Why does gravity pull us down and not up?
Gravity is the reason things with mass or energy are attracted to each other. It is why apples fall toward the ground and planets orbit stars.
Magnets attract some types of metals, but they can also push other magnets away. So how come you feel only the pull of gravity?
In 1915, Albert Einstein figured out the answer when he published his theory of general relativity. The reason gravity pulls you toward the ground is that all objects with mass, like our Earth, actually bend and curve the fabric of the universe, called spacetime. That curvature is what you feel as gravity.


Chapter 1: Introduction to Gravity and General Relativity

Chapter 2: The Concept of Mass and Energy in Relation to Gravity

Chapter 3: The Bending and Curvature of Spacetime

Einstein’s Insight: Why Does Gravity Pull Us Down and Not Up?