Click anywhere on the canvas to spawn bodies. They attract each other following Newton's law of universal gravitation. Drag to give them initial velocity. Watch chaos emerge from simplicity.
Einstein showed gravity isn't a force — it's the curvature of spacetime itself. Move your cursor across the grid to warp it with mass. Massive objects tell spacetime how to curve; curved spacetime tells objects how to move.
Galileo's insight: in a vacuum, a feather and a bowling ball hit the ground at the same time. Toggle air resistance to see how drag deceives our intuition. Adjust gravity to see how different worlds feel.
Your mass never changes — but weight is the force gravity exerts on that mass. Enter your Earth weight and see how heavy you'd feel across the solar system.