While no one knows for sure what would happen if you fell into a black hole, it's probably safe to say that you wouldn't be back this way again.
By most scientific reckonings, the incomprehensible force exerted by a black hole squishes anything that falls under its sway — no matter how massive — into a single point in the universe known as a singularity.
Now, try to imagine another possibility, that instead of being a final destination for all things, a black hole is actually a doorway. Or better yet, a hub in an intergalactic transportation network, otherwise known as a wormhole.
Sound a little far-fetched? Sure, it does. But then again, we're already talking about a star-eating chasm that bends time and light. While the mind is already thoroughly boggled, why not slip another theory in there?
That's exactly what physicists from the University of Buffalo and China's Yangzhou University aim to do with research published in the journal Physical Review D.
The scientists suggest there's a slim chance that a black hole could be so much more than a dead end, but rather a passage through space and time — a way to traverse vast amounts of physical space in an instant.
That would be a wormhole, an entirely theoretical shortcut in spacetime that links two disparate locations in the universe.
And it would be quite a turnaround on traditional black hole theory that suggests everything entering a black hole, including your hopes and dreams, is lost forever. But is it even remotely possible?
The most conclusive way to find out would be to send something through one of these all-consuming hoovers. But it would take thousands of years for any probe to reach our nearest galactic carnivore.
Instead, the research team focused on a certain canary that's been hanging around the coal mine known as Sagittarius (Sag) A*. That's the black hole thought to preside over the center of our own Milky Way galaxy. And the "canary" would be a star called S2 that's been dawdling recklessly around the supermassive black hole's mouth for millennia.
If indeed Sag A* is a wormhole, we might expect there to be stars like S2 loitering around the other end of the tunnel. Although another star might be physically located in a far off space, the wormhole would bridge the gap, making it much closer. In fact, that other star could be close enough to S2 that it exerts a gravitational influence through the potential wormhole.
"If you have two stars, one on each side of the wormhole, the star on our side should feel the gravitational influence of the star that's on the other side," Dejan Stojkovic, a professor of physics at the University at Buffalo, explains in a news release. "The gravitational flux will go through the wormhole."
"So if you map the expected orbit of a star around Sagittarius A*, you should see deviations from that orbit if there is a wormhole there with a star on the other side."
So how would you know?
In their new research, the physicists don't yet offer an answer, but they devise a new technique for distinguishing wormholes from their black-hearted brethren. Stare at the star on our side of the black hole long enough — likely for several decades — and its telltale wobble will suggest something on the other side of the chasm is pulling its gravitational strings.
Of course, since theoretical wormholes are even weirder than theoretical black holes, it's not that simple. For one thing, we don't yet have the equipment for such a sensitive observation at that kind of distance. And for another, the result still wouldn't be conclusive. If S2 doesn't show any sign of a wobble, that could just mean there's no star at the other end of the tunnel.
"When we reach the precision needed in our observations, we may be able to say that a wormhole is the most likely explanation if we detect perturbations in the orbit of S2," Stojkovic notes in the release. "But we cannot say that, 'Yes, this is definitely a wormhole.'"
But at least Albert Einstein gives the concept some credence.
According to his more-than-a-century-old theory of general relativity, a wormhole could exist, at least mathematically.
Everyone at least agrees that if wormholes were real, they wouldn't help faraway aliens get their Amazon packages any faster.
Spacecraft, much less people, wouldn't be able to squeeze through the wormhole's mouth. Opening the mouth of a wormhole, at least in theory, requires an impossible amount of energy. And if it could be opened, those jaws would clamp down again almost instantly, according to a 1935 amendment to Einstein's ideas called the Einstein-Rosen theory.
In that regard, the wormhole researchers are inclined to agree.
"Even if a wormhole is traversable, people and spaceships most likely aren't going to be passing through," Stojkovic notes. "Realistically, you would need a source of negative energy to keep the wormhole open, and we don't know how to do that. To create a huge wormhole that's stable, you need some magic."
Then again, who's to say more advanced civilizations in the universe haven't already managed to pry open a wormhole — and turned Sag A* into one of the busiest superhighways in the cosmos?
At the very least, the researchers have conjured a little magic of their own. They cast a ray of hope on a place that famously eats rays for breakfast.