Travel through a wormhole survivable?

The effect of gravity and tidal forces on a passing object

Theoretically, there could be wormholes in the cosmos - but would a passage through it be possible? © Fred Mantel / thinkstock
Read out

Extreme, but supernatural: physicists have investigated whether a physical object could survive passage through a wormhole without being dissected by the tremendous forces into its elementary particles. Their result: Although they spaghetti and exposed in the funnel of the wormhole tremendous tidal forces. Theoretically, however, these forces are finite - and that's the way to counteract them.

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

Can there be wormholes?

However, the conditions for such wormholes to exist are so exotic that their existence has previously been thought impossible. In addition, such a tunnel would be unstable in space-time, and the cylindrical passageway between the two black holes would quickly disintegrate into two singularities - and thus a trap without recurrence.

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

"Painful spaghetti"

The Theory of Relativity says that a body approaching a black hole will be extremely pulled apart in the longitudinal direction. "The fate of an all too curious observer is to experience a painful spaghetti by the strong tidal forces before it is destroyed in the center of a black hole "Explains the physicist Jennifer Sanders in an accompanying commentary. display

In the wormhole, the spacetime is curved into two interconnected funnels. Uli Yuli4ka / thinkstock

However, as Rubiera-Garcia and his colleagues have now determined, an object might still be able to pass through a wormhole, albeit not in a very good condition. According to their calculations, a person would spaghetti it, but only to the extent that its diameter matches that of the wormhole.

Fatal tidal forces

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

This effect causes the individual particles in the body of the glaucous wormhole traveler to be compressed and pulled apart by extreme tidal forces. If its individual parts fail to remain in a causal relationship with one another, despite spaghettisation, for example through physical or chemical interactions, then the complete destruction is the result. But can a material object fundamentally outstretch the tidal forces in the wormhole?

Extreme, but surpassable

According to the researchers, the answer is yes. Because as you demonstrate in the model, the spatial distance between two geodesic lines in the wormhole is always finite. As a result, a beam of light could still radiate from one particle of the object to another and transmit information, for example. A causal connection would thus remain.

This means for the passage through the wormhole: Although one would use tremendous forces to maintain the integrity of the traveler, but theoretically this would be possible. The entry into a wormhole is therefore - unlike a single black hole - not automatically equivalent to the end of existence. However, whether a person will ever make such a journey and survive will remain questionable. (Classical and Quantum Gravity, 2016; doi: 10.1088 / 0264-9381 / 33/11/115007)

(Institute of Astrophysics and Space Science Lisbon, 10.06.2016 - NPO)