I love the movie Interstellar but I have never fully understood how time dilation works. More recently reading “Project Hail Mary” this term came up again and I went on a Wikipedia binge trying to understand how it works.
How can time be different based on how fast you travel? Isn’t one second, one second everywhere? (I’m guessing not otherwise there would be no time dilation) but I just don’t understand what causes it or how to wrap my head around it
In: Physics
It’s a consequence of the speed of light being the same everywhere. At non-relativistic speeds, velocity is basically additive; if you are on a train going 50 mph and you throw a ball at 10 mph, for outside observers not on the train, the ball is going 60 mph.
It doesn’t work like that for light. If you are going on a train going 0.5c (c is the speed of light), shining a flashlight forward doesn’t make that light go at 1.5c for someone not on the train. It just *always* goes at c.
And if the distance / speed can’t be modified, then the only thing that can change is the time it takes. Because outside the train it looks like the light travels farther (but again, the speed of light is constant), it **has** to take more time than it does inside the train.
The experience of one second would be the same for a person on the train or not, but relative to each other it’s not the same.
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