Relativity: Why Moving Clocks Run Slow
Relativity and the light clock
1:01 · 720p · With AI narration and captions. This sample was made with the same system as this service.
Narration (full text)
Click a time to play from that scene.
Why Moving Clocks Lag
Let's use a light clock to see why moving clocks run slow.
Light Speed Is the Same for All
In a vacuum, no matter how fast you move, you always measure the same speed of light.
The Light Clock
Imagine a clock made of two mirrors, with light bouncing back and forth between them. Each round trip is one tick.
Watching a Moving Clock
Seen from outside, the light in a moving clock travels a long, slanted path. Since the speed of light is the same, each tick takes longer, so the clock runs slow.
Faster Means More Delay
At everyday speeds the effect is tiny, but it grows as you approach the speed of light. At about 87% of light speed, the clock runs at half its normal rate.
Confirmed in the Real World
Short-lived muons from high in the sky reach the ground in large numbers because of this effect. GPS satellites also correct their clocks for relativity.
Moving Clocks Tick Slower
Because the speed of light is the same for everyone, moving clocks run slow.
Create 3D explainer videos like this sample from your documents and chat
Just attach product documents, drawings, or CAD data and tell the AI in chat what video you want. The AI plans the storyboard, builds the 3D scenes, and turns it into a video with narration and captions. You pay only for what you use (a rough guide is about 3,500 credits for a 1-minute video with 2 small revisions).
