World Science: Signs of dark matter found?

[freyar]

I see, I see. Actually I know some of that stuff 'cause I studied it, albeit superficially, but it's the details that usually escape curious non-specialist, I guess.
Like, I never figured out why hypotheses have been made that "on the other side" of a black hole there might be an opposite reflex (something like a "white hole", I think I've read).
I mean, science-fictional parallel dimension out of holes in the time-space, ok, but, scientifically speaking, if all we know is that a black hole is an object of enourmous mass esercising enormous attraction, why should it even have "another side"?
Or maybe I just misinterpreted something, or even just read fluff out of bad articles?

Umbran got in there with some nice comments, too...

Atanatotatos, the "white hole" thing comes about if you try to describe a black hole that has existed forever. It just sort of appears in the mathematical description. However, they aren't there in the mathematical description of a black hole that forms from the gravitational collapse of, for example, a star. I do think that some authors have gotten carried away when talking about "white holes" (and, shoot, they make cool sci-fi ).

 

[Umbran]

However, they aren't there in the mathematical description of a black hole that forms from the gravitational collapse of, for example, a star.

I think something similar also comes out of the descriptions of spinning, charged black holes. If you enter the event horizon, you can dodge the singularity and come out in what is, in effect, a separate spacetime.

That is, if you don't get spaghettied by the tides near the singularity first. I think it may only be possible in a super-massive black hole, where there's a greater span of survivable gravity gradient between the event horizon and the singularity.

 

[Atanatotatos]

I think something similar also comes out of the descriptions of spinning, charged black holes. If you enter the event horizon, you can dodge the singularity and come out in what is, in effect, a separate spacetime.

I'm sorry, but now I don't think I get what you mean...

 

[Umbran]

I'm sorry, but now I don't think I get what you mean...

It is an extreme case in relativity.

At the very center of the black hole is a "singularity" - the point at which the normal laws of physics cease to apply.

Some distance out from the singularity is the "event horizon" - this is the black surface of the black hole. Outside that surface, light can escape out to the rest of the universe. Inside the surface, nothing, including light, can escape. Anything that falls inside the Event horizon is doomed to eventually fall down to the Singularity.

That is, unless the black hole bears a large electrical charge, and spin. In that case, it is possible to trace a line down towards the singularity, that then bends away to escape. However, if an object takes this path, the event horizon still lies between the object and it's original universe. The interpretation of this is that it escapes into another spacetime - basically, it has skipped off into another reality.

Nobody has ever seen this, of course - if it has ever happened, we are incapable of ever seeing it, as the information that it has happened cannot be transmitted back across the event horizon.

 

[Atanatotatos]

I...see. More or less. I guess it's one of those interpretation only a physic can hold as real, though. (not that it doesn't hold a reality.)