The Speed of Light
You could say that Special Relativity says all speeds are relative.. except for one.. the speed of light. It’s the same for every observer no matter how they are moving and no matter how the source of light is moving. Relativity did not produce this result, Einstein fed it in as a postulate. And the rest is history.
Let's explain it plainly.
You're standing by the railway tracks. I come speeding past in my new engine going at 0.9c. I switch on the headlights and you measure the speed of light from them. It should be 0.9c+c=1.9c. Right? Wrong. The result you get is still c.
Content written and posted by Ken Abbott firstname.lastname@example.org