Posted on 02/11/2016 9:49:13 AM PST by jpsb
Scientists are claiming a stunning discovery in their quest to fully understand gravity.
(Excerpt) Read more at bbc.com ...
Albert Einstein 1, Isaac Newton 0.
Did they verify the speed or just detect the existence?
They say it matches equations, which implies the speed is verified, but it is not explicitly stated in the article that they verified that piece of it.
“General Relativity states that gravitation is not instantaneous.”
Oh yes it does. If it weren’t instantaneous, we wouldn’t be in stable orbits around the sun, because the drag from the moving gravitational source would have sent us all spinning off into deep space long ago.
yes
That's a little harsh don't you think?
Some among us are already spinning into deep space and don’t realize it.
Actually, yes. Nothing can take away from Newton's incalculable contributions to science and mathematics. All I should have said is that on the one point where Einstein's theory of relativity contradicted Newton's theory of universal gravitation, Einstein has been proven right.
The technology utilized in this cosmological search is nothing short of astounding.
Yes, entanglement seems to operate instantaneously.
Why or how... that’s a mystery still I think.
Nope; just too fast to measure.
Help me understand this. The earth is 8 light minutes from the sun. Is the gravitational effect of the sun on the earth measured by where the sun was 8 minutes ago or by right now?
Much better, I did not know that Newton even address the speed which gravity operated. I find that very interesting. I suppose not address the speed implies instantaneous.
It’s instantaneous. Our orbit is based on where the sun is right now, not where it was eight minutes ago.
Cool news. I have friends who worked on the LIGO project.
Can’t belieive the British are still calling it a black hole.
From Earth's frame of reference it's effectively instantaneous but if the Sun suddenly disappeared then Earth's orbit wouldn't change for 8 minutes. It would appear to be pulled to the point the Sun would have been in 8 minutes had it not disappeared. Is that incorrect?
No, you are correct, and I think you are really getting to the heart of what the difference is between the speed at which gravity propagates and the speed at which gravity waves propagate. Your example would be an example of gravity waves propagating, and not gravity propagating, which is why it would act at the speed of light.
It helps if you stop thinking about gravity itself and think about it as an effect of the geometry of spacetime. Mass warps spacetime, and gravity is the effect we feel as we travel through warped spacetime. Once the spacetime is warped, we feel these effects instantaneously, because they are produced by the geometry of the local spacetime we are traveling through, like the slope of the road you are driving your car over.
Now, if the sun were to disappear, spacetime would “unwarp”. That “unwarping” could not happen instantaneously. THAT is what would propagate at the speed of light, the “unwarping” of spacetime. Gravity, being an aftereffect of the local geometry of spacetime, is always going to be instantaneous, but the changes in that geometry can’t happen instantaneously.
Hey sweetheart, would you like to see my gravity wave machine?
“True but is not the communication between photons emitted from an excited electron instantaneous?”
Not sure, but a green photon from a traffic light and dude behind you honking is sometimes instantaneous.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.