# Do gravitons exist?

1. Jun 27, 2012

### Wyzeguy

If a graviton existed wouldn't volume increase the effect of the gravity?

For instance light we know(I think this is pretty solid) is a particle. We can see evidence of this by say a solar sail. We increase the surface area that light can hit and the energy of light hitting the sail can be used to accelerate.

If gravity existed as a particle wouldn't it have more effect on stuff that has more volume?

ie We know that if you drop a feather and a paper clip in a vacuum at the same time they will hit at the same time. If gravitons existed wouldn't the feather drop faster because there were more particles effecting the speed at which it would accelerate?

2. Jun 27, 2012

### phinds

Since they DO drop at the same speed, you clearly have to be arguing that gravitons cannot possibly exist. They may or may not exist, but I don't think that argument has merit.

Last edited: Jun 27, 2012
3. Jun 27, 2012

### Wyzeguy

I am indeed arguing for the fact that gravitons do not exist.

By simply dismissing an augment without any counter argument is counter productive. It may also imply that it is not worth the time for a counter argument.

To me intuitively it makes a lot more sense that gravity is based upon a time and space that is warped by mass. If there were gravitons would it not take energy to create these gravitons?
How much energy does it take to move a mass like the moon enough to maintain an orbit? I would assume that the energy required would reduce the mass of the earth?

If the energy comes from the earth slowing its rotation then this would imply that if the earth didn't spin that the moon would not be able to orbit?

If the graviton existed would you not have to explain how it would be able exert a force on some of the volume of an object but not all of them equally in order to maintain a constant acceleration of objects of any size?

4. Jun 27, 2012

Counter argument:
If the gravitons are taking energy from earth, wouldn't other gravitons bring energy say from Sun and Moon and other celestial objects?

That said, the mechanism by which gravitons work is much more complicated than that. If my understanding is correct the gravitons do not propagate gravity they only propagate changes in gravity, like when object moves. Gravitational attraction of earth and moon does not require any particles it can be described by interaction with the field.

5. Jun 27, 2012

### ZapperZ

Staff Emeritus
What "gravitons" are you talking about? It appears that you've made up your own rules about this "graviton". It certainly isn't THE Standard Model graviton. So how are we expected to disprove the existence of YOUR graviton when the physics isn't established?

Zz.

6. Jun 27, 2012

### Wyzeguy

Wouldn't be an argument against gravitons?

In order to propagate changes in gravity, gravitons. would have to be able to move faster than the speed of light? Where a sense of the space time fabric warping might be able to move faster than light but no matter or fabric is moving faster than the speed of light. The ripple or wave may move faster but not the fabric itself.

7. Jun 27, 2012

### Wyzeguy

This may be the case... I am certainly no expert on this subject. If you could link me to a source that I could educate myself more on this subject I would appreciate it.

8. Jun 27, 2012

Why? Gravitons taking energy away and gravitons bringing energy. Net energy loss zero.

Gravitons move at the speed of light like all massless particles.

9. Jun 27, 2012

### ZapperZ

Staff Emeritus
Then may I suggest that before you declare or try to test whether something exists or not, you figure what WHAT that something is first! You need to be aware that you are coming into a forum that is full of physicists and experts in such fields, and it looks very foolish to make such an argument based on something you know nothing about.

I have no idea if you are aware of how complex the physics that you are trying to deal with. Here's an example:

http://arxiv.org/abs/gr-qc/0607045

Zz.

10. Jun 27, 2012

### DrSuage

for someone who knows naught about this subject j(ust finished 2nd year uk undergrad integrated masters in theoretical physics) its an interesting question. obviously the answer is that you've misinterpreted the way particles mediate force interactions as the others have been quick to note but I think that it would be nice if someone here did try to explain as best they could why your argument is incorrect instead of just telling you that its very complicated and being condescending. Isnt science about asking questions after all?

11. Jun 27, 2012

### ZapperZ

Staff Emeritus
Certainly. The CORRECT question in this case would be:

"Hi, what is gravitons? How does it interact to cause the emergence of gravity?"

It is NOT "Yes, I think this disproves the existence of gravitons, even though I have no idea what it is. So tell me what's wrong here?"

The latter is often the tactics of crackpots who don't want to learn. See #16 here:

http://insti.physics.sunysb.edu/~siegel/quack.html

Edit: BTW, you WILL note that I provided a reference for the OP to look at just so one gets a flavor of the physics involved.

Zz.

12. Jun 27, 2012

### DrSuage

Zz - get where you are coming from completely - there seem to be alot of threads in the relativity section asking about faster than light travel etc. However the OPs question did cause me to stop and think (as have many other "stupid" questions over the years such as twin paradox variants and the like).
would you mind giving a description to the relatively inexperienced physics student of how particles mediate force interactions in QFT and how the supposed Graviton would work within this framework? I have done a fair bit of non relativistic QM (up to dirac notation, spin 1/2 systems, formally, in my own time i learnt how to get to the Dirac Equation but im still confused by bits of it since i have yet to take that lecture course)
my knowledge of relativity is manifestly UNcovariant (lorentz transforms, energy momentum relation, no minowski space or 4 vectors unfortunately... thats coming next year...)

