Why the graviton?

[heyo]

I was perfectly happy with the "bowling-ball-on-the-mattress" model for gravity. I see gravity as merely the warping of space around an object with mass.<br /><br />Why then do we need a graviton particle? That messes up my whole gig. I know that string theory predicts the graviton particle, how so? And why does string theory say that this never-seen particle must be the particle that transmits gravitational force?<br /><br />Futhermore, how is it that the exchange of particles can be attractive in the first place? Example: The way that quarks exchange gluons within a proton or neutron and that hold them together, seems to me that emitted particles would always be repulsive. Hmm.<br /><br />Maybe it's past my bed time...<br /><br />Heyo

 

[siarad]

The problem with the 'bowling ball' is, then what causes anything to follow the curve, gravitons maybe?

 

[tom_hobbes]

Couldn't the 'slope' exist as a property of other spatial dimensions we can't see? It doesn't explain much I guess, it would all be down to how the dimensions interact. (Talking shiite as ever.) <div class="Discussion_UserSignature"> <p><font size="2" color="#339966"> I wish I could remember<br /> But my selective memory<br /> Won't let me</font><font size="2" color="#99cc00"> </font><font size="3" color="#339966"><font size="2">- </font></font><font size="1" color="#339966">Mark Oliver Everett</font></p><p> </p> </div>

 

[nacnud]

In our time from BBC radio4 recently disscused the higgs boson and in doing so covered the other fundamental particles and what they all are. Try listening to the program (requires real player) for a good overview of the standard modle including the graviton.

 

[heyo]

Path of least resistance.... the object simply follows the curvature of spacetime. That's the way I always thought of it anyway.<br /><br />Heyo

 

[qzzq]

How does space-time 'know' when to curve? The graviton is just an explanation; a wave-particle that communicates gravity, probably a very, very minute ripple in the fabric of space-time itself, travelling at the speed of light. Since gravity is the weakest of the four fundamental forces in our Universe, the graviton is so small, it is currenltly beyond our capabilities to detect. <div class="Discussion_UserSignature"> <p> </p><p>***</p> </div>

 

[alkalin]

The description of the ‘warping’ of space is nothing more than a different label for the same idea as a ‘field’ effect. We talk almost always about the amounts of what force is versus ‘forces at a distance’, but do not have the slightest idea as to cause in any of the ‘fields’ of science. Sorry about the pun.<br /><br />I believe you are implying that a photon does not need a graviton for it’s particle or ‘field’ wave effect. Oh, wait, maybe the graviton is the photon in another dimension??? Nah, can’t be.<br />

 

[tom_hobbes]

If gravity 'propogates' at all, via gravitons or anything else then it does so faster than light. <div class="Discussion_UserSignature"> <p><font size="2" color="#339966"> I wish I could remember<br /> But my selective memory<br /> Won't let me</font><font size="2" color="#99cc00"> </font><font size="3" color="#339966"><font size="2">- </font></font><font size="1" color="#339966">Mark Oliver Everett</font></p><p> </p> </div>

 

[heyo]

<i>"If gravity 'propogates' at all, via gravitons or anything else then it does so faster than light. "</i><br /><br />Not so, as per an experiment/observation performed when Jupiter passed near a star in the sky, and the bending of the light was observed.<br /><br />I don't have the specifics of the experiment off hand, I will try and do some research and find it for you.<br /><br />Gravity propogates at exactly the speed of light, according to observation.<br /><br />Heyo

 

[siarad]

If gravity radiates then why does it pull & not push?<br />Forgetting all this bending of space, (just what is space) for gravity to pull I think it must be <i>crawling</i> outwards thus pulling <i>in</i> any particle, a simple reaction. <br />Neither explanation work for a black hole which gravity can't escape if restricted to speed of light.

 

[heyscottie]

The whole discussion about force carrying particles only "pushing" and not "pulling" uncovers some mistaken ways of thinking at this level.<br /><br />We shouldn't try to think of force particles as sort of momentum carriers that bounce off of distant objects, causing them to move away. It is more accurate to think of them as information carriers that give some information about a certain field strength in a certain direction, and cause the target to react by accelerating is some way relative to it.<br /><br />The graviton would simply be the information carrier for gravitational fields.<br /><br />As far as gravity moving at the speed of light, there is indeed serious doubt as to what that experiment was actually measuring -- the arguments are quite convoluted, but there are those who claim it was doing no more than measuring the speed of light, and finding that it travelled at (surprise) the speed of light.<br /><br />Gravitational waves probably *do* travel at the speed of light, but we cannot yet say for sure.<br /><br />Scott

 

[siarad]

Thanks but why is the information contained in gravity radiation the opposite of all other em radiation.<br />I've read about 'the pressure of radiation' & seen experimants showing the pressure of light, what about solar sails.<br />Does this mean gravity is not an em radiation although it seems the speed experiment was so assuming.

