Microscopic wormholes are possible in theory

Wormholes play a key role in many science fiction films – often as a shortcut between two distant points in space. In physics, however, these tunnels have remained purely hypothetical in space-time. An international team led by Dr Jose Luis Blázquez-Salcedo of the University of Oldenburg has now presented a new theoretical model in the scientific journal Physical overview letters which makes microscopic wormholes appear less far-fetched than in previous theories.

Wormholes, like black holes, appear in the equations of Albert Einstein’s general theory of relativity, published in 1916. An important postulate of Einstein’s theory is that the universe has four dimensions – three spatial dimensions and time as the fourth dimension. Together they form what is known as space-time, and space-time can be stretched and bent by massive objects such as stars, just as a rubber sheet would be bent by a metal ball sinking into it.

The curvature of space-time determines the way objects such as spaceships and planets, but also light, move in it. “In theory, space-time can also be bent and flexed without massive objects,” says Blázquez-Salcedo, who has since been transferred to the Complutense University of Madrid in Spain. In this scenario, a wormhole in space-time would be an extremely curved region that looks like two interconnected funnels and connects two distant points in space, like a tunnel. “From a mathematical perspective, such a shortcut would be possible, but no one has ever observed a true wormhole,” the physicist explains.

Moreover, such a wormhole would be unstable. For example, if a spaceship were to fly in one, it would immediately collapse into a black hole – an object in which matter disappears, never to be seen again. The connection it offered to other places in the universe would be cut off. Previous models suggest that the only way to keep the wormhole open is with an exotic form of matter that has a negative mass, or in other words weighs less than nothing, and that exists only in theory. Blázquez-Salcedo and his colleagues dr. However, Christian Knoll of the University of Oldenburg and Eugen Radu of the Universidade de Aveiro in Portugal demonstrate in their model that wormholes can be movable even without such matters.

The researchers chose a relatively simple “semi-classical” approach. They combined elements of relativity theory with elements of quantum theory and classical electrodynamics theory. In their model, they consider certain elementary particles such as electrons and their electric charge as the matter that must pass through the wormhole. As a mathematical description, they chose the Dirac equation, a formula that describes the probability density function of a particle according to quantum theory and relativity as a so-called Dirac field.

As the physicists report in their study, it is the inclusion of the Dirac field in their model that allows the existence of a wormhole movable by matter, provided that the ratio between the electric charge and the mass of the wormhole exceeds a certain limit. In addition to matter, signals – for example electromagnetic waves – can also traverse the small tunnels in space-time. The microscopic wormholes posed by the team are unlikely to be suitable for interstellar travel. The model needs to be further refined to find out if such unusual structures can exist. “We think wormholes can also exist in a complete model,” says Blázquez-Salcedo.

Provided by the University of Oldenburg