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Giving Thanks for the Speed of Light

‘…I think we should do better than just be grumpy about the finite speed of light. Like it or not, it’s an absolutely crucial part of the nature of reality. It didn’t have to be, in the sense of all possible worlds; the Newtonian universe is a relatively sensible set of laws of physics, in which there is no speed-of-light barrier at all.

That would be a very different world indeed. In Newton’s cosmos, when a planet moves around the Sun, its (admittedly feeble) gravitational field changes instantly throughout all of space. In principle, in pre-relativistic laws of physics it would be possible to imagine communication or transportation devices that took you from here to billions of light years away, in as short a time as you can imagine.That seems like fun, but think about what you’re giving up. The speed of light enforces what physicists think of as locality — what happens at one point in spacetime influences what happens nearby in spacetime, and those influences gradually spread out. A universe

That seems like fun, but think about what you’re giving up. The speed of light enforces what physicists think of as locality — what happens at one point in spacetime influences what happens nearby in spacetime, and those influences gradually spread out. A universe without the speed of light would be one that allowed for non-local influences; one where different parts of space weren’t safely separated from one another, but were potentially connected in dramatic ways. That would be convenient for some purposes — but so utterly different from the real world that it’s hard to think through all of the consequences consistently…’

Source: Sean Carroll, Preposterous Universe