us.2u Posted March 29, 2005 Share Posted March 29, 2005 Please answer the following question only if you are sure of the answer 'What is the speed of gravity in miles per second?...us.2u Link to comment Share on other sites More sharing options...
Primarygun Posted March 29, 2005 Share Posted March 29, 2005 I watched "the elegant of universe". It told me that speed of gravity is the same as the speed of light in vacuum. I think it was proved by Einstein. Link to comment Share on other sites More sharing options...
us.2u Posted March 29, 2005 Author Share Posted March 29, 2005 I don't find this answer decisive why mention 'vacuum?' Is the speed of light & gravity variable?...I don't know...us.2u Link to comment Share on other sites More sharing options...
Primarygun Posted March 29, 2005 Share Posted March 29, 2005 Speed of gravity should be equivalent to the speed of a light ray in vacuum. Link to comment Share on other sites More sharing options...
us.2u Posted March 29, 2005 Author Share Posted March 29, 2005 Yes, but what is the speed of gravity ouside of a vacuum? & if it is the same or faster how do rockets fly through it's force? also is the speed of gravity & or light the same throughout the universe black-holes included (Not concealed in vacuums)...us.2u Link to comment Share on other sites More sharing options...
swansont Posted March 29, 2005 Share Posted March 29, 2005 According to general relativity, gravity travels at c, which is the speed of light in a vacuum. The speed of light in a medium (index of refraction >1) is c/n, which why sometimes you say "in a vacuum," where the index is 1. Link to comment Share on other sites More sharing options...
us.2u Posted March 29, 2005 Author Share Posted March 29, 2005 According to general relativity, gravity travels at c, which is the speed of light in a vacuum. The speed of light in a medium (index of refraction >1) is c/n, which why sometimes you say "in a vacuum," where the index is 1. But does gravity have a speed outside of a vacuum if so can we measure it?...us.2u H e l p Link to comment Share on other sites More sharing options...
swansont Posted March 29, 2005 Share Posted March 29, 2005 GRAVITY TRAVELS AT C What part if that is problematic? Nobody said anything about the speed of gravity in a vacuum or not in a vacuum Link to comment Share on other sites More sharing options...
Ophiolite Posted March 29, 2005 Share Posted March 29, 2005 us.2u, the speed of gravity equals the speed of light in a vacuum regardless of which medium the gravity is acting through. At least that's what I understand swansont to be saying. Link to comment Share on other sites More sharing options...
us.2u Posted March 29, 2005 Author Share Posted March 29, 2005 Yes I'm aware of Newtonians law & his formula F= Gm1,Gm2 over D2 where G=gravitational constant & also realise the forces of attraction are necessary to keep the planets moving in their curved paths around the sun. And without this force they would move straight out into space...also the required force I realise is by the suns own gravity which I presume pulls the planets towards it but the combination of the planets forward motion & motion under their gravity must keep them in orbit around the sun...yeah? Now is this gravity uniform throughout the universe? can we measure it if so how & what would be the correct equation? phew I feel like giving up am I dense? ...us.2u Link to comment Share on other sites More sharing options...
mustang292 Posted March 29, 2005 Share Posted March 29, 2005 Here us.2u, try this site, I hope it helps you.---> http://www.ldolphin.org/vanFlandern/gravityspeed.html Link to comment Share on other sites More sharing options...
Ophiolite Posted March 29, 2005 Share Posted March 29, 2005 Two points: 1. I'm not exactly clear at each instance what you are asking, so the answers may miss the mark. 2. You note that you are aware of Newton's formula, but I want you to really think about what it says, for I think the answers to your last couple of questions are there. It is called the Gravitational Constant for a reason - it is constant, throughout space-time: everywhere and everywhen. (Let's not confuse the issue with the speculations that it might vary over great distances and could have varied over time. Mainstream thought says it's constant.) If you don't exert a force on an object it just sits there, or keeps moving in the same direction at the same velocity. You are correct that for planets this straight line is transformed into a curve as gravity accelerates the planet. The correct equation for the specific force is the one you have already given i.e. the force depends upon the masses of the two objects that are attracting each other, their distance apart and G. Does that help? Link to comment Share on other sites More sharing options...
swansont Posted March 29, 2005 Share Posted March 29, 2005 Yes I'm aware of Newtonians law & his formula F= Gm1,Gm2 over D2 where G=gravitational constant & also realise the forces of attraction are necessary to keep the planets moving in their curved paths around the sun. And without this force they would move straight out into space...also the required force I realise is by the suns own gravity which I presume pulls the planets towards it but the combination of the planets forward motion & motion under their gravity must keep them in orbit around the sun...yeah? Now is this gravity uniform throughout the universe? can we measure it if so how & what would be the correct equation? phew I feel like giving up am I dense? ...us.2u You do realize that these are different questions than what you asked earlier, right? GMm/r2 is approximately correct. General relativity gives a better answer, but is far more complicated. Gravity isn't uniform in the sense that it changes with r. Yes, you can measure it, because of the orbital laws that are in place let you take orbital observations and deduce the behavior of whatever it is you are looking at. The problem is that it appears that either the equation is not completely correct, that there is some other force in play, that there is mass that we can't observe, or some combination of all this, because the observed motion of some things in the cosmos doesn't follow what we expect. There are pros and cons that go along with all of these. Astronomers are still looking into it. Link to comment Share on other sites More sharing options...
swansont Posted March 29, 2005 Share Posted March 29, 2005 Here us.2u, try this site, I hope it helps you.---> [url']http://www.ldolphin.org/vanFlandern/gravityspeed.html[/url] It's not real physics, so I don't see how it can be helpful. It's like sending someone who wants to learn about thermodynamics to a perpetual motion website. Link to comment Share on other sites More sharing options...
mustang292 Posted March 29, 2005 Share Posted March 29, 2005 Posted by U2: But does gravity have a speed outside of a vacuum Well this is the question he has asked over again, and noone has addressed it. Posted by swansont: It's not real physics, so I don't see how it can be helpful. It's like sending someone who wants to learn about thermodynamics to a perpetual motion website. Okay, I said I hope it helps. If not fine. But would you then stop jumping around his question and answer it smarty? Link to comment Share on other sites More sharing options...
blike Posted March 29, 2005 Share Posted March 29, 2005 But would you then stop jumping around his question and answer it smarty?HE DID. "GRAVITY TRAVELS AT C"; C is the speed of light in a vacuum. Thread closed. The answer is in here, if you can't find it, we can't help you. Link to comment Share on other sites More sharing options...
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