore, the division of space into smaller and smaller sections has absolutely nothing to do with depth unless you shoehorn some abstract meaning into it. Please don't do that.

 

[Chronos]

There are good reasons to believe there is a limit to how small something can be and stiill be something - e.g., HUP.

 

[Fervent Freyja]

Party poopers with no sense of humor.

Get to it, then! Send a camera into a black hole for me. I will throw a party in your honor and gift you with whatever you wish.

 

[Khashishi]

A white hole is a time-reversed black hole. In classical kinematics and relativity, you can take any solution and time-reverse it and get another solution. But once you include thermodynamics, you see that most time-reversed solutions are not allowed. So, there's no reason to believe white holes exist.

 

[hsdrop]

ok that makes a lot more sense to me once you explain how the math and the numbers for it worked I didn't start the thread but thank you