快猫短视频

We might be able to tell the difference between a wormhole 鈥� a tunnel that connects two black holes at different locations in space-time 鈥� and a regular black hole using light that has travelled in circles around the black hole鈥檚 mouth. If wormholes exist, this could finally allow astronomers to spot them.

In 2019, astronomers used a network of radio observatories called the Event Horizon Telescope (EHT) to take the first direct image of a black hole, a distant behemoth called M87*. at Sofia University in Bulgaria and her colleagues set out to determine whether we could use the EHT data on the polarisation of light from around the black hole to distinguish between a traversable wormhole and a black hole.

鈥淭en years ago, wormholes were completely in the area of science fiction; now, they are coming forward to the frontiers of science and people are actively searching,鈥� says Nedkova. 鈥淪o we are slowly making a register of all the observational signatures of black holes and wormholes and looking one by one at which ones are promising for future detection.鈥�

Using a set of computer models, they found that direct light 鈥� light emitted in the area around the black hole that travels straight to our observatories 鈥� doesn鈥檛 provide data with enough detail to distinguish between the two. The difference in the amount of polarisation between a black hole and a wormhole would be less than 4 per cent, and the difference in polarisation direction would be even smaller.

鈥淲ith the current observations, you cannot distinguish a black hole or a wormhole 鈥� there may be a wormhole there but we cannot tell the difference,鈥� says Nedkova. 鈥淪o we were looking for something else up there in the sky that could be a way to distinguish black holes from wormholes.鈥�

Next, the researchers modelled higher-energy light, which is emitted closer to the black hole and dragged at least halfway around it by the black hole鈥檚 powerful gravity before heading towards Earth. They found that because of the differences in the shape of space-time, the light that has travelled around a wormhole could be more than eight times as polarised as the same light from a regular black hole, with a difference in the direction of polarisation of up to 50 per cent. However, we do not yet have reliable observations of this kind of light from around a black hole.

The researchers also examined one other option, perhaps more speculative than the others. If a wormhole is traversable, like the one they used in their models, that means that light must be able to travel through it from the other end and emerge from the black hole we can observe. If that occurred, the researchers found that the gravitational effects within the wormhole could make that light emerge more than six times as bright as the light around the black hole at our end, as well as creating several small rings of light near the black hole.

So while we might not be able to tell the difference between a black hole and a wormhole with the data we have now, it is theoretically possible. For that, we will need telescopes with higher resolution, rather than trying to get up close and personal with a black hole. 鈥淚f you were nearby, you would find out too late,鈥� says Nedkova. 鈥淵ou鈥檒l get to know the difference when you either die or you pass through.鈥�

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