 

[heyo]

I don't think that gravity is any kind of radiation. It just doesn't square well with me. I have always learned to think of empty space not as a background stage upon which the universe plays itself out, but a flexible fabric that can bend and stretch and is an active participant in the cosmic symphony.<br /><br />I believe Einstein was right, that an object with mass bends spacetime around it creating a gravity well, so to speak, and an object within this gravity well will tend follow the path of least resistance which may mean acceleration towards the center of the spacial "depression".<br />

 

[heyscottie]

I think that most assume that gravity is NOT e-m radiation at all. If it was, that would mean that you could create light of a specific frequency, and you would have gravity. This is not the case.<br /><br />The light pressure on solar sails IS due to transfer of momentum -- a photon, while massless, does have momentum, and a reflection therefore causes the classic equal and opposite reaction, propelling solar sails.

 

[heyo]

If only we could figure out a way to generate gravity at will. I could envision engines which simply use some exotic form of energy to create gravity on one side of the ship, so the ship would "fall" forward and ride a gravity wave which moved along with it. You wouldn't need much gravity to keep accelerating gradually to a pretty good clip.<br /><br />Proxima Centauri here we come.<br /><br />Heyo

 

[bazukaz]

Well , my understanding of physics is incomplete,<br />but i think in this way:<br />1.Electromagnetic radiation takes energy,causing<br />the source to lose it.<br />The radiation of gravitons should take energy of the source,making it to lose mass and radiate less and less gravitons.<br />2.We can make a metal screen on a transformer to cancel its electromagnetic radiation.How can we do so with gravity??<br />What i mean that gravitons seem to pass through <br />Mass , interacting with it,and travel further.<br />3.The already stated argument about black holes.<br />The speed of the graviton should be infinite for <br />the black holes to emit them so to cause gravitation.<br /><br />Does that seem reasonable?<br /><br /><br />

 

[aetherius]

Can somebody tell me if this interpretation of gravity is the same as Einstein's sheet of space-time interpretation?---><br /><br />Matter, a planet, etc, exists in a sea of space-time rather than sitting on a sheet of space-time. <br /><br />Matter, a planet, etc, displaces space-time.<br /><br />Gravity results from the "push" created when the displaced space-time seeks to return to the area form which it was displaced.<br /><br />

 

[heyo]

I think the "sheet" is just the 2 dimentional graphic representation to show a 3 dimentional scenario in a way it's easy to visually interpret.<br /><br />Heyo

 

[justanotherone]

You just have to think of the way that Einstein described the 'warping' effect more as concentric spheres comming from the object, which can be described by Gauss Law, such that the closer to the object, the closer together the spheres and thus the stronger the force.

 

[bjdfit]

sorry, im new at this whole space-time thing. but, the graviton has never been measured, touched, seen? alone? it seems to me like gravitons are these invisible particles (or unparticles if they have no mass) that are attracted to anything with mass. and the larger the mass, the more gravitons are attracted to it. and since matter can neither be created nor destroyed, then how would gravitons? matter can be changed into energy. and energy travels in particles. so, why wouldnt gravitons follow energy too? light for instance, has gravity. so, (i dont know all about these models and theories or anything yet) if light were to be projected into infinity, wouldnt it take gravitons with it? so, the more light (and other energy) that is projected beyond a theoretical boundary of universal mass would mean more gravitons outside that boundary, meaning more gravitational expansional force away from the universe's "center". you cant see a photon or any other form of radiation from behind. it has to run into something and reflect back. so, wouldnt this whole "dark energy" jazz be simply "light energy" that we cannot see? (i dont know jack about dark energy either). and if this were the case, wouldnt the universe continue to accelerate its expansion because more and more gravitons are being projected into infinity, pulling the universe apart at a gradually faster rate? so, would the universe's expansion acceleration be faster at the outer rim of masses and energies, where there would be less radiation and less mass and so fewer gravitons but more gravitons escaping via radiation? and if a graviton is a unit of mass energy attraction, how would "it" travel faster than light? what would move a graviton faster than the speed of light if gravitons attract and don't repel? all the gravitons emitted from the universe are just attracting the universe to expand at an accellerating pace. you could call it "dark energy" because you sure cant see the radiation thats alw

 

[bjdfit]

why the singularity? <br /><br />what if two black holes collide? they would just create a larger black hole with multiple singularities, right? and add rotation to the black hole? <br />

 

[najab]

><i>what if two black holes collide? they would just create a larger black hole with multiple singularities, right?</i><p>I'm a little out of my depth here, but I seem to remember that the singularities would orbit each other in a decaying spiral until they collapse into a new sigularity with the mass of both of them.<p>><i> and add rotation to the black hole? </i><p>Yes, as they orbit each other there would be gravity waves created which would mimic a rotating black hole. Since we can't see past the event horizon, there would be no way for us to tell if it was a pair of orbiting singularities or a single one rotating.</p></p></p>

 

[aetherius]

How would a graviton form? Is it emitted from something or is it transformed from some other combination of energy/particle?