“Outside of a dog, a book is a man’s best friend. Inside of a dog, it’s too dark to read.” –Groucho Marx
“While no one has proved that wormholes exist, that does not for a moment keep the more adventurous of thinkers from trying to figure how they might behave.”
–Michael Lemonick, Time magazine
Wormholes. We’ve all heard the word before, and we’re used to the concept (thanks to science fiction) that wormholes could be tunnels to either completely different locations in space or in time!
How so? You see, when you get enough mass (or other form of energy) in a small enough space, it becomes harder and harder to escape from it, gravitationally. The Earth isn’t so bad; you “only” have to travel at about 25,000 miles-per-hour (~40,000 km/hr) to escape from its gravity, something we’ve been doing since the 1960s.
But if you keep turning up the mass, you’d need to travel faster and faster to escape. You can add mass to something arbitrarily, but as for velocity? There’s a limit to that: the speed of light. If you make something so massive that you can’t escape from it, even if you move at light-speed, congratulations! You’ve just made a black hole: something with gravity, but that emits no light; that anything can be sucked into, but that nothing can escape from!
Well, the “reverse” of a black hole would be something that nothing can be sucked into but that everything can escape from: a white hole.
White holes are not observed to exist, but they are theoretically possible. Something interesting? If you have a black hole in one region of space, it could, in principle, be connected on the other end (in a separate region) to a white hole! The connection between the two — the black hole and the white hole — is known as an Einstein-Rosen Bridge, or more popularly, a wormhole.
Some have speculated for a long time that when matter falls into a black hole, it emerges somewhere else as a white hole, and that this apparent “boom” of matter, seeming to come from nowhere, would look an awful lot like our Big Bang. In fact, some say, perhaps that’s where our Universe got its start! It’s an interesting idea that we have not been able to test (yet), but that is certainly a worthwhile speculation.
But recently, a paper has come out (and you can read the preprint here) that asks the question: could our Universe live in the “neck” of one of these wormholes?
Although this is making news on the net, I’m here to bring you back to reality. First off, this is not a new idea; it’s been around since at least 1972. Second of all, what the author finds is that the interior of an Einstein-Rosen black hole is static, which is not a property of our (expanding) Universe.
But this paper does show a few interesting things. First off, this solution is stable, which means — in principle — that it can exist. Second off, it is possible that this can be generalized to make the space inside of it do other things besides remain completely static (like expand or contract). And third off, it brings up this amazingly interesting possibility that not only might our Universe be the inside of a black hole, but that each black hole that’s come to exist in our Universe may house its own miniature Universe inside of it!
Is there any way to test this? Not yet, since a black hole like this would look identical from the outside to a plain old “I’m-a-singularity-at-the-center-and-nobody’s-going-nowhere” Schwarzschild black hole.
So in summary, I’m skeptical that this idea is right, and I’m even more skeptical that this idea is testable in principle. But that doesn’t mean it isn’t incredibly interesting in its own right, and that further research might bear out some awfully interesting details. I have a feeling we’ll be hearing about this one again sometime soon.