Traveling through the wormholes is possible, but slow

A Harvard physicist has shown that wormholes can exist: tunnels in a curved space-time, connecting two distant places, through which it is possible to travel.

But do not pack your bags for a trip to the other side of the galaxy yet; although this is theoretically possible, it is not helpful for humans to travel, said study author, Daniel Jafferis, of Harvard University, writing in collaboration with Ping Gao, also of Harvard and Aron Wall of Stanford University.

"It takes longer to cross these wormholes than to go straight, so they are not very useful for space travel," said Jafferis. He will present his findings at the April 2019 meeting of the American Physical Society in Denver.

Despite his pessimism for pan-galactic journeys, he said finding a way to build a wormhole through which light could move was a stimulus in the quest for a theory of quantum gravity .

"The true importance of this work lies in its relationship to the information problem about black holes and the links between gravity and quantum mechanics," said Jafferis.

The new theory was inspired when Jafferis began to think about two quantum-entangled black holes, as formulated in ER = EPR correspondence of Juan Maldacena of the Stanford Institute for Advanced Study and Lenny Susskind. Although this means that the direct connection between the black holes is shorter than the wormhole connection (and that, therefore, the wormhole path is not a shortcut), the theory provides new information on quantum mechanics.

"From an outside perspective, traveling through the wormhole is equivalent to quantum teleportation using entangled black holes," said Jafferis.

Jafferis based his theory on a configuration first conceived by Einstein and Rosen in 1935, consisting of a connection between two black holes (the term wormhole was coined in 1957). As the wormhole is traversable, said Jafferis, this was a special case in which information could be extracted from a black hole.

"This gives a causal analysis of areas that would otherwise have been located behind a horizon, a window on the experience of an observer in a space-time, accessible from the outside," Jafferis said.

Until now, one of the main obstacles to the formulation of crossworm holes was the need for negative energy, which seemed incompatible with quantum gravity. Jafferis, however, overcame this problem by using quantum field theory tools, computing quantum effects similar to those of Casimir.

"I think that will teach us a lot about gauge / gravitation correspondence, quantum gravity and maybe even a new way of formulating quantum mechanics," said Jafferis.