You are being pushed upward at 9.8 meters per second squared even as you stand still

Sit perfectly still in your chair and you are accelerating upward at 9.8 meters per second squared.

That is the argument of Derek Muller, a physicist and science communicator. What you feel in your feet is not gravity pulling you down. Gravity, in this view, is not a force at all. The only force on you is the floor pushing up.

The clue is weightlessness. Picture a man who has fallen off a roof. While he falls, he feels no weight, and anything he drops stays floating beside him. You do not feel that way. You feel heavy, which means something must be holding you up and pushing you off your natural motion.

That natural motion is what physicists describe as the straightest path an object can follow when nothing pushes it. A freely falling person follows it, so he feels nothing. Sitting here matches riding in a rocket accelerating through deep space, where a traveler also feels the floor press into his feet.

The clearest way to measure your motion is by what the falling man would see. Relative to your floor, your chair, and the walls around you, you are not moving. But those things are all being pushed too. Seen by the falling man, with nothing pushing on him, you are coming upward toward him.

If everyone around the world is accelerating upward, why is the Earth not expanding? Because in curved spacetime, you can accelerate even while your position stays fixed. Staying in the same place takes a steady upward push from the ground, which keeps you from following your natural falling path.

As Muller puts it, “In curved spacetime, you need to accelerate just to stand still.”