Understanding Gravitons: A Key to Quantum Gravity?

[MarcusH]

Hello,

I am about as far from a physicist as physically possible, but I am fascinated by the theory, so I've re-enrolled in some intro physics classes next semester. (I'm a Poli Sci/Pre-Law Undergrad).

I've been reading a bit about the subject for some time now, and I'm a little confused regarding the Bosons that carry the force of gravity (gravitons?). I understand that photons carry radiation, W and Z bosons carry the weak bond and gluons carry the force that bind protons and neutrons to form nuclei. I am not quite grasping how gravity, the most evident force that exists, is not measurable by particles that carry the force of gravity.

Can anyone direct me to literature that will explain it, so that those of us non-grad students (yet!) can grasp the concept?

Thanks in advance,

Marcus Hodgkins

 

[AEM]

One of the places where you could get more information is Wikipedia. Search on the terms, Fermion, Boson, and Graviton. There you will find that bosons have integer spin, while fermions have half integer spin. Fermions are associated with mass, while bosons are associated with forces. Gravitons have spin 2, and are assumed to be massless. I'm sure you can connect the dots...

 

[arunma]

Hi Marcus. About gravitons, it's not that gravity has no carrier particle. It's just that we have, as of yet, been unable to detect the graviton. The theory exists, and we can even predict the spin. But doing experiments with gravity is very difficult. It's a very weak force, as evidenced by the fact that it takes an object the size of a planet just to create a noticeable gravitational force, whereas a small plastic rod with an electric charge can do the same thing. Experiments are underway right now to detect phenomena like gravitational waves, but have yet to gather any meaningful data (at least that's what my friend at LIGO tells me). All of this is actually related to the problem of formulating a quantum theory of gravity, in which the gravitational field is quantized like the other fundamental forces of nature.

If you dare, you might try Googling "quantum gravity," and see what you find. If I think of any books on the subject for laypeople, I'll be sure to send you a link too.