spaceSpace and Physics

Could Wormholes Give Us The Long-Sought Theory Of Quantum Gravity?


Jonathan O'Callaghan

Senior Staff Writer


It’s Thursday. You’re tired, maybe hungover. The weekend is nearly here. But before all that, we’ve got some physics for you to sink your teeth into. We’re talking wormholes, black holes, and quantum mechanics.

Yes, there’s a new theory on the block, and this one is seeking to rectify one of the biggest problems in physics at the moment – linking Einstein’s theory of general relativity with quantum mechanics. It’s been devised in a paper by Leonard Susskind from Stanford University that is yet to be peer-reviewed, but a pre-print is available on arXiv.


Susskind proposes a new “equation” of sorts to reconcile general relativity and quantum mechanics: ER = EPR. The left-hand side of the equation refers to a 1935 paper from Einstein and Nathan Rosen on wormholes; the right is Einstein, Rosen, and Boris Podolsky’s paper of the same year on quantum entanglement.

This new paper from Susskind builds on an idea he first proposed with Juan Maldacena from the Institute for Advance Study at Princeton in 2013; both of these ideas are the same. Or, in other words, things like black holes can be linked together by wormholes.

Quantum entanglement, the bit denoted by EPR, is the strange behavior of particles where they can be linked and share a quantum state. This means that changing the quantum properties of one changes the other, even at great distances, something being tested by China with a new quantum communications satellite.

The other side of the equation, ER, talks about how two positions in the universe can in theory be linked by a wormhole; traveling through would transport you from one location to the other.


According to Susskind, though, it is not just particles that can be entangled. He suggests that things like black holes can also share properties at great distances, and they would be linked by some sort of quantum wormhole. “What all of this suggests to me, and what I want to suggest to you, is that quantum mechanics and gravity are far more tightly related than we (or at least I) had ever imagined,” he writes in his paper.

As Tom Siegfried explains in Science News, this is just one theory attempting to link quantum entanglement and gravity. And the emergence of these theories suggests we may be getting closer to resolving one of the outstanding questions of physics of our time, a unified theory of quantum gravity. “And Susskind believes that the path to quantum gravity – through the wormhole – demonstrates that the unity of the two theories is deeper than scientists suspected,” he notes.

Now, get back to your weekend preparations.


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