Wormholes, which are strange hypothetical tunnels through space-time, could act as cosmic magnifying glasses for objects behind them.
If wormholes – strange tunnels connecting two regions of space-time – exist, we may be able to spot them by the way they magnify light. This phenomenon, in which light from behind a cosmic object is stretched around the object due to its gravitational field, is called gravitational lensing, and wormholes may be some of the most powerful lenses around.
Wormholes connect two points in space-time (if they exist)Gravitational lensing is fairly common in space and is used to probe some of the biggest mysteries of the universe, including dark matter and the finer points of general relativity, so understanding the lensing signatures of various cosmic objects is crucial. Mian Zhu at the Hong Kong University of Science and Technology in China and his colleagues calculated how a wormhole with an electric charge would magnify and warp the light of objects behind it – an understanding that could also help in the search for wormholes.
“Certain wormholes can produce the same observational signals as those from black holes,” says Zhu. “In view of that, it is important to study these hypothetical objects, and see whether we can distinguish them from black holes.”
They found that while it would be difficult or, in some cases, impossible to distinguish any individual wormhole from a black hole, between groups of each there could be small differences.
Gravitational lensing splits and warps light in such a way that it often produces multiple images of an object. For black holes, the process can result in any number of copies. But for charged wormholes, the researchers found that there can only be either one image or three.
If there are three, one of them should be extremely bright and the other two should be slightly dimmer, but with the same brightness as one another. In these images, gravitational lensing can magnify an object by as much as 100,000 times. If a group of potential wormholes each produced this pattern, that could help confirm that they were wormholes rather than black holes.
The powerful magnification would also be useful for studying the objects being magnified, but it still doesn’t guarantee that we could tell what was doing the magnifying. “The search for dark objects with high precision just began, and we don’t have enough evidence to prove or disprove the existence of wormholes yet,” says Zhu. “What we can do currently is to predict the possible unique signature from these dark objects, and leave the right of judgement to future observations.”
Journal reference: Physical Review D, DOI: 10.1103/PhysRevD.107.024022
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