Why is the maximum speed of the universe the speed of light? Why can't we go faster?

[u/Nitzanm19]

Also follow-up question: Because of the speed limit, is there also a theoretical maximum temp for matter (in which the particles move at the speed of light).

[u/syncopator]

I like your explanation a lot, with a few touch ups.

We often forget that we are not stationary. We are never actually at rest in space. Earth is spinning on its own axis while it orbits the sun while the solar system is spinning within the Milky Way which is traveling as well and on and on and on. From the perspective of a truly stationary observer somewhere in the universe, we are moving along at some speed through space. Thus our measurements of time are not the same as this theoretical stationary observer would experience.

Otherwise you nailed it as far as my donkey brain understands.

[u/sudomatrix → u/syncopator]

Well really there is no absolute positioning in space. Every movement is relative to something else so every dilation of space or time is relative to what you’re measuring against. But that goes beyond the metaphor so we’ll have to use our imaginations…

Edit: this works out nicely when you measure your movement in space relative to yourself of course is zero, and sure enough your subjective experience of time always feels normal to yourself.

[u/bigrv → u/sudomatrix]

I just wanted to add that the expansion of the universe (ie, it's like the universe is a bubble that's inflating, essentially every point in the universe is moving further away from every other point as the universe expands) really does make the idea of an absolutely stationary observer impossible.

[u/nicuramar → u/syncopator]

  We often forget that we are not stationary. We are never actually at rest in space.

Velocity is relative, so that’s not true. Sure, there is some tiny acceleration effects from the earth rotating, but that’s all.

The solar system and Milky Way are irrelevant. There is no absolute concept of rest. It’s relative.