Few of you must have a fair idea about the warp drive and whether it might one day be feasible. Let’s discuss another faster-than-light trick: wormholes.
Wormholes are an old concept in general relativity. It’s based on work by Albert Einstein and Nathan Rosen, who attempted to figure out how elementary particles could’ve behaved in curved spacetime. Their concept treated particle-antiparticle pairs as two ends of a spacetime tube.
This Einstein-Rosen Bridge would resemble a black hole on one end, and an anti-black hole, or white hole, on the other end.
The particle physics concept never panned out. However, work inspired other researchers to analyze ER-bridges as a probable shortcut through space. If wormholes were traversable, you could excavate through spacetime like a worm drilling a hole through an apple.
It didn’t consume much time for theorists to realize this wouldn’t work. Although wormholes are valid solutions to Einstein’s equations, they crumble so fast, you’d never get time to go through them. In general relativity, wormholes aren’t traversable.
Impossibility never prevents a persistent theoretician and soon they found out you could make a wormhole traversable by lining it with some type of negative energy. The same type of negative energy could be employed for warp drive. However, matter with negative mass/energy doesn’t appear to exist.
But we can’t lose hope. We are aware that Einstein’s theory must break down at quantum scales as it is a classical theory. Probably, there is some quantum theory of gravity that displaces general relativity.
We don’t yet have an entire quantum gravity model, but we do have many approximate models that will take us in the right direction.
One of these models, known as the Einstein-Dirac-Maxwell theory is so named as it includes aspects of Einstein’s theory of gravity, Maxwell’s theory of electromagnetism, and Dirac’s theory of quantum particles. Recently a team discovered a wormhole solution to the Einstein-Dirac-Maxwell equations.
The team observed that their wormhole solution was fully traversable. What’s more, the solution doesn’t need any negative-energy states. In principle, that would let you travel through the wormhole without requiring negative mass.
The only catch is that you would have to be in a quantum state. That’s why microscopic clumps of atoms could travel through this wormhole, but not people.
Though this is interesting work, it is just a toy model. There are many solutions to Einstein’s equations that can’t exist for reasons beyond gravity. The team plans to explore their idea further to check if their solution is yet another impossible idea, or whether there could be a method to create this kind of quantum wormhole.
If this idea does work, it will still be convenient to pass through the eye of a needle than it will be to enter the distant heavens.