Can we travel through the wormhole in time?

Can you survive a trip through a wormhole?

Extreme, but survivable: Physicists have investigated whether a physical object could survive the passage through a wormhole without being broken down into its elementary particles by the enormous forces. The result: you are spaghetti and exposed to enormous tidal forces in the funnel of the wormhole. Theoretically, however, these forces are finite - and this could be used to counteract them.

They have long existed in Hollywood films, series such as “Deep Space 9” or science fiction novels: wormholes as a connection between distant regions of the universe. But also in Albert Einstein's theory of general relativity there are mathematical solutions under which such “space-time tunnels” exist. Two black holes would be connected by an area in which space-time is extremely curved, but does not end in a singularity, as is normally the case with black holes.

Can there be wormholes?

However: The conditions for such wormholes to exist are so exotic that their existence was previously thought to be impossible. In addition, such a tunnel would be unstable in spacetime and the cylindrical passage between the two black holes would quickly disintegrate into two singularities - and thus into a trap of no return.

Diego Rubiera-Garcia from the University of Lisbon and his colleagues see it differently, however. You recently demonstrated in a theoretical study that wormholes could well exist in the cosmos. Now they have taken a closer look at what consequences the passage through such a wormhole would have for solid objects, a person or the light.

"Painful spaghetti"

The theory of relativity says that a body approaching a black hole is extremely stretched lengthways. “The fate of an overly curious observer is to experience painful spaghetti due to the strong tidal forces before it is then destroyed in the center of a black hole “, Explains the physicist Jennifer Sanders in an accompanying comment.

In the wormhole, space-time is curved into two connected funnels. © Yuli4ka / thinkstock

But as Rubiera-Garcia and his colleagues have now discovered, an object could still survive a passage in a wormhole - even if not in a particularly good condition. According to your calculations, a person would be spaghetted, but only to the extent that his diameter corresponds to that of the wormhole.

Fatal tidal forces

This raises the question of whether an object could survive this process intact if it were extremely flexible and compressible. Because even if the space-time tunnel is permeable, extreme gravitational forces act in its narrowing entrance funnel: "Each particle of the object follows a geodetic line that is determined by the gravitational field," explains Rubiera-Garcia. "Each of these lines feels a slightly different force of gravity."

This effect causes the individual particles in the body of the hapless wormhole traveler to be compressed and pulled apart by extreme tidal forces. If its individual parts do not manage to remain in a causal relationship with one another despite the spaghetti, for example through physical or chemical interactions, the result is complete destruction. But can a material object withstand the tidal forces in the wormhole in principle?

Extreme, but survivable

According to the researchers, the answer to this is “yes”. Because as you demonstrate in the model, the spatial distance between two geodetic lines in the wormhole always remains finite. A beam of light could still shine from one particle of the object to another and, for example, transmit information - a causal connection would therefore be preserved.

For the passage through the wormhole, this means that enormous forces would be required to maintain the integrity of the traveler, but theoretically this would be possible. Entering a wormhole is therefore - unlike a single black hole - not automatically synonymous with the end of existence. However, it remains questionable whether a person will ever undertake and survive such a journey. (Classical and Quantum Gravity, 2016; doi: 10.1088 / 0264-9381 / 33/11/115007)

(Institute of Astrophysics and Space Science Lisbon, 06/10/2016 - NPO)

June 10, 2016