Thanks

13. Jun 27, 2012

### Bill_K

KGmphysdurham, Zz can answer for himself. But he's not the only one reading this thread, and I can tell you why I read the OP and did not answer. Because I could find no place to start. The question itself is about advanced physics, but the supporting argument involves basic physics - classical electromagnetism, classical mechanics, and quantum mechanics - and is fundamentally wrong throughout. And furthermore is based on the OP's "intuition". I felt there was nothing I could say that would be adequate. He needs to learn some physics first.
Do you understand the corresponding issues for photons? There have been innumerable threads on these topics, and the answers for gravitons are pretty similar.

14. Jun 29, 2012

### alemsalem

there are two effects associated with the photon, the solar sail thing absorbs "real photons" if you increase the surface area it absorbs more of these photons and the force would be stronger.
the other effect of photons is from "virtual photons" these mediate the interaction between charged particles and I think its a stretch of the imagination to think of them as real particles (unlike a real photon they can't keep moving forever without being absorbed)
now if you take a condensed amount of charge and you spread it into a larger volume that wouldn't mean that you have a larger force because it not like you already had a predetermined number of photons independent of who's there to absorb them.
for the same reason since you are not creating these photons it doesn't neccesarily take energy to move an electric charge (or the moon) in an orbit.

15. Jun 29, 2012

### Naty1

A general problem is that gravity is not included in the standard model of particle physics because it it not so well understood...neither classically nor via quantum mechanics.

no one knows; there is no experimental confirmation.

not necessarily. Does this imply you think a photon has 'volume'? If you are drawing an analogoy, what theory would that be based upon? Do you mean a graviton has mass?

Why do you think this is evidence of a particle?

There is no such theory.

In any case, a theory of quantum gravity would probably be required to fully understand gravitons.

If you are interested in learning more about gravitons, string theory offers some mind boggling and interesting clues: There, a graviton is a closed string in a low-energy vibrational state....a spin 2 'particle' so it does have some extraordinarily small 'volume'...but so does a photon via this mathematics. [The graviton particle was 'discovered by accident as a byproduct of the original theory.]

Some behavior of gravitons in string theory can be derived from 'AdS/CFT correspondence': Juan Maldacena I think was first to show a particular quantum theory without gravity is indistinguishable from another quantum theory that includes gravity but is formulated with one more space dimension. So this [incomplete] theory hints that gravity is related to the dimensions of spacetime. This view seems more difficult to reconcile to any 'volume'....

Last edited: Jun 29, 2012
16. Jun 29, 2012

### alemsalem

I think he is referring to radiation pressure on solar sails where you have more pressure with increased surface area.
of course he could tell you more about what he means, I'm just guessing :)

17. Jun 29, 2012

### Eimacman

Greetings ZapperZ

You said:

I believe that is right on the mark. I think that there is currently a 97% probability that gravitons exist. I also believe when we discover the true nature of gravitons, that it will be something simple practically under our nose. But that remains to be seen, perhaps finding the Higgs Boson may shed light on gravitons being that Higgs interactions tend to determine mass and possibly gravitation. If true that would be a mathematical nightmare.

Thanks for the reference.

Eimacman

18. Jul 27, 2012

### Spinalcold

LIGO has yet to find a gravity wave, I hope LISA will be able to (if funding isn't cut like it has been in north america for a lot of projects). I just think it's premature to think gravity fits into particle physics. The dream is unification, but there is no reason that a reductionist approach will work. It may take more complex theories and more computational power.

Gravity and the standard model are not unified, they may never be in a single formula; it may be a dynamic formula.

19. Jul 28, 2012

### Phantom13

I don't have much understanding of physics myself yet and I don't claim to. I'm only a sophomore in highschool, so please do not criticize me heavily if I say something you do not agree with. Rather than elaborate on all of your opinions I just have a few questions though. The first guy who created this thread, Wyzeguy, was claiming that a "graviton" would react in the same way as a photon by effecting something with more volume, because he thought that in theory, gravitons and photons are supposed to be similar particles. Just because the particles are similar though does not mean they would have similar properties or behave in the same way. We could say that gravitons are in a way a part of the Higgs field correct? Rather than interacting with volume, they interact with mass, and in a similar way that photons would have a greater force on something with larger volume like a solar sail, gravitons would have more effect on something with more mass. So if we were searching for a graviton, and gravitons are directly linked to mass, then how could we expect to find it before even discovering something like the Higgs boson? Like I said, I am uneducated and just want to ask a couple questions to anyone that would answer, so here they are. Is it possible that gravitons only exist and work in the Higgs field itself, in which case without discovering evidence of the Higgs field, how could we begin to hope for the graviton to pop up? Let us say that the graviton wasn't part of the Higgs field though, where would it be found? Another question I have is although things such as electrons, neutrinos, and other leptons have almost no mass, do we see signs of them exerting gravity? Also, when we do experiments with particle accelerators and are able sometimes to rarely see individual quarks, how do scientist determine their mass and can it be seen whether they are exerting gravity or not? My last questions is, we know that anything with mass has gravity because mass and gravity are linked, but if we can't yet measure gravity being exerted by individual quarks, then who's to say that the graviton is not linked to mass, but rather it is linked to individual quarks themselves and would be a particle similar to a gluon?