There is no universally accepted upper limit on interstellar flight speeds, but studies tend to converge around 19,000 miles per second (30,000 km/s) – 10% of the speed of light – as a realistic ...

Harvard professor Avi Loeb believes that aliens are not going to visit Earth in physical form, and would instead send a "technological device guided by AI". Their visit would not be fun either, and ...

A leading British astrophysicist has argued that intelligent alien civilisations 'absolutely' exist somewhere in the cosmos ...