Why Is Time Slower When You're Moving Fast?

Imagine you're on a super-fast train. To someone standing still, your clock ticks slower than theirs, it's like the train is playing everything in slow motion. But to you, everything looks normal. Time feels different depending on how fast you go.

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Examples

A person on a fast spaceship ages slower than someone who stayed on Earth.
Your watch would tick slower if you ran around a race track at nearly light speed.
If you traveled to another planet and came back, you might be younger than your twin.

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Categories: Physics · relativity· time dilation· motion and time· special relativity· speed and perception