One of the biggest and most vexing problems in physics is how quantum dynamics and gravity relate to one another. But now, physicists may have uncovered an interesting crossover between general relativity and the quantum world, potentially providing a hint as to how general relativity can be reconciled with quantum dynamics, a pairing that, in the mathematical sense, is like trying to mix water and oil.
Wormholes are hypothetical “gateways” between two points in space and time. A consequence of the equations arising from Albert Einstein’s bedrock theory of General Relativity, wormholes have spawned countless science fiction dreams of time travel and zooming between two distant locations faster than the speed of light.
Although the physics of actually using a wormhole to traverse spacetime is highly debatable — at best, huge quantities of an as-yet unfathomable “exotic energy” would be needed to keep a “traversable wormhole” open — there are few physicists who would doubt their existence, regardless of whether or not we may ever actually observe their effects.
In the quantum world, an apparently disparate place when compared with general relativity (which governs gravitational interactions and, by extension, wormholes), “entanglement” between subatomic particles is possible. If one can “entangle” two particles, no matter how far apart they are separated, should any quantum changes occur to one entangled pair, that change will be experienced instantaneously by its entangled partner. Quantum changes can be communicated between entangled particles no matter how far they are separated — whether the distance be the width of a laboratory desk or if one entangled particle were magically transported to another galaxy — the quantum change is communicated instantaneously.
This strange quality of entangled particles could be used for, say, faster than light communications between two points or super-fast quantum computers where calculations are theoretically instantaneous.
Entanglement was abhorred by Einstein, who referred to the mechanism as “spooky action at a distance.” But in new calculations, researchers have found some potential common ground between wormholes and this spooky action between particles.
In a paper published last month in the journal Physical Review Letters, physicists from the University of Washington and Stony Brook University in New York point out that if one could entangle two black holes that were then pulled apart, a wormhole connecting the two black holes would be created and governed by an identical set of entanglement rules.
Black holes are known to exist at masses close to that of our sun to many billions of solar masses in the centers of galaxies. But microscopic black holes are also possible, in theory, so you wouldn’t need to worry too much about being sucked into a massive black hole to create an entangled pair of them — just pop out two black holes the size of atoms, entangle them and separate. The wormhole will form between the two. (At this point, if you’re scratching your head wondering how in the heck you’d accomplish such a feat, fear not, this is all theory. And in physics, it’s OK to imagine futuristic sci-fi technologies to make your theory jive.)
Sadly, the connecting wormhole could not be used for communication, at least not in the traditional sense. The only way to communicate with a buddy at the other end of the wormhole is “if you jump into your black hole, then the other person must jump into his black hole, and the interior world would be the same,” said physicist Andreas Karch, of the University of Washington.
But using two black holes and a wormhole as a superluminal telegraph system isn’t the point of this exercise.
The key thing to come out of these calculations is that the black holes, regardless of their size, will remain entangled, just like the entangled particles of the quantum world. In this case, any change to one black hole will be communicated instantaneously to the other black hole through the wormhole. Therefore, the wormhole, a construct born from general relativity, is acting in a very quantum manner.
The upshot is that “two different mathematical machineries” have been used “to go after the same physical process,” said Karch.
These calculations, though not practical, could help further research into quantum entanglement to see how it can relate to other, seemingly disparate systems.
Source: University of Washington
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