How fast does gravity travel???
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Einstein agrees, Gravity is not a force.
This video never fails to surprise me, bowling balls and feathers
This video never fails to surprise me, bowling balls and feathers
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First, many above are posting about the speed of light, which is completely different thing. All that about Edgington and rubber sheets is not for speed of gravity. Nothing to do with dark matter or energy either.
Gravity of course is a field, analogous to say a magnetic field, which doesn't have a property of speed.
One can talk about the speed of propagation of gravity.
Apparently not, the speed turns out to comply with lorentz invariance.
Space-time isn't curved, that's a myth, or rather an educational tool useful for those not happy with Hilbert space, Lagrangians, tensors, and that.
In QM you don't need curvature - you just do the maths and it works.
Gravity propagation speed is thought to be simply the speed of light. So far nobody has come up with a theory to modify that which looks reasonable.
It's been measured, and c still works within known errors.
Gravity of course is a field, analogous to say a magnetic field, which doesn't have a property of speed.
One can talk about the speed of propagation of gravity.
Apparently not, the speed turns out to comply with lorentz invariance.
Space-time isn't curved, that's a myth, or rather an educational tool useful for those not happy with Hilbert space, Lagrangians, tensors, and that.
In QM you don't need curvature - you just do the maths and it works.
Gravity propagation speed is thought to be simply the speed of light. So far nobody has come up with a theory to modify that which looks reasonable.
It's been measured, and c still works within known errors.
My posts relating to the bending of spacetime were in relation to Notches question about the gravitational pull on the earth #19 and ajohn explaining that demonstrating the bending of space time is 'tricky' #27 - both explanations were not to do with the speed of gravity and I didn't say they were
Yes, we should more correctly be stating the speed of the propogation of gravity, but I think most of us knew what we were talking about!
Yup, hence:
"c"*, but that doesn't really have much relevance to us mere mortals.
...it is very interesting for gravitational wave scientists though
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Hold on... Let me get this straight....
Your exceedingly confused chemistry teacher asked you about gravity?
No doubt your physics teacher was telling you all about covalent bonding too?
Your exceedingly confused chemistry teacher asked you about gravity?
No doubt your physics teacher was telling you all about covalent bonding too?
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This guy seems credible, though I'm not convinced about the "cool software"
The story isn't clear. Deliberately so probably as he's claiming to have inspired James Dyson.
The wiki even has a page on the speed of gravity
en.wikipedia.org
This page mentions Lambda. The aspect that comes and goes and gets changed
www.sciencenews.org
Down to astrophysics which tends to build ideas on other ideas. If one is wrong subsequent ones are. Fairly recently sums were found to not agree with what has been observed so along comes dark matter and even dark energy. This doesn't rule Einstein's ideas out but at some scale if the missing stuff can't be found there is a flaw. Some earlier people have always wondered about the reality of the expanding universe. These days it's fact and not worth studying further.
Speed of gravity - Wikipedia
This page mentions Lambda. The aspect that comes and goes and gets changed
Einstein's genius changed science's perception of gravity
Einstein struggled for years to solve the puzzle of general relativity. The pieces all fell into place in November 1915.
www.sciencenews.org
Down to astrophysics which tends to build ideas on other ideas. If one is wrong subsequent ones are. Fairly recently sums were found to not agree with what has been observed so along comes dark matter and even dark energy. This doesn't rule Einstein's ideas out but at some scale if the missing stuff can't be found there is a flaw. Some earlier people have always wondered about the reality of the expanding universe. These days it's fact and not worth studying further.
Gravity does not move.
What you see moving are objects that move because of gravity.
You observe the effect of gravity and think that gravity moves
Gravity is not made of mass, so it cannot move.
But an object with mass have effects on other objects and this is what you observe.
I'm afraid we are not looking at moving objects and assuming gravity moves.
We are looking at the speed of gravity, or to be slightly more accurate, the speed of propagation of a gravitational wave.
As you say:
We are talking about the effects observed by say an event that causes a massive gravitational disturbance in one part of the universe (say two black holes colliding); when will we, in a distant part of the universe be able to detect this event?
...and through measurements using experiments such as LIGO, these disturbances have been detected and the speed of the propagation of the gravitational waves has been determined to be "c"
Nobody really knows. All the current theories have a flaw in the maths and a unified theory has proven elusive. So it depends which theory you believe? Personally I like the theory that gravity is a wave that doesn't exist on its own. Being a wave it doesn't really move. The best description I've seen of this is imagine putting your fingernail in the thread of a screw. When you turn the screw your fingernail moves - but the screw does not. So gravity has no speed of its own.
The term gravity waves confuses things IMHO. They aren't waves they are disturbances in local gravity as measured here by us.
Gravity causes bodies to be attracted to each other. The sun moves due to the gravity effects from the earth. It's movement is tiny due to relative masses. Gravity fields extend some enormous distance so a massive event far away has an effect here.
Some of the gravity waves detected have been put down to black holes merging. They can't be seen so have to be inferred . This one could be seen but not that it was 2 neutron stars as far as I am aware anyway. This allowed light etc arrival to be compared with the gravity wave.
en.wikipedia.org
The reason for the use of the word wave is that the gravitational field changes and then settles to some other steady state.
Gravity causes bodies to be attracted to each other. The sun moves due to the gravity effects from the earth. It's movement is tiny due to relative masses. Gravity fields extend some enormous distance so a massive event far away has an effect here.
Some of the gravity waves detected have been put down to black holes merging. They can't be seen so have to be inferred . This one could be seen but not that it was 2 neutron stars as far as I am aware anyway. This allowed light etc arrival to be compared with the gravity wave.
GW170817 - Wikipedia
en.wikipedia.org
The reason for the use of the word wave is that the gravitational field changes and then settles to some other steady state.
That's not quite as catchy when you're doing public outreach, or trying to persuade funding bodies though!
Einstein's theories that can be proved to be true in what could be called locally say solar system distances. Once things get further and further away the same theories are used to explain what is detected - done that way they are bound to fit as it predicts them but they are predictions. We can't go and look. The Lambda kludge changes have had to be used as more info comes in. Then other things need to be discovered, dark matter and energy for instance. All to make the theory fit what is actually observed.
LOL This why some carry on looking for other ideas. Einstein is the best we have.
How do you weigh a planet or the sun. You can't so they are inferred in the form of ratios calculated from motions.
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