ELIF: how is time relative?
In: Physics
This will be hard if you are 5 but there is a simple thought experiment, one that PBS Spacetime did on the topic. Say you are sitting on a photon clock, and your buddy is sitting on a photon clock facing you. The photon clock is a photon that bounces between two mirrors that you happen to be sitting on. They are bouncing away, as long as you and your friend are going at the same speed, these clocks will appear to be in sync. Say you shove your buddy a bit ahead if you, his clock will appear to slow down. That photon isn’t just moving up and down, it is also moving in the same direction you are going. So the closer you get to the constant C (186,282 miles a second) the longer that photon will appear to take bouncing between the mirrors. Except, if that is the clock you are sitting on time appears to be the same as it ever was. Once you hit C then the photon will not longer bounce, you have traded all the ‘time’ for speed. At C there is no time, everything is *right now*.
Interestingly, the opposite happens (all time, no speed) at the event horizon of a black hole. We have no real human experience to relate this too, which is why it is so hard for a 5 year old to understand. We are dealing with very abstract concepts that require us to take perspective of multiple different points of reference at differing velocities. That is why it took hundreds of years between Newton and Einstein, not that relativity wasn’t an unknown concept to people, but it is so mind-bending that it took another seminal genius to sort it out.
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