Why do massless particles not experience time?
In: Physics
I don’t know that we can explicitly state they don’t experience time. However, the experience of time for an object relates to the frame of reference in which it is stationary. Massless objects don’t have a stationary reference frame, they move at c in all frames of reference. So a stationary frame of reference is undefined.
In other words, if you’re in a train going at 60mph, we can pick a frame of reference where you’re stationary and the earth is going past you at 60mph, and we can talk about what time means to you in it. A massless particle has no such frame of reference.
Relativity plays a role here. The faster an object goes, the slower it traverses through time. Objects with mass require energy to accelerate them, thus their velocity through space is limited and they will experience at least some passage through time. A massless object is not bound by this and can have the highest velocity in space that we currently believe is possible (the speed of light), and at that velocity, passage through time ceases.
With relativity you have to think about space and time as a unified whole, not two separate phenomina. And, more surprisingly, we are all moving through spacetime at the same speed: the “speed of light” *c*. Objects moving extremely fast through space experience less time, and objects which are moving slowly experience time more “normally”. But, regardless, if you move fast in one you move slowly in the other but the total magnitude of your velocity through spacetime is always *c*.
Now, apply that concept to a massless particle like a photon: It has no mass so it moves through space at speed *c*, but that means there’s nothing left in it’s velocity vector for it to travel through time.
For further reading:
[https://medium.com/predict/we-all-travel-through-spacetime-at-the-speed-of-light-d60cb389dfc2](https://medium.com/predict/we-all-travel-through-spacetime-at-the-speed-of-light-d60cb389dfc2)
[https://physics.stackexchange.com/questions/33840/why-are-objects-at-rest-in-motion-through-spacetime-at-the-speed-of-light](https://physics.stackexchange.com/questions/33840/why-are-objects-at-rest-in-motion-through-spacetime-at-the-speed-of-light)
[https://www.quora.com/Does-everything-travel-at-the-speed-of-light-in-spacetime](https://www.quora.com/Does-everything-travel-at-the-speed-of-light-in-spacetime)
Big mass pulls other mass but with massless particles there is no mass for big mass to pull. Oh and the pulling from Big mass makes time, so since it doesn’t pull and make gravity time doesn’t wanna work correctly
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