How do we know if wormholes exist?
We don’t know if wormholes exist, but if they do, it’s likely that one day we will find them. Traversable wormholes are unlikely to exist, since there are no known physical mechanisms that can create them or keep them open. A hypothesised form of matter with antigravity effects may keep wormholes open. However, no such exotic matter has ever been observed.
Despite the unlikely odds, some scientists are thinking of how to detect wormholes. Some wormholes are black hole ‘mimickers’ – they have a positive effective mass, which means they act like black holes. A wormhole may bend the light from a star by passing in front of it in an effect called gravitational microlensing. Other wormholes may have an accretion disc, like supermassive black holes. The light from this disc can encode information about the space-time distortion around the wormhole, which may be different than around a black hole.
It may also become possible to image the shadow of a wormhole directly, just as it was done recently for the black hole in Messier 87. Wormholes may stand out by having differently shaped shadows. The detection of gravitational waves from a black hole merging with a wormhole could also be within reach of next-generation gravitational observatories.
Dr Andreea Font, reader in theoretical astrophysics, Liverpool John Moores University