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pallidin
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Does gravity propagate at the speed of light?
Originally posted by Erich Schoedl
I have an idea of a cheap way it could be done.
-In a vacuum tube, have two 1kg weights (for balance) on a small motor, and spin them really fast at a constant rotational speed.
-Then at given distances from the spinning weights, have very small masses suspended also in the tube.
-monitor the system over a long period of time (so the oscillations have time to stabilize). And use light of a fixed wavelength to measure the positions of the smaller masses at specific times.
The posistions of the small masses relative to the light should tell us something more than just the spring constant of the device used to fix them .
Originally posted by Erich Schoedl
You know, with all the fancy gadgets we are building to attempt to find gravity waves from outerspace, you wonder why we haven't devised an experiment to measure the speed of gravitational changes on the smaller scale.
Quantum theory does have non-locality, but it remains true that no signal can travel faster than light. So it is improbable that gravity waves travel faster than light. If you think about it, it is also absurd that they travel at a speed less than light: Imagine, the sun suddenly disappearing, and the Earth still traveling in its orbit even as we see the sun winking out!Originally posted by Erich Schoedl
Wouldn't it be interesting though, if we found out it traveled at 137.036 times light speed or something?
This is one reference to the experiment that I think you are referring to (there are many others):Originally posted by jimmy p
There was a report in a New Scientist magazine a while back (i can't remember which one) where apparently some scientist had used some data and equations, as you do, and worked out the speed of gravity. It is slightly slower than the speed of light, sorry to be unglamourous, but i don't know the exact figure, maybe someone with more patience and/or knowledge would care to fill in my blanks.
In fact, what Tron said above, is true though, if the sun burned out, then after 8 minutes it would be dark and cold, and a little time after that, the Earth would spin off into space...worrying thought that!
Originally posted by Gara
light takes 8.3 minutes to get from the sun to us. the planet does not get pulled to where the sun looks like it is. it gets pulled "ahead" of where it looks like. it gets pulled to where the sun looks like it will be, in 8.3 minutes time, where the sun ACUALLY is. there for, gravity is instant. but, its not. gravity doesn't acually move, it doesn't get from the sun to us where we are instantly, it just didnt HAVE to move. think about a solid pole. if you push one end, and the other end (1 AU away) would move at the same time.
LURCH said:But the very reason for that is because it will take the most sensitive equipment we have to detect the most powerfull gravity waves (like those theoretically produced by neutron stars in close orbit around one another).
The speed of gravity refers to how quickly gravitational force propagates or travels from one object to another. It is a fundamental concept in physics and is often compared to the speed of light.
According to Einstein's theory of general relativity, gravity does indeed move at the speed of light. This means that any changes in the gravitational force between two objects would be felt at the same rate as the speed of light.
Understanding the speed of gravity is crucial for our understanding of the universe and how it works. It helps us explain phenomena such as planetary orbits, gravitational waves, and the behavior of black holes.
Yes, the speed of gravity is considered to be constant in a vacuum. This means that it will always travel at the same speed, regardless of the distance between two objects or the strength of the gravitational force between them.
Yes, scientists have been able to measure the speed of gravity using various methods, including observing the timing of pulsars and studying the movement of binary star systems. These measurements have confirmed that the speed of gravity is indeed equal to the speed of light.