If aliens were to make spacecraft as massive as Jupiter or ones that use warp drives, we might be able to detect them using the ripples they produce in space-time
9 December 2022
We may be able to spot enormous alien spacecraft by the gravitational waves they would create. Gravitational waves are ripples in space-time formed when a massive object moves around, so if there are any extraterrestrials driving gigantic spacecraft around our galaxy, the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the US could potentially detect them.
Gianni Martire at Applied Physics, a research institute in New York, and his colleagues calculated how large such a craft would have to be, and how fast it would have …