Albert Einstein’s theory of general relativity profoundly changed our thinking about fundamental concepts in physics, such as space and time. But it also left us with deep mysteries. One was black holes, which have only been unequivocally detected in recent years. Another were “wormholes” – bridges connecting different points in space-time, theoretically providing shortcuts for space travelers.
Wormholes are always a matter of the imagination. But some scientists think we’ll be able to find them soon, too. In recent months, several new studies have suggested interesting leads.
Black holes and wormholes are special types of solutions to Einstein’s equations, occurring when the structure of space-time is strongly bent by gravity. For example, when matter is extremely dense, the fabric of space-time can become so curved that even light cannot escape. It’s a black hole.
As the theory allows to stretch and bend the fabric of space-time, one can imagine all kinds of possible configurations. In 1935, Einstein and physicist Nathan Rosen described how two sheets of space-time can come together, creating a bridge between two universes. It’s kind of a wormhole – and many more have been imagined since.
Some wormholes can be “traversable,” which means humans may be able to pass through them. For this, however, they should be large enough and held open against the force of gravity, which attempts to close them. To push space-time out in this way would require enormous amounts of “negative energy”.
Does this sound like science fiction? We know negative energy exists, small amounts have already been produced in the lab. We also know that negative energy is the source of the accelerated expansion of the universe. So nature may have found a way to make wormholes.
Spot wormholes in the sky
How can we ever prove that wormholes exist? In a new article, published in the Monthly Notices of the Royal Society, Russian astronomers suggest that they may exist at the center of some very bright galaxies and offer some observations to find them. This is based on what would happen if material coming out of one side of the wormhole collided with material falling into it. Calculations show that the crash would result in a spectacular display of gamma rays that we could try to observe with telescopes.
This radiation could be the key to differentiating a wormhole and a black hole, previously assumed indistinguishable from the outside. But black holes would have to produce fewer gamma rays and eject them in a jet, while radiation produced through a wormhole would be confined to a giant sphere. Although the kind of wormhole considered in this study is traversable, it would not make a pleasant trip. Because it would be so close to the center of an active galaxy, the high temperatures would burn everything to a crisp. But that wouldn’t be the case for all wormholes, such as those farther from the galactic center.
The idea that galaxies may have wormholes in their centers is not new. Take the case of the supermassive black hole at the heart of the Milky Way. This was discovered by careful tracking of the orbits of stars near the black hole, a major achievement that received the Nobel Prize in Physics in 2020. But a recent article suggested that this gravitational pull might instead be caused by a wormhole. .
Unlike a black hole, a wormhole can “run away” from a certain gravity of objects on the other side. This frightening gravitational action would add a little kick to the movements of stars near the galactic center. According to this study, the specific effect should be measurable in observations in the near future, once the sensitivity of our instruments is a little more advanced.
Coincidentally, another recent study reported the discovery of some “strange radio circles” in the sky. These circles are strange because they are huge and yet not associated with any visible object. For now, they defy conventional explanation, so wormholes have been put forward as a possible cause.
A box of worms
Wormholes hold a strong hold on our collective imagination. In a way, they are a delicious form of escape. Unlike black holes which are a bit scary as they trap anything that ventures out, wormholes can allow us to travel to faraway places faster than the speed of light. In fact, they may even be time machines, offering a way to travel backwards – as the late Stephen Hawking suggests in his latest book.
Wormholes also appear in quantum physics, which governs the world of atoms and particles. According to quantum mechanics, particles can come out of empty space, only to disappear an instant later. This has been seen in countless experiments. And if particles can be created, why not wormholes? Physicists believe that wormholes may have formed in the early universe from a foam of quantum particles entering and exiting existence. Some of these “primordial wormholes” may still exist today.
Recent experiments on “quantum teleportation” – a “disembodied” transfer of quantum information from one location to another – have been found to work in a way that is eerily similar to two black holes connected by a wormhole. These experiments appear to resolve the “quantum information paradox,” which suggests that physical information could disappear permanently in a black hole. But they also reveal a deep connection between the notoriously incompatible theories of quantum physics and gravity – wormholes being relevant to both – that may play a role in building a “theory of everything.”
The fact that wormholes play a role in these fascinating developments is unlikely to go unnoticed. We may not have seen them, but they sure could be there. They can even help us understand some of the deepest cosmic mysteries, such as whether our universe is the only one.
How to see what’s on the other side of a wormhole without actually walking through it
Provided by The Conversation
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