Guest Guest_Dr.Brain Posted February 6, 2003 #1 Share Posted February 6, 2003 Hey u all... just thinkin'....what causes Gravity? Link to comment Share on other sites More sharing options...
j6p Posted February 6, 2003 #2 Share Posted February 6, 2003 I would guess, mass warping space Link to comment Share on other sites More sharing options...
Bizarro Posted February 6, 2003 #3 Share Posted February 6, 2003 i would say that it has something to do with the acceleration of the earth and also its mass Link to comment Share on other sites More sharing options...
Saru Posted February 6, 2003 #4 Share Posted February 6, 2003 I would guess, mass warping space I think that just about sums it up. Link to comment Share on other sites More sharing options...
Homer Posted February 6, 2003 #5 Share Posted February 6, 2003 I would guess, mass warping space Mass warping space is gravity, but what causes space to be warped by mass? How does a body of mass warp space to create gravity? I have no idea myself. Link to comment Share on other sites More sharing options...
Bizarro Posted February 6, 2003 #6 Share Posted February 6, 2003 f=ma Link to comment Share on other sites More sharing options...
Homer Posted February 6, 2003 #7 Share Posted February 6, 2003 How does F=ma have anything to do with it? Link to comment Share on other sites More sharing options...
Halo_Jones Posted February 6, 2003 #8 Share Posted February 6, 2003 I have no idea what causes gravity.But Hey Dr Brain nice to hear from you again, I'v missed your entertaining posts. Link to comment Share on other sites More sharing options...
Saru Posted February 6, 2003 #9 Share Posted February 6, 2003 i would say that it has something to do with the acceleration of the earth and also its mass Dschwartz, I'd have to disagree with the idea that gravity is caused by the acceleration of the earth - it's the mass of the earth itself that warps space. I'd also have to agree with Homer in that f=ma is of little relevance here, it certainly doesn't help explain what causes gravity. Link to comment Share on other sites More sharing options...
kermit Posted February 16, 2003 #10 Share Posted February 16, 2003 Is gravity immediate or does it have a speed? And if it has a speed, how fast is it? How could it be measured? hmmm so many questions hehehe Link to comment Share on other sites More sharing options...
Homer Posted February 17, 2003 #11 Share Posted February 17, 2003 Maybe SaRuMaN may know the latest. There was a recent report that stated gravity was measured at the speed of light. Then, just a few days later, another report said the first report was wrong. I believe it's inconclusive at this time. Obviously, if gravity is not immediate, then it has speed. Does anyone else know if it has been determined one way or another yet? Link to comment Share on other sites More sharing options...
j6p Posted February 17, 2003 #12 Share Posted February 17, 2003 I think they are trying to measure the speed of something that isn't able to be measured. I would compare it to trying to measure the speed of a 7. I have a bet with a friend that they will never find the "graviton" because there isn't a such thing. I hope I don't loose, mooning is so undignified. Link to comment Share on other sites More sharing options...
Homer Posted February 17, 2003 #13 Share Posted February 17, 2003 Thats a strange bet jp6, So are you suggesting that gravity has no speed, or just that it has speed but it can't be measured? If you're saying it has no speed, than are you also saying that gravity is immediate? Link to comment Share on other sites More sharing options...
Kismit Posted February 17, 2003 #14 Share Posted February 17, 2003 I know this is definately not my area of expertease (like spelling ) but didn't we have a News Diacoveries thread earlier that sugested that the Earths gravity was affected by all the planets in our solar system . Wouldn't this make it very difficult to measure the speed of gravity as it would be constantly changing? Link to comment Share on other sites More sharing options...
Bizarro Posted February 17, 2003 #15 Share Posted February 17, 2003 well, explain how they create artificial gravity in space by rotating the ship then... f=ma that is gravity. the earth's gravity is a constant 9.81m/s squared because the earth has a constant speed of rotation and a constant mass of some number im too lazy to look up or calculate. mass cannot warp space, if that were so, we would warp the space around our bodies and have a gravity of our own. the earth's mass is huge, but its the rotation of that mass(and possibly the rotating parts of it... crust and mantle around the core) that creates our gravity. Link to comment Share on other sites More sharing options...
Saru Posted February 17, 2003 #16 Share Posted February 17, 2003 Homer & Kermit, I'm not sure what the current take is on the gravitational 'Instant action at a distance' idea, but I think the current speed of Gravity is regarded as being that of light. I don't think Gravity is instant, so I would agree that there must be a 'Speed of Gravity' one way or the other. DSchwartz, mass cannot warp space, if that were so, we would warp the space around our bodies and have a gravity of our own We do indeed warp space around our bodies, and we do have gravity of our own. The only difference is, a human being has an extremely small mass, and therefore has a correspondingly small gravitational pull - so small that it is generally unnoticable. The same goes for every single object on the planet. Mountains have a larger gravitational pull, a postage stamp would have a much smaller effect still. The earth on the other hand, is a very large mass, and has a correspondingly larger and very noticeable gravitational pull. Link to comment Share on other sites More sharing options...
