Wormholes are a fascinating concept in physics that postulate passages that connect two different points in spacetime — typically black holes — together.
Think “Interstellar” or “Event Horizon.” These wormholes could allow a person to jump into one black hole and emerge in a totally different galaxy, in a totally different part of the universe.
Unfortunately, most leading hypotheses surrounding wormholes suggest that they would collapse as soon as they formed due to instability. However, one new theory slated to be published in The Journal of Modern Physics D posits that, actually, wormholes can remain stable enough for objects to enter on one side and leave through the other.
Wormhole Metrics
The theory, by Ecole Normale Supérieure de Lyon computer scientist Pascal Koiran, relies on the Eddington-Finkelstein metric to describe the movements of objects in and around a wormhole. This metric differs from the more often used Schwarzschild metric, which breaks down once an object reaches the event horizon, meaning the point at which no object can escape the pull of a black hole, according to LiveScience‘s writeup of Koiran’s work.
Using the Eddington-Finkelstein metric, though, Koiran was able to mathematically simulate a path for an object into a black hole and through a wormhole instead of breaking down at the event horizon.
Of course, this doesn’t necessarily mean that jumping through any ol’ black hole will send you across the universe. However, it does pose a very interesting theory that shows that wormholes wouldn’t just instantly collapse as soon as they’re created.
We probably wouldn’t risk it, though, and would just wait on some startup to create a warp drive.
A narrow path
Once a theoretical wormhole exists, it's perfectly reasonable to ask what would happen if someone actually tried to walk through it. That's where the machinery of general relativity comes in: Given this (very interesting) situation, how do particles behave? The standard answer is that wormholes are nasty. White holes themselves are unstable (and likely don't even exist), and the extreme forces within the wormhole force the wormhole itself to stretch out and snap like a rubber band the moment it forms. And if you try to send something down it? Well, good luck.
But Einstein and Rosen constructed their wormhole with the usual Schwarzschild metric, and most analyses of wormholes use that same metric. So physicist Pascal Koiran at Ecole Normale Supérieure de Lyon in France tried something else: using the Eddington-Finkelstein metric instead. His paper, described in October in the preprint database arXiv, is scheduled to be published in a forthcoming issue of the Journal of Modern Physics D.
Koiran found that by using the Eddington-Finkelstein metric, he could more easily trace the path of a particle through a hypothetical wormhole. He found that the particle can cross the event horizon, enter the wormhole tunnel and escape through the other side, all in a finite amount of time. The Eddington-Finkelstein metric didn't misbehave at any point in that trajectory.
Does this mean that Einstein-Rosen bridges are stable? Not quite. General relativity only tells us about the behavior of gravity, and not the other forces of nature. Thermodynamics, which is the theory of how heat and energy act, for example, tells us that white holes are unstable. And if physicists tried to manufacture a black hole-white hole combination in the real universe using real materials, other math suggests the energy densities would break everything apart.
However, Koiran's result is still interesting because it points out that wormholes aren't quite as catastrophic as they first appeared, and that there may be stable paths through wormhole tunnels, perfectly allowed by general relativity.
If only they could get us to grandma's faster.
READ MORE: Wild New Theory Suggests Wormholes Could Be Stable Shortcuts Through Space-Time [LiveScience]