I’ve never seen a reasonable explanation of how this could possibly work–it seems to be more of a gimmick that hack sci-fi writers (as opposed to good ones) employ b/c they think it’s cool. Hence, I was disturbed to see the concept of black holes as a gateway to other parts of the universe used in the new Hayden Planetarium’s (American Museum of Natural History, NYC) Space Show.
Is there any reason to believe that traveling beyond a black hole’s event horizon would get you anywhere except dead and compressed into an infinitely small point?
Dead and smushed to a point is pretty much what you could expect and I think what most reputable scientists would go with.
Of course, space gets funky in a place where it wraps back in on itself and gravity is so powerful not even light can escape. If anywhere in the universe can be weird enough to poke into other universes or other parts of our universe then I’d say a black hole is a good place to start looking.
Of course, no one we ever sent in would be able to come back and tell us what coolness lies on the other side either (assuming they weren’t simply squished out of existence).
I’ve actually read a book claiming to be a proposal for human exploration of the universe by creating a black hole nearby. (first, build a bunch of ships to collect free-floating hydrogen)
There were a lot of complex graphs and math, and I really couldn’t tell you if it had any accurate basis. It seemed like it required entering a spinning black hole sideways?
That being said, the main reason I’m responding is a question about the whole singularity business. I’ve read a recent dumbed-down-for-us-laymen New Scientist article which stated physicists didn’t like the infinities at the center of black holes, and were searching around for theories to explain these fringes of Einsteinian physics.
True?
the theory about travel via a black hole depends on white holes being real. a white hole would bee the other end of a black hole. all matter sucked into a black hole would be spitted out the corrosponding white hole. I don’t think any scientist actually think a white hole exists.
also I don’t believe matter is actually compressed to a single point, no way to prove it - unless we can calculate the mass of a neutron star and find that it actually has a black hole in the middle but the star’s matter is beyond the border of the black hole
A lot depends on the shape of the universe. If, for example, the universe is saddle shaped one could imagine that if a black hole occured on the bottom of one ‘side’ of the saddle, it might well push it’s way through to the other ‘side’. Regardless, I agree w/ k2dave that it would require the existence of white holes. But maybe not…
Right, we can create wormholes but we need to find stuff with negative mass. It seems a little scarce around these parts…I seem to recall (perhaps it was in The Physics of Star Trek) that keeping a 10m wormhole open would require the energy output of all the suns in our galaxy. Anyway, all these wormholes and space warps require googolplexic amounts of energy and exotic matter.
There probably are wormholes, and there may even (possibly) be usable wormholes. However, they are not black hole/white hole pairs. The problem is basically that, were there white holes anywhere within several gigaparsecs, we’d see them… And we don’t. On the other hand, there’s plenty of black holes in that same radius. Where do they all empty out?
As to what’s inside a black hole, a point mass or whatever, all we can say is that the mass is spherically symmetric. Beyond that, all bets are off.
I’ve seen speculation that quasars might be white holes.
Of course, the most common explanation for quasars is that they are the massive amounts of energy released by matter spiraling into a supermassive black hole.
This link: http://web.ukonline.co.uk/ad.johnson/astrnmy/bh/blakhole.htm
, like others on the subject, seems to suggest these speculative warping effects would occur in a spinning Kerr type black hole. So if white holes exist, they may be very rare…
Well, almost all black holes are believed to be rotating to some degree, since the things they form from are generally rotating. Hawking radiation will tend to act in such a way as to reduce the rotation, but Hawking radiation is a very slow process.
As to the definition of a white hole, it’s something that repells so strongly, that not even light can get in :rolleyes:. The only reason to even consider them in real physics is as a long-shot potential answer to the question “What happens to the stuff that falls down a black hole?”. For these purposes, they don’t work, and there’s not really any explanation of how they would work, so toss 'em.
What I once read was that they are the mathematical opposite of a black hole, i.e. everything a blackhole does, a white hole does the opposite. I think it’s something that on paper is allowed, but most likely not in nature. The line that comes to mind is that they are unlikely, as since they are opposites, creating a white hole would be on the level of difficulty of destroying a black hole. So there ya go.
The probable reason you don’t see white holes is that mathmatically that should not exist.
Without a lot of quantum gymnastics, take darkcool’s dubious example. As mass accumulated in his black hole, it would start working its way to the other side. When it got about halfway, its mass would start distorting space on the other side. Sucking the space in towards it, so to speak,attracting matter thus creating another black-hole-in-the-making opposit the original.
When the two eventually meet, gravity cancels out their respective effects. So rather than a white hole spewing out great quantities of matter, the resulting ‘worm hole’ would become a fairly stable bridge in space itself until 1. the contained matter eventually ‘leakes’ back into space at large and the bridge closes ( in the case of small BH brides or 2. if the bridge is ‘wide’ enough ( in the case of large BH bridges) it will remain stable unless another black hole were to form within it, of course, causing it to collapse.
I have always wondered what would happen to matter in the bridge if both ends of the wormhole were closed at the same time. Would it be sucked outside our universe?? Would it be destroyed, isn’t this against the conservation of energy?
Also a black hole couldn’t possibly have an infinite density because it’s inertia would be infinite and couldn’t be moved by another mass (another star perhaps) and the gravitational potential energy would be destroyed once the star entered the huge gravity well.
Also do gravity waves interact with each other or with large or dense masses such as black holes? Or do they act like electro-magnetic waves and pass right through each other?? Does light cause a gravity wave?? What causes light surface-pressure if light has no mass??? Could this be caused by the gravity waves caused by the light?
If a wormhole closes, you’re left with a black hole. Note that of the wormholes believed toexist, you couldn’t even get the mass into it in the first place, without it collapsing, so it’s probably moot.
Gravity waves do interact, but only very weakly, since gravity is such a weak force. Large masses will affect both gravity waves and light waves, and in the same manner. Light could, conceivably, produce gravity waves, if you had a heck of a lot of it, but not to any significant degree. Light does not have rest mass, but it does have a mass equivalent to its energy and a momentum, so it can exert pressure.
Inertia is proportionate to mass, not to density, and black holes definitely have finite mass, so they’re OK.
Closing a ‘worm hole’ is not like laying a board across a hole. They are caused by space distortion, so to ‘close’ one would require un-distorting space and by definition bringing the matter inside of the worm hole out.
To echo Chronos, black holes do have finite mass.
Go to Kyberneticist’s link, and take a look at the figures, in particular the second figure in the section SpaceTime Diagrams, and the second figure in the next section, Spinning Black Holes. I remember seeing these figure in a book someone was reading in High School, and not uderstanding them then.
Now, twenty years and a bunch of college physics classes later, I ought to be able to figure them out. So I look them over, and they look like pseudo-physics babble to me. Do they look like that to anyone else who feels they ought to be able to understand them? Note: I don’t have a problem with space-time diagrams, just the description of black holes these are purporting to show.
