I know what the speed of light is basically the speed limit of everything in the universe, and no information can travel faster than light itself. Light also exhibits many interesting properties and also serves as a constant for many formulae and equations in physics. The space-time continuum changes depending on what fraction of the speed of light at which you are travelling.
However, why light? Why is light and only light the one “phenomenon” that dictates most of physics? What makes light so special? My apologies if the question is phrased kind of strange.
In: Physics
Another interesting way to think of it is to consider not just space, but “spacetime” – the four dimensions we all exist in (3 dimensions of space and one of time.)
Then we can say that everything and everyone – you, me, your cat, and the light around us, are all moving, all together, all at once, at the speed of light through “spacetime”. This “speed limit” is not just a “limit” but is the fixed speed at which everything moves through “spacetime”
Picture “spacetime” as “north and east” and you and I are standing together in an open field. we’re equally matched runners and start running as fast as we can – me due north and you due east. we are going the same speed but I am making progress moving only in the north direction, I don’t move at all to the east. You, the reverse, you make all your progress moving east but none to the north.
If instead I run, say, “northeast” then while we are going the same speed, this time some of my speed is to the north and some to the east. I’m moving to the east slower than you because some of my motion is also to the north.
We are running at a fixed speed “as fast as we can go” but making more or less progress in one direction vs the other depending on our direction.
So movement through “spacetime” is similar. There is only one “speed” anything and everything can move through spacetime. It’s not a range or a limit, it is one fixed speed. The “speed of light”
Some things, like light, see all their motion through space (“north”) and none through time (“east”). This is because photons have no mass. Heavier things that do have mass (like you and me), also moving through spacetime at the speed of light, have slower motion through space (“north”) because some of our motion (in fact most) is also through time (“east”).. the faster we can move through space, the slower we’ll move through time, and vice versa (just like the more we run north the less progress we make to the east)
Everything, everywhere, all at once is moving at the speed of light through spacetime. Light has no mass and so it only moves through space and doesn’t experience time. Anything with mass will have to split their motion at the speed of light between “space” and “time” and depending how fast you move in one of those directions, you necessarily end up moving slower through the other.
So what makes light so special? Nothing other than its being massless.
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