# Graviton Properties, best guesses?

1. Mar 19, 2006

### Chaos' lil bro Order

Hey,

Do physicists have any idea about any of the theorized 'graviton's' properties?

spin
charge
rest mass
wave length
anything?

As far I know (which is very little) the only thing we know is Gravity's strength relative to the other 3 forces.

P.S. Why was LISA's three arms set at 5 million km apart? Surely this must have been based on some expected value for probability of detection? Otherwise, why not set them 1 million km apart.

Last edited: Mar 19, 2006
2. Mar 19, 2006

### arivero

spin 2. It can be argued from tensorial properties, and also because odd spin forces are repulsive between equal charges.

Also it can be argued that a closed string has spin two because two open strings have spin one each :rofl:

3. Mar 19, 2006

### Janus

Staff Emeritus
Spin: As mentioned, 2
Charge : 0
Rest mass: 0
Wavelength: dependent on its frequency.

4. Mar 19, 2006

### Chaos' lil bro Order

1) So gravity is theorized to be a sinusoidal wave like EM then?

2) Why charge = 0, because we observe that it doesn't interact with electrons, protons and other charged particle?

3) How was spin = 2 derived, any papers you know of that I can read?

Thanks a bunch.

5. Mar 19, 2006

### Creator

The distance is to optimize detection of GW frequencies below 1 millihertz (.001 hertz).

Creator

-Lottery: The government"s way of taxing the mathematically challenged.-

6. Mar 19, 2006

### Creator

Not exactly, Chaos.
EM wave is dipolar. GR predicts the lowest order radiation of GW's to be quadrupolar based on the necessity of a changing quadrupole mass source. (Gravity itself is not a wave, but a changing quadrupole mass moment is expected to produce a gravity wave).

Creator

Last edited: Mar 19, 2006
7. Mar 20, 2006

### Janus

Staff Emeritus
Gravitational radiation is, but not gravity itself.

The graviton serves the same role for gravitation as the photon does for electromagnetism.

In electromagnetism you have a field which manifests itself as an attraction/repulsion between charges, and a radiation which manifests itself as radio waves/light( which can also be thought of as "ripples" in the field).

The photon is a unit of that radiation which, due to QM, has some particle-like properties).

Also in QM, you can have virtual particles, these are particles that appear out of nowhere by virtue of "borrowed" energy and then vanish giving up this energy before they can be detected.

The electromagnetic field is maintained by these virtual particles, in this case, virtual photons. It is these virtual photons that are the method by which the field exchanges force between the attracting/repeling charges.

For gravity, just insert gravitational field, gravitational radiation and graviton into the appropiate spots above.

Gravitons are the units of gravitational raditation and virtual gravitons are the exchange particle for gravity.

Of course there are differences between the two interactions, as noted by Creator.

8. Mar 24, 2006

### Ratzinger

But the ripples through this field, i.e. EM waves, are made of real photons.
Real photons are no force carriers.
But they (of course) transmit energy between matter.
They are created when charges accelerate and if bound systems decay.

Are these four remarks correct? Would someone like to add something?