Theoretical physicists Leonard Susskind of Stanford University and Juan Maldacena of the Institute for Advanced Study put forth the proposal in a 2013 paper that wormholes and entanglement describe the same thing.
Entanglement refers to the entanglement of distance objects whose actions affect each other, despite lacking a physical link. Einstein called this “spooky action at a distance.” He collaborated with Nathan Rosen and Boris Podolsky in a separate 1935 paper that argued the rules of quantum physics allow for direct correlations between distance objects.
In a recent article for Scientific American, Maldacena describes his collaborative proposal with Susskind that these two separate theories are different ways to describe the same phenomenon, which if the equivalence can be proven could provide clues for developing a “quantum description of spacetime,” or theory of everything.
“The quest for a quantum gravity is one of the greatest unsolved problems in all of science. It has defied solution for the past 80 years,” said Dr. Michio Kaku in a phone interview with the Observer. Kaku is a professor of physics at City College of New York (CUNY), where he holds the Henry Semat Chair and Professorship in theoretical physics. “If we do get a quantum theory of spacetime,” said Kaku, “it should answer some of the deepest philosophical questions that we have like what happened before the big bang? Why did it bang? Why did it bang the way that it did? Is time travel possible? Can time go backwards? All these questions cannot be answered using just Einstein’s theory. Einstein’s theory breaks down at the instant of the big bang, or the instant you enter a time machine. So a quantum theory of everything should be able to answer some of the deepest philosophical questions about our universe.”
Kaku noted he often gets proposals in the mail claiming the sender has solved the missing pieces of Einstein’s equations, but with a quick glance the mistakes are easy to point out. “However, this proposal is being made by two heavyweights in theoretical physicists, so you have to take this seriously,” he added. “However, I also have questions. You see wormholes are very messy objects to work with. Most of the time they are unstable. Many physicists believe quantum corrections will close the wormhole, making them unstable, so claiming the equivalence of entanglement and wormholes is tricky.”
A genuine theory of everything, Kaku explains, could be used to calculate quantum corrections to wormholes, calculate their stability, and prove the equivalence of the two, but Susskind and Maldacena are working backwards to get to the theory of everything.
“Going backwards, I have my doubts,” Kaku said. “What they’re claiming is that if you can show the equivalence of these, two then it would give you a theory of everything. I’m not convinced about that because of course we still need to have a theory of everything that will allow you to calculate quantum corrections and the stability question of wormholes. So in summary, they could be right, this proposal has to be taken seriously. However, that said we have to realize wormholes are very difficult to work with. Quantum corrections could show they are unstable, that the wormhole closes or explodes as soon as you enter it. Therefore, we need a theory of everything.”
In order to get a theory of everything, Kaku said they should be able to use string theory. “That’s the first thing they would have to do, take a theory of everything like string theory, which is finite, calculate quantum corrections, show the wormhole is stable so you can do something with it, and show that it also makes sense,” he said. “People like to go in the opposite direction. They would like to start with this equivalence as an opening gambit and from that derive a quantum theory of space time, which I think is an ambitious proposal, but I tend to be skeptical unless you can really calculate quantum corrections, which are notoriously difficult to calculate.”
Though a theory of everything remains elusive to physicists, if one is developed and agreed upon, it will answer some of the deepest questions that philosophers and theologians have grappled with for centuries.
“Are there other dimensions? Are there other universes? Can we travel between universes? What about time travel? What happened before the big bang? None of these questions are answerable with today’s technology,” said Kaku. “However, all of them are answerable if we have a theory of everything, like string theory. String theory at the present time is not advanced enough in terms of our human understanding to answer these questions, but it has within it the capability of answering all of the above.”