Eli5: How does Light Travel if it Experiences no Time?

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Einstein’s Theory of Relativity states that light (as it is travelling obviously at the speed of light) is so fast that it experiences no (zero) time. Obviously light does move a distance, as thats how we see things as the light bounces off of objects into our eyes, but surely with the equation ‘distance = speed\*time’ and time being zero it implies light doesn’t travel any distance?

In: Physics

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Anonymous 0 Comments

Imagine a car going forwards at it’s maximum speed of 100mph. It’s sideways speed is 0mph. if we turn the car 90 degrees now it goes sideways at 100mph, but 0mph in the forward/backwards dimension.

It can travel diagonally, by moving 50mph in the forward/backward dimension, and 50mph in the left/right dimension, for a total speed of 100mph, the maximum.

If you think of Spacetime as 4 dimensions, 3 space and 1 time, light travels at the maximum speed C in 3 of the dimensions, space. This takes all of its “time speed”, making it’s time speed 0 and therefore experiences no time.

We see light move at C, which obviously takes time. This is because our perception of the light traveling can only go at the original maximum speed, so we see it moving. The light photon instantly travels to the destination, but it takes time for its effect to propagate outwards to observers.

Edit: diagonal speeds will not be 50mph. Vector maths means the speeds will be greater, which obviously also applies to spacial and time based motions

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