Einstein’s theory of general relativity is the best way, as far as we know, to explain the universe. Its solutions have been tested against observations time and time again, and it continues to remain victorious. But it is also a complex theory that allows for solutions to exist that are nothing like what we see in our universe.
One of these solutions, known as Einstein-Rosen bridges, or more commonly wormholes, are a way to connect two separate points in space-time. Researcher Daniel Jafferis has now proposed a way in which these wormholes could potentially be stable and exist in our universe. There’s only one issue: they wouldn’t actually be shortcuts. He presented findings at the 2019 American Physical Society April Meeting in Denver.
“It takes longer to get through these wormholes than to go directly, so they are not very useful for space travel,” Jafferis, a Harvard University physicist, said in a statement. “The real importance of this work is in its relation to the black hole information problem and the connections between gravity and quantum mechanics.”
The traditional solution has wormholes, also known as eternal black holes, forming and then collapsing on themselves as they are intrinsically unstable. Ways to stabilize them involve the use of exotic matter that possesses negative energy. Given that no such thing has yet been found, they are regarded as “fun but improbable.”
Jafferis’ wormholes have a different setup. The two ends of a wormhole are black holes and they are entangled, meaning that they are in a single quantum state and changes to one black hole produce changes onto the other, even if they are separated by a long distance.
This specific setup allows for stable wormholes and light could travel through them, but it takes longer than if it was outside the system. This approach also has another important consequence. With it, it is possible to extract information from the black hole, something that has puzzled physicists for decades.
Quantum mechanics and relativity don’t work well together, and in black holes, this is illustrated clearly by the information paradox. The physical information pertaining to a particle falling in a black hole disappears once the particle crosses the event horizon. This is not allowed in quantum mechanics. There are a few solutions to this paradox, but many feel that only when we construct a theory that can encompass both relativity and quantum mechanics we’ll resolve it.
Jafferis' work posits itself in that path: Finding a way to incorporate gravity into the standard formulation of quantum mechanics.