Saru Posted February 17, 2003 #17 Share Posted February 17, 2003 Regarding your query about the rotating space station - the rotation on an orbitting space station creates 'artifical gravity', which is not really 'gravity' at all. The rotation results in an outward centrifugal force, which creates a similar effect that seems very much like the gravitational pull on the earth. It is not caused by mass warping space, but simply by the rotation causing the astronauts to experience a force pulling them towards the outer walls of the station. Link to comment Share on other sites More sharing options...
Bizarro Posted February 18, 2003 #18 Share Posted February 18, 2003 i am just not following your 'mass warping space' idea. it doesn't work according to the physics we have, so i still vote for the classical newtonian explanation. exactly how do you know that mass warps space around it? because Einstein says so? you saying that i am wrong is like me saying there is a god and you saying there isnt- its just speculation. Link to comment Share on other sites More sharing options...
Saru Posted February 18, 2003 #19 Share Posted February 18, 2003 The 'Mass warping space' theory does work according to present day physics, hence the fact that it is generally regarded to be correct. You cannot directly 'measure' the warping of space, granted, but the effects are very evident. so i still vote for the classical newtonian explanation There is no newtonian explanation for gravity at all, Isaac Newton could not explain gravity, he simply observed it. He observed it's effects, but could not explain why it was there. There have been numerous experiments carried out to prove the accuracy of General Relativity. One such experiment involved the bending of light when it passed through a sufficiently strong 'gravitational field'. This was carried in the early 20th century, when light from the planet Mercury was found to bend small amounts due to the gravitational field of the sun. This, and many other experiments since, prove the accuracy of General Relativity beyond reasonable doubt - not simply because 'Einstein says so', but because it is correct. Link to comment Share on other sites More sharing options...
Althalus Posted February 18, 2003 #20 Share Posted February 18, 2003 Below are a coup[le of links to sites that essentially back-up the mass-warping-space theory: Relativity - General Theory Click here Link to comment Share on other sites More sharing options...
Bizarro Posted February 18, 2003 #21 Share Posted February 18, 2003 what you call warping, i call the reaction to a force being applied. if you think that force acting on light will not draw it towards the force, then you are crazy. gravity is a force and when you move something against that force, it is going to affect its trajectory- this is not necessarily warping space. einstein explains this as warping space but others explain it as the effects of a force on an object. that's why i say i believe newton's ideas on gravity. i love how people take simple things and try to 'bend' them to their philosophies just because something is 'generally regarded to be correct' doesn't give you the right to shoot down my opinion. ill stick with my last statement. Link to comment Share on other sites More sharing options...
j6p Posted February 18, 2003 #22 Share Posted February 18, 2003 Good morning Althalus, I've added those links to my vast bank of great links thank you. I've taken this excerpt from one link because it explains the lensing effect(bending of light due to a gravitational influence): During a total solar eclipse bright stars are visible on photographs of the darkened sky around the eclipsed Sun. Another photograph of the same area of the sky can be made at night (a few months earlier or later) with the same telescope when the Sun is in a different place in the sky. Star positions on the two photographs can then be compared and will show that the stars around the eclipsed Sun have shifted away from the Sun. The amount of deflection decreases with the star's distance from the Sun's limb. This experiment was carried out for the May 29, 1919, total eclipse by two teams of British scientists, one lead by Arthur Eddington. Their results and numerous measurements since all support the predictions of Einstein's general relativity and confirms the existence of a region of curved space surrounding the Sun. In science as in most things if the outcome of an action is predicted with near exact accuracy, its almost a sure bet that the person making the prediction knows what he/she is talking about. Link to comment Share on other sites More sharing options...
Saru Posted February 18, 2003 #23 Share Posted February 18, 2003 If you think that force acting on light will not draw it towards the force, then you are crazy. DSchwartz, Try applying a magnetic force on a beam of light, and see if that will cause it to bend. Light will only bend when passed through a gravitational field - a curved region of space. If the rotation of a body causes gravity, then why do non-rotating bodies exhibit a gravitational pull ? In addition, if the rotation of the earth was the only thing that caused it's gravity, then everything on the surface would have been flung off into space. I'm not sure you're really putting forward an arguement against 'mass warping space', what your saying is that gravity is the force attracting all bodies towards each other, which is true, but that doesn't prove or disprove the warping of space idea, which tries to explain what causes these gravitational forces in the first place. Link to comment Share on other sites More sharing options...
Bizarro Posted February 18, 2003 #24 Share Posted February 18, 2003 im not trying to prove or disprove anything. quite honestly, i couldn't begin to believe that i have an explanation of gravity. i think it will be millenia before mankind can grasp the truth about such things. we just don't have enough experience with space to formulate this kind of knowledge yet. Link to comment Share on other sites More sharing options...
Homer Posted February 18, 2003 #25 Share Posted February 18, 2003 DS, You’re right in that mankind still has much to learn about gravity. Although it is known that gravity doesn’t actually push or pull anything, and instead is the result of mass warping space, nobody knows why it has the effect on space that it does. Link to comment Share on other sites More sharing options...
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