Why would'nt this work?
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Neither do the two gravity wells the stick spans. And the earth and moon are moving relative to each other, someone would probably get their head knocked off by that stick. Before it eventually falls to the earth with quite a bit of force because earth's gravity well will win. Then it'll eventually settle into a giant teeter totter, assuming it is rigid enough to survive the impact.
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Putting it on the moon is just a distraction. It doesn't matter if the rod is 1m long or 100,000km.
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because...
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Alas, the longer the stick is, the floppier it gets.
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I don't get it. Care to explain?
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That'll anger the universe's devs who will then bully you.
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I'm not sure.
The beam of light would bend as it travels to the moon, delaying the projected dot on the moons surface. -
Sure, the time between detections is faster than the time it takes light to travel from one detector to the other. Nothing is actually traveling faster than light and no physical laws are broken.
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this isn't at all what this example depicts, here there is actual information transfer.
this depiction is actually just false, the light would send information faster than the stick, because in the stick information only travels as fast as speed of sound in the stick, which is why completely rigid objects don't exist
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I don't think gravitational waves traveling at the speed of light is the same as the gravitational attraction being apparently felt faster than light travels. Similarly, electric attraction between + and - charges is different from electromagnetic waves being transmitted in the field. It's not light that is "communicating" that attraction.
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The compression on the end of the stick wouldn't travel faster than the speed of sound in the stick making it MUCH slower than light.
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You're forgetting the speed at which the shockwave from the compression travels through the stick. I guess it's around the speed of sound in that material, which might be ~2 km/s
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What about the speed of the earth's rotation though, could that fuck up the stick holding?
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You'd still be limited by light speed to transmit the information between the two locations to compare times or indicate they received a signal.
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It'll knock the moon and earth out of orbit!
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But.. But.. The stick is unfoldable!
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I don't think gravitational waves traveling at the speed of light is the same as the gravitational attraction being apparently felt faster than light travels.
I don’t know how you would measure gravitational waves without measuring gravitational attraction.
It's not light that is "communicating" that attraction.
Nobody said it was. The “speed of light” isn’t about “light”. Gravity propagates at the same speed, aka “c.”
This Reddit discussion on r/AskPhysics might help clear up your misconceptions. Notably:
Just to clarify: when people talk about the speed of gravity, they mean the speed at which changes propagate. It's the answer to questions like: if I take the Sun and wiggle it around, how long does it take for the Earth to feel the varitation in the force of gravity? And the answer is that changes in gravity travel at the speed of light.
But that's not what you're asking about. Whenever you're close to the Earth, gravity is always acting on you: it's not waiting until you step off a cliff, like in the Coyote and the Roadrunner. The very instant your foot is no longer on the ground, gravity will start to move it downwards. The only detail is that it takes some time for it to build up an appreciable speed, and this is what allows us to do stuff like jump over pits: if you're fast enough, gravity won't be able to accelerate you enough - but gravity is still there.
I get the sense that you’re thinking about the second scenario when objecting to the concept that gravity travels at the speed of light.
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