Forty years ago, Canadian physicist Bill Unruh made a surprising prediction regarding quantum field theory. Known as the Unruh effect, his theory predicted that an accelerating observer would be bathed in blackbody radiation, whereas an inertial observer would be exposed to none. What better way to mark the 40th anniversary of this theory than to consider how it could affect human beings attempting relativistic space travel?
It’s easy to assume that astronauts float in space because they are far away from the Earth’s gravitational force. But look at the moon. It is much further away than the International Space Station, yet it orbits around the Earth because it is perpetually attracted by its gravitational pull. So if the Earth’s gravity can affect the moon, the astronauts cannot be floating because there is no gravity where they are.