I Any evidence of white holes in the Universe?

[Slavik Komarova]

We have much evidence of the existence of black holes in our universe ... so why does not the same occur in relation to white holes since they are also the result of the same theoretical prediction ?

 

[phinds]

What research have you done to answer that question?

 

[Slavik Komarova]

lately I have researched the topic white holes and have not found an answer to some questions, among them the absence of evidence of these astrophysic objects

 

[phinds]

Do you think the absence of evidence is evidence of absence? Carl Sagan said that's not the case but perhaps in this case the absence of evidence really IS because they don't exist in the real world but are merely a mathematical construct.

EDIT: I see you've marked this thread as Advanced, so I assume you are familiar with Einstein's field equations, yes?

 

[Orodruin]

Simple. White holes are not predicted by theory. That a white hole solution to Einstein’s field equations exists does not mean it needs to be realized in our universe.

 

[PeroK]

lately I have researched the topic white holes and have not found an answer to some questions, among them the absence of evidence of these astrophysic objects

The black holes in our universe result from the collapse of a sufficiently large star. There is no astrophysical process that would result in a white hole.

 

[Vanadium 50]

And, at the risk of piling on, if there were a white hole in some distant galaxy, how would you tell?

 

[andrew s 1905]

And, at the risk of piling on, if there were a white hole in some distant galaxy, how would you tell?

Well I imagine you would calculate the expected spectrum (thermal ?) and compare it with observation. You would look to eliminate other possibilities like black hole accreation disks massive stars etc.

One could of course have made such disparaging remarks about black holes in my life time.

Regards Andrew

 

[Vanadium 50]

Well I imagine you would calculate the expected spectrum (thermal ?)

Picking a glaxy at random, M81 for example has a quarter of a trillion thermal sources (stars), How do you tell which one is actually a white hole?

One could of course have made such disparaging remarks about black holes

First, the word for "how are you going to tell observationally/experimentally?" is not disparagement. It is science.

Second, the observational evidence for BH's was laid out in advance -accretion disks, nearby star orbits, interferometric imaging, GWs, etc.

 

[andrew s 1905]

Picking a glaxy at random, M81 for example has a quarter of a trillion thermal sources (stars), How do you tell which one is actually a white hole?

The same could have be said of black holes.

Second, the observational evidence for BH's was laid out in advance -accretion disks, nearby star orbits, interferometric imaging, GWs, etc.

In advance of what? Certainly, not the discussion of if they existed or not. You are reflecting the polished hindsight view of the reality of the the road to the acceptance of the reality of black holes and that they had been observed conclusively.

The disparagement was was in the "risk of piling on". The same question was posed about black holes it was not all laid out in advance as you stated.

Regards Andrew

 

[andrew s 1905]

On reflection the big difference between black and white holes was that there was/is a theoretical way to created a black hole from what had already been observed or near extrapolation while none exists (as far as I know) for white holes.

Regards Andrew

 

[PeterDonis]

why does not the same occur in relation to white holes since they are also the result of the same theoretical prediction ?

No, they aren't. To expand on previous comments, the theoretical prediction that we should observe black holes in our universe is based on (a) models of gravitational collapse to black holes, starting with the 1939 Oppenheimer-Snyder 1939 paper, and (b) theoretical work on the possible states of matter, starting with the work of Harrison, Wakano, and Wheeler in the 1950s, which showed that all non-black-hole states of matter that are supported by degeneracy pressure have a maximum mass limit, so that objects over the limit must collapse to black holes.

The above work does not predict that white holes should be observed.

 

[PeterDonis]

I imagine you would calculate the expected spectrum

You can't do this for a white hole, because a white hole is inherently unpredictable: the initial singularity inside the hole could produce anything (or, what comes to the same thing, you could say it does not provide a valid set of initial conditions at all to ground any predictions at all). That is why your comparison with black holes along these lines is not really valid: you can make predictions about what kind of spectrum black holes should produce under various conditions (making reasonable assumptions about its mass, spin, and what kind of matter is falling into it).

On reflection the big difference between black and white holes was that there was/is a theoretical way to created a black hole from what had already been observed or near extrapolation while none exists (as far as I know) for white holes.

Yes, this is correct.

 

[PeterDonis]

the observational evidence for BH's was laid out in advance -accretion disks, nearby star orbits, interferometric imaging, GWs, etc.

I'm not sure the historical development of BH theory and observation is quite that clean; Kip Thorne's Black Holes and Time Warps gives a good overview, in which various theoretical and observational lines proceeded in a rather jumbled fashion until the "golden age" of the 1960s when things started to be tied together into a unified picture. By the time projects like LIGO were under discussion, of course, the unified picture had been in place for some time and was indeed being used to drive various observational efforts.

In any case, it is true that observational predictions about BHs can be laid out in advance, whereas for white holes they can't; it's theoretically impossible, for the reason I gave in post #13.

 

[swampwiz]

You can't do this for a white hole, because a white hole is inherently unpredictable: the initial singularity inside the hole could produce anything (or, what comes to the same thing, you could say it does not provide a valid set of initial conditions at all to ground any predictions at all). That is why your comparison with black holes along these lines is not really valid: you can make predictions about what kind of spectrum black holes should produce under various conditions (making reasonable assumptions about its mass, spin, and what kind of matter is falling into it).Yes, this is correct.

This is probably a weak analogy, but is it akin in conception to multiplying by zero as opposed to dividing by it?

 

[PeterDonis]

This is probably a weak analogy, but is it akin in conception to multiplying by zero as opposed to dividing by it?

Not really, that I can see. Dividing by zero is a mathematically forbidden/inconsistent operation. A white hole is not a mathematically forbidden or inconsistent solution; the issues with it are issues of physical possibility or reasonableness, not mathematical consistency.