Forces reckoned with

I am standing on the threshold about to enter a room. It is a complicated business. I must shove against an atmosphere pressing with a force of 14lbs on every square inch of my body. I must make sure of landing on a plank travelling at 20 miles a second round the sun . I must do this whilst hanging from a round planet, head outward into space, and with a wind of aether blowing at no one knows how many miles a second through every interstice of my body.

Astrophysicist Arthur Eddington (1882-1944) on opening a door.