Why Does Time Run Slower Near Earth?

Imagine two twin clocks. One sits on a heavy pillow, and the other floats in space. The one on the pillow ticks slower because its weight squishes the fabric underneath it. This is gravity stretching time!

Light travels at a set speed. If you are deep in a gravity well (like Earth), light has to work harder to climb out, which stretches the waves of time.

GPS satellites orbit high above us where gravity is weaker. Their clocks tick faster than ours on the ground. If engineers did not fix this tiny difference, your map app would be off by miles! So next time you look at the sky, remember that time there is ticking just a little bit quicker.