Why Does Time Slow Down When You Move Fast?

Imagine you're on a super-fast train, zooming past your friend who is standing still. To you, it feels like everything outside the train is moving really fast. But to your friend, you seem to be going by very quickly. Now, imagine that this train can go as fast as light itself. When you get off the train and meet up with your friend again, you'll notice something strange: you've aged less than your friend! This is called time dilation, a weird but true effect of moving really fast.

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Examples

  1. If you were on a super-fast train going almost as fast as light, your friend on the platform would see you aging more slowly.
  2. Imagine two people who are twins, one stays on Earth, the other travels in space at nearly the speed of light and returns years later to find that they’ve aged differently.
  3. A clock that’s moving very fast ticks slower compared to a clock that is standing still.

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