Ask Ethan: Is Zero Gravity Really A Thing? (Synopsis) [Starts With A Bang]

“It was a strange lightness, a drifting feeling. Zero gravity. I understood that everything that once seemed solid and immovable might just float away.” -Lisa Unger

If you want to experience zero gravity, all you need to do is go to space, turn your rocket off and feel that weightless sensation, right? Except, from up there in Earth’s orbit, the gravitational force on you is still almost as great as it is on Earth’s surface! You still accelerate down towards the center of the Earth, not quite at 9.8 m/s^2, but not by much less.

There’s no place in the Universe where you can go to hide from the long-range force of gravity; its effects reach everywhere. So how, then, can we claim to truly know what it’s like in a zero-gravity environment? Because zero gravity isn’t about turning gravity off; it’s about the forces we do (and don’t) experience on our bodies.

According to Einstein, free-fall and zero gravity are actually equivalent, although that’s far from obvious. Here’s the science behind why on this week’s Ask Ethan!