Wormholes play a key role in many sci-fi movies – often as a portal between two distant points in space. However, in physics, these tunnels in space-time remained purely hypothetical objects. However, scientists recently presented a new theoretical model that makes microscopic wormholes more real than previous theories.
Wormholes, like black holes, appear in the equations of general relativity (GR) by Albert Einstein, published in 1916. An important postulate of Einstein’s theory is that the universe has four dimensions: three space and time as the fourth dimension. Together they form space-time, which can be stretched and curved by massive objects like stars. This is similar to how a rubber sheet bends under a metal ball plunging into it.
The curvature of space-time determines how such objects move in it – spaceships and planets, as well as light. “In theory, spacetime can be bent and bent without massive objects,” explains Blasquez-Salcedo, one of the study’s authors. In this scenario, the wormhole will be an extremely curved region in spacetime. It resembles two interconnected funnels and connects two distant points in space, like a tunnel. “From a mathematical point of view, such a short path would be possible, but no one has ever observed a real wormhole,” the physicist emphasizes.
Moreover, such a wormhole would be unstable. If, for example, a spaceship flies into one of them, it instantly collapses into a black hole – an object in which matter disappears, and it is no longer possible not to see it. The connection that he will provide with other places in the universe will be interrupted. Previous models suggest that the only way to keep the wormhole open is to use an exotic form of matter that has negative mass, or in other words, weighs less than zero and exists only in theory. However, Blazquez-Salcedo and his colleagues demonstrate with a model that wormholes can be traversed without such materials.
The researchers chose a relatively simple “semiclassical” approach. They combined elements of general relativity with elements of quantum theory and the classical theory of electrodynamics. In their model, they view certain elementary particles – electrons and their electric charge – as matter that must pass through a wormhole. They chose the Dirac equation as a mathematical description. This is a formula that describes the probability density function of a particle according to quantum theory and the theory of relativity as the so-called Dirac sea.
It is the inclusion of the Dirac field in their model that allows the existence of a wormhole that matter can cross. Provided that the ratio between the electrical charge and the mass of the wormhole exceeds a certain limit. Besides matter, signals – like electromagnetic waves – can also travel through tiny tunnels in spacetime. The team’s postulated microscopic wormholes do not appear to be suitable for interstellar travel. Moreover, the model will require further refinement in order to find out whether such unusual structures can really exist. “We think wormholes can also exist in a holistic model,” concludes Blazquez-Salcedo.