alt Hacker NewsThis was perhaps my favorite part of Physics 390 ("modern physics") which was about quantum dynamics and relativity. The speed of light is defined in terms of a velocity (~300,000,000 m/s) but if you were traveling at the speed of light time stops (which keeps the rule that its constant in all frames of reference). That and time passes more quickly at higher altitudes and these days we can actually measure that. Wild stuff.
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> but if you were traveling at the speed of light, time stops
Are we saying then that it is theoretically possible that (a) photons have a zero or near-zero lifetime, but that also (in our frame of reference) (b) they exist for a finite duration of time and are visible during that time simply because time stops for them ? Or did someone manage to slow down light to some fraction of light speed ?
Also see the twin paradox, which is related to this and equally fascinating.
If one twin stays on earth and the other makes an intergalactic trip (with the speed of light), upon return, the one on earth will have aged much more than the one on the trip.
My favorite explanation: https://www.youtube.com/watch?v=Vitf8YaVXhc
The fact that at speed of light time stops is just so bonkers to me.
A photon is, from its point of reference, at the point of creation and at the point of destination at the same "time". Its literally seeing both parts of the universe at the same time, and since its traveled some distance over that time it cannot perceive, its essentially connecting 2 points in spacetime.
If I understand it correctly, every photon exists, from its point of view, for only infinitely small amount of time (similar to how virtual particles do exist from our point of reference), but for us its so easy to "play" with the photon along its path, giving us plenty of time to even decide what we want to do with it after it has already been created.
Its just so bonkers that time can be perceived such differently depending on frame of reference.