According to Einstein’s general relativity, massive objects bend the fabric of spacetime, manipulating the gravitational force around them. Black holes are notorious for being so massive that they bend spacetime onto themselves, creating a gravitational pull so strong that not even light (the fastest moving thing in the universe) can escape. General relativity recently suggested yet another outlandish possibility in physics: wormholes hosting massive objects.
Physicists believe the roles of time and space switch within black holes due to the theory of relativity.
Normally, one can only travel forward through the arrow of time. When a cup drops, one cannot reverse the events to recollect the glass into its former state. While there is no freedom in time, one has complete control over where they travel in space. Up, down, left, and right; all are possible. Humans have a choice of where, but never when. Conditions differ inside a black hole, as an extreme event scientifically coined as gravitational time dilation occurs.
According to general relativity, time is relative. If one twin lived their life on earth, and the other lived their life on the international space station, the one on Earth would be older by a few seconds due to gravitational time dilation. The stronger the gravity, the greater the dilation or time difference. In the most extreme of cases, like in black holes, gravity dilates time so much so that it comes to a halt; time stops flowing. However, due to the gravity pulling the object to the center of a black hole, restricting its ability to escape, objects are limited to one direction, towards the center of the black hole. In a black hole, one can never decide where.
According to a special solution to the Einstein field equations, in a wormhole, one could theoretically open a portal through spacetime, creating shortcuts across the universe. Since general relativity states that mass and energy warp spacetime, wormholes can be created by a specific configuration of mass and energy. While many argue they cannot exist in nature, some believe in the possibility of their existence.
“In theory, space-time could be bent and curved without massive objects [such as black holes]. In this scenario, a wormhole would be an extremely curved region in space-time that resembles two interconnected funnels and connects two distant points in space, like a tunnel,” Dr. Jose Luis Blázquez-Salcedo, a researcher in the Departamento de Física Teórica and IPARCOS at the Universidad Complutense de Madrid said. “From a mathematical perspective such a shortcut would be possible, but no one has ever observed a real wormhole.”
Wormholes would be theoretically unable to carry massive objects due to their incredible instability, a factor which would cause them to instantly turn into a black hole. The only thing that could traverse through a wormhole would be something with negative mass. Such an object would disobey energy laws. If one pushes a regular object, it will accelerate in the direction they are pushing it. In the case of negative mass, things are opposite.
“With negative mass, if you push something, it accelerates toward you,” Michael Forbes, a WSU assistant professor of physics and astronomy and an affiliate assistant professor at the University of Washington said.
Due to the extreme conditions necessary to sustain negative mass objects, it would be difficult to observe them traverse through a wormhole.
However, a new study by Dr. Blázquez-Salcedo and his colleagues from the Universität Oldenburg and the Universidade de Aveiro suggested that wormholes could be traversable without such exotic matter.
To test their theory, the researchers used elementary particles, like electrons, as the matter that would pass through the wormhole.
To mathematically describe the phenomenon, the researchers used the Dirac equation: a formula that uses the Dirac field to describe the probability density function of a particle according to relativity and quantum mechanics.
“It’s the inclusion of the Dirac field into our model that permits the existence of a wormhole traversable by matter, provided that the ratio between the electric charge and the mass of the wormhole exceeds a certain limit,” the researchers said.
With their use of electrons, they found that the electron (matter) and its signals (electromagnetic waves) were both able to traverse through their theoretical wormhole.
The model suggests that the use of wormholes is not exclusively possible for objects with negative mass. However, this does not mean that humans and other large objects can achieve travel through wormholes, as wormholes are too unstable to carry such mass through space. To add insult to injury, the researchers’ model was only a theoretical postulation of the possibility of matter to travel through a wormhole.
“Moreover, the model would have to be further refined to find out whether such unusual structures could actually exist,” the researchers said.
As always in the world of theoretical physics, all remains relative, and nothing remains certain.