The universe is full of exciting things, like black holes or merging neutron stars. However, all this looks trite compared to what scientists call wormholes, which hypothetically connect parts of space in different parts of the universe.
Many physicists are skeptical that wormholes exist, or at least that three-dimensional objects can pass through them unharmed.
As telescopes develop, a more and more exciting question arises: if wormholes exist, why have we never discovered them? Four Bulgarian physicists believe that perhaps we simply did not recognize them.
Most of the black holes we’ve identified are known either from their gravitational effects on the stars around them or from the jets of material ejected from their accretion disks. If any of them were indeed wormholes, we would be unlikely to know about it.
However, observing the polarization around M87* with the Event Horizon Telescope and its follow-up to Sagittarius A* is another matter entirely. In these cases, we saw the shadow of the object itself on its event horizon and hoped to spot something that looked like a wormhole.
The possibility of wormholes excites physicists, however, as Petya Nedkova and co-authors of the study from Sofia University note, we do not know what they might look like.
Scientists in their study are trying to solve this problem and come to the conclusion that, when viewed from a large angle, wormholes will not look like anything we have previously seen.
However, the authors believe that at low tilt angles, the wormhole will have a “very similar polarization pattern” to a black hole. Therefore, M87*, seen at the assumed angle of 17°, could be a wormhole and we would not know it.
This does not mean that we are absolutely unable to distinguish between wormholes and black holes.
“More significant differences are observed for highly lensed indirect images, where the polarization intensity of a wormhole can increase by an order of magnitude compared to a black hole,” the authors write.
The lensing does not come from a massive object between us and the hole creating a gravitational lens. The photons’ trajectories are distorted by the hole’s huge gravitational field, causing them to make a partial loop around the hole before heading towards us.
The situation becomes even more complicated if we assume that matter or light can pass through the wormhole in any direction. If so, then signals from the area outside the entrance are able to reach us.
They will change the polarized image of the disk that we see around the hole, while the light coming from another place will have different polarization properties. This can provide what the authors call “a characteristic signature for wormhole geometry detection.”
The authors of the study acknowledge that their findings are based on a “simplified model of a ring of magnetized fluid” orbiting a black hole. More advanced models will help identify differences and use them to distinguish a wormhole from a black hole in other ways.
Article published in Physical Review D.