In Physics, What Makes Light So Special?

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I know what the speed of light is basically the speed limit of everything in the universe, and no information can travel faster than light itself. Light also exhibits many interesting properties and also serves as a constant for many formulae and equations in physics. The space-time continuum changes depending on what fraction of the speed of light at which you are travelling.

However, why light? Why is light and only light the one “phenomenon” that dictates most of physics? What makes light so special? My apologies if the question is phrased kind of strange.

In: Physics

9 Answers

Anonymous 0 Comments

Because light is a very good reference point when talking about something like relativity. No matter what speed you’re going, the speed of light stays *constant.*

A good example I always heard was the baseball metaphor. Pretend you’re standing at the back of a moving bus going 20mph. You throw the ball towards the front at 20mph. Well, relative to you it’s going 20mph, but to somebody on the outside, the ball is going 40mph.

Light does not do this. Lets say the bus is still going 20mph and you are standing in the back and shine a flashlight towards the front. Well, according to the baseball method of adding it, the light should be going 20mph+C, right? No, it doesn’t since nothing can necessarily exceed the speed of light, and you cannot really ‘accelerate’ light, so the beam cannot go faster than the speed of light already is. The difference between this and the baseball metaphor, relative to you ***and*** the person outside the bus, the light is moving at the exact same speed.

This is why it’s super important, it’s essentially the only thing in the universe that stays constant no matter the reference point. Just like you said, it stays constant across every formula and equation you can think of.

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