Why Does Time Slow Down Near Massive Objects?

Imagine spacetime is like a giant trampoline. When you put a heavy bowling ball in the middle, it creates a dip. This dip is what we feel as gravity. But here is the weird part: time also gets stretched out in that dip.

Think of time as a river flowing smoothly. Near Earth, the river flows at a normal speed. But if you go to space far away from Earth, the river speeds up slightly because there is less heavy mass pulling on it. This means clocks in space tick faster than clocks on the ground.

You can actually see this happen! GPS satellites orbit high above us where gravity is weaker. Their clocks run about 45 microseconds faster every day than clocks on Earth. If engineers did not fix this difference, your phone would think you were several miles off when asking for directions. It proves that mass literally slows down time itself.