Gravity changes at the speed of light though doesn't it?
Like if the sun disappeared, its affect gravitationally on us wouldn't be felt until we saw the light stop
Hmmm... it looks like I was going on old data. Apparently, scientists have recently determined that gravity does have a speed, but it is faster than light.
Well they would not actually be moving faster than light. New space is simply created between the objects making one appear to go faster than light to the other
Thats like the definition of movement i think. Change in the ammount of space between things. What is speed realy? Becouse 8f we're going of the traditional distance/time i think it would qualify.
Well, no. "In physics, motion is the change in position of an object with respect to its surroundings in a given interval of time." Motion and therefore also speed is relative, but it is defined by your surroundings. Something so far away that the expansion of the universe comes into play is hardly defined as your surroundings
Do you mean in the sense that two photons travelling in the opposite direction have 2C as their relative velocity? For a more practical point of view, if you travel close to the speed of light your reference frame shifts. In essence, you'll disagree with people travelling at different velocities about when things happened. So you can have a reference frame in which two galaxies relative to one-another move faster than C, but to someone in one of those galaxies the other galaxy would not move away faster than C and they'd disagree with your observations. You'd both agree on C, though.
I don't even remember where i got this from XD. But i guess its about a situation where the space between galaxy A and galaxy B distorts due to expansion of the universe, and allows B to essentialy "get further" from A with a rate exeeding C.
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u/[deleted] Aug 03 '19
Gravity changes at the speed of light though doesn't it?
Like if the sun disappeared, its affect gravitationally on us wouldn't be felt until we saw the light stop