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Science fiction / science fact

Another AKICOLJ question:

What's the story with black holes, white holes, wormholes and all that? You get them in SF all the time. What I want to know is what science actually _knows_ about all three and how much is known, how much is theory and how much is wild theory not generally accepted by mainstream cosmologists.

Comments

( 9 comments — Leave a comment )
lil_shepherd
Jul. 15th, 2010 07:18 pm (UTC)
Good heavens!

I have no idea what science actually knows about White Holes and wormholes, though I suspect they are still only theoretical. However, Black Holes, as I understand it, have been detected, not only in this Galaxy, but in others.

"There's a hole, there's a hole, there's a hole in the middle of it all!"

I do remember that there is a lot of argument about whether there are singularities at the bottom of Black Holes or not, but that's a mathematical argument I am not qualified to follow.

NB: Is purplecthulhu on your flist? If not, do you want me to point him at this post. He's an astrophysicist and an SF writer.

Edited at 2010-07-15 07:20 pm (UTC)
philmophlegm
Jul. 15th, 2010 07:28 pm (UTC)
He isn't - feel free to send him this way. I'm also hoping for something from foradan...
wellinghall
Jul. 15th, 2010 07:37 pm (UTC)
Well I was going to say something, but I'll let the professionals deal with it!
philmophlegm
Jul. 15th, 2010 07:49 pm (UTC)
Ooh, I'd hate for anyone to be intimidated by the prospect of correction by a pro! Why not tell me your thoughts and if the astrophysicists agree with you, you'll look really clever...
wellinghall
Jul. 15th, 2010 08:15 pm (UTC)
Hmm ...

AIUI, based on reading some old sf and some older science fact -

There is quite a lot of theory out there. Some of the older theory is more-or-less well established. However, "older" is a relative term in black hole studies, and it is not uncommon for even fairly well-established theory to be overturned (or, at least, argued against) by newer theory. (There's an essay, by I think Niven - or possibly Pournelle - called "Fuzzy Black Holes Have No Hair" - which mentions this effect).

Much of the basic physics is well established. If you pack enough mass into a small enough space, it will be dense enough that even light cannot escape - that is the (or at least, a) definition of a black hole. And similarly (though less easily explainable) for other "basic" ideas about a black hole.

Black holes themselves are widely (universally? dunno) accepted by cosmologists, and might have been demonstrated to exist. But many of the more outre / detailed theories about them are just that. It is rather tricky to investigate black holes in the laboratory - and, the universe being a Big Thing, and mostly being empty space, also rather tricky to investigate them in real life.
lil_shepherd
Jul. 15th, 2010 08:14 pm (UTC)
Message from purplecthulhu

Black Holes, Wormholes and White Holes are all possible solutions to the equations of general relativity, and as such are accepted as theoretical possibilities.

Black holes have almost certainly been detected, ones that are the mass a few times that of the sun and others that are millions of times bigger in the centre of galaxies. There's one in the centre of our own galaxy - see eg. http://www.mpe.mpg.de/ir/GC/index.php

White holes, while theoretical possibilities, as far as we know would not be stable and have never been seen. They, like wormholes, would require impossible materials with negative mass to keep open.

Wormholes also have never been seen but, on a submicroscopic scale, might solve some problems in theoretical physics to do with the vacuum, but there are other possibilities.

So, to summarize, we're pretty certain black holes exist, they're fully accepted. White holes and wormholes all are accepted at some level but don't seem to have any role in the macroscopic universe.
philmophlegm
Jul. 15th, 2010 09:25 pm (UTC)
Great answer - pass on my thanks.

Actually, sod that, I'll send the thanks myself.
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( 9 comments — Leave a comment )