Rockets Don't Need Air to Push Against
The push that drives a rocket happens between the rocket and its own exhaust. Outside air isn't what it pushes against, which is why empty space doesn't stop it.
7 hours ago4 min read
The Lonely Brain That Shouldn't Outnumber Us
Give randomly jiggling atoms long enough and, very rarely, they could fall into the shape of a single working brain, complete with memories of a life it never lived. Some models of the universe seem to predict far more of these lonely minds than ordinary people. Physicists don't take that as news about reality. They take it as a sign that a theory has gone wrong.
7 hours ago6 min read
To Catch a Ripple in Space, Hang a Mirror and Keep It Very Still
A gravitational-wave detector rests on glass mirrors hung at the far ends of long laser arms. Its real trick isn't sensing motion. It's stopping almost every other kind of motion first.
7 hours ago5 min read