Hi anons! I'm someone who is extremely motivated to learn astrophysics and particle physics to the greatest degree. Anyway, I'm just getting started on learning spacetime, and something confuses me-why does moving close to the speed of light affect time and how you age? I understand that space and time can be one 4 dimensional plane, and that when you move close to the speed of light you are perceiving light slower than someone who is stationary in your frame of reference. But what I can't wrap my head around is why this slows your aging, since you're still moving slower than light. Can someone explain this to me?
>>12579070>slows your argingThis is a relative statement. Everybody experiences their own age normally. But if one person accelerates (e.g. moves away from you, then accelerates backwards and ends up next to you), then the time passed for that person is shorter. E.g. you stand still for 2 seconds (on your clock) and a person stepping away from you for a second (on your clock), making that turn and and coming back to you will in the next second (on your clock) have aged less than two seconds (in the sense that their bodies/carried clocks didn't see 2 full seconds)
>>12579070Here's a very simple exampleSay you have two spaceships A and B, and they can move at 51% the speed of lightA and B start moving away from each other—now, from A's perspective, how fast is B moving? 102% the speed of light? Well no that can't be it, so.. from A's perspective, B is moving slower. Not just B, but everything else is going to be moving slower.
It doesn't slow your aging, only the relative time experienced compared to an outside observer.
>>12579083Oh, so it's because time is literally light? So, if a person even slightly moves forwards in the direction of light, and then backwards, they will have travelled to the future, however miniscule it may be.
In a nutshell, time dilation occurs so that events happen simultaneously. If you're moving away from an event at half the speed of light and time doesn't dilate, in your perspective it would appear that the event happened after it actually occurred.Time dilation keeps all the events on the same page.
>>12579090Right, but i don't quite understand why. Say, for example, person A is standing completely still, but person B moves forward 100000 miles in 1 second and then back 100000 miles in 1 second. Shouldn't time experienced for Person A still be 2 seconds, even when compared to person B?
You are traveling to the future faster. If you went "faster" than light, you would be "outside" of time. Reaching the speed of light is like an asymptote, a speed that you can only get infinity closer to but never reach. At least with our current understanding.
>>12579070An intuitive way of understanding why this happens is to imagine a cyclotron moving linearly along its rotation symmetry axis, while also spinning a particle in a closed circle.As the particle’s speed increases, the magnitude of its momentum vector may increase without bound, however, the magnitude of the velocity vector may not. Spinning the particle causes the momentum components in the rotation plane to dominate the linear axis component, so the momentum vector converges into the rotation plane. At the same time, the velocity vector must point in the same direction as the momentum vector, so it will also converge towards the rotation plane, but because the speed of the particle has a finite bound, the particle must lose some of its linear axis velocity component to gain some rotation plane velocity components.