I’ve heard of a light cone, but never heard the term gravity cone. Seems to me a light cone is kind of misnamed or arbitrary. It’s more like an information cone. There’s nothing special about light. You just can’t feel things that happen outside the light cone. So if a big object moves outside your light/gravity cone, you’ll never feel the gravity wave. Should it just be thought of as a gravity cone? Or a causality cone? Or an information cone?
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Am I misunderstanding this concept?
In: 10
As you noticed, there are many things moving at c: gravity, light in vacuum, more generally an electro-magnetic field, information, causality, …; and absolutely everything is (locally) bounded by c, nothing can exceed it.
Ultimately, pick whatever name you prefer for yourself. But in communication with other people, it is better to use established names, in this case “the speed of light (in vacuum)”. However:
> causality cone
This one probably is closest to the truth, as it is the most general.
One should now probably talk about entanglement, local realism, and a bunch of other things that sound like they either violate causality and/or are faster than c, but this probably leads to so many other things… anyway, there are already some ELI5 on those.
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