[syhprum (OP)]

This is a quote from the Scientific American article
The Search for a Unified Theory: A Pipe Dream? 

"The fundamental problem with detecting gravitons is the extremely weak nature of the gravitational force. To address this problem researchers have designed exceedingly sensitive equipment that should in principle be able to detect even discrete gravitons."

This is a ludicrous claim as the exceedingly sensitive equipment has not as yet detected the gravity waves from colliding black holes and Gravitons are postulated to be something like 10^-10 the mass of Neutrinos


[MOD EDIT - PLEASE FORMAT YOUR THREAD TITLES AS QUESTIONS, IN LINE WITH THE FORUM CONVENTION. THANKS.]

[dlorde]

Maybe the article has confused gravitons with gravity waves. As I understand it, gravitons have way too small an interaction with matter to make a detector practical, and any (unfeasibly unlikely) graviton interaction event would be swamped in the noise of neutrino interactions (themselves exceedingly rare).

[Soul Surfer]

I have never seen this described explicitly in any text book but gravitons are like photons that is they are radiated when gravitating bodies interact.  Gravity waves are therefore like beams of light each wave consisting of vast numbers of individual gravitons an individual graviton can be expected to have an individual frequency determined by the interaction duration and energy and in "classical" interactions between many bodies as opposed to quantum interactions between individual particles will be radiated in a broad thermal spectrum like black body radiation.

I also expect that the energy of individual quantum gravitons to be defined by the well known Planck formula planck's constant times the frequency of the radiation  h x (greek letter nu)

Most gravitational interactions last years and months and only in extreme cases of small black holes get as short as seconds.  This means that the individual quantum energy is indescribably tiny so there are truly vast numbers of them. 

the smallest electromagnetic quanta that can be detected individually are in the infra red region and involve interaction times of picoseconds that is a million million times smaller and higher energy than the highest energy gravitons that we are likely to come across in our universe. we know of no process that can concentrate energy enough to generate atomic sized black holes that would be needed to create individual gravitons with a reasonable amount of energy for them to be detected individually.

Detecting such gravitons would require extremely sensitive probes involving the anomalous displacement of individual atoms or sub atomic particles as are being used for dark matter detection currenly with largely null results.

[distimpson]

This is another question but relates to this discussion (I think).

Can't help but wonder about gravitons. After looking at the heroic efforts of "quantum bouncer" research it raises some questions about gravitons. If with further improvements they are able to detect discrete energy levels wouldn't a transition between energy levels say something about a unit of gravitational energy? Could a transition between energy levels be used to detect or produce a graviton?

From the article link below: "Furthermore, the energy of the first excited state is 3.941x10-31 J, so the energy difference between the ground state and the first excited state is equivalent to photon with a wavelength of 1.2x10⁶ m". Couldn't a gravition of this energy be emitted/absorbed during the transition? (if all other means of energy transfer are removed-a big if but these guys are doing some amazing stuff already).

Maybe the basis of a device like the pmt only for gravitions? Or a graviton analog of the laser? What say ye Soul Surfer?

Evidence for Quantized Gravitational States of the Neutron
http://www.users.csbsju.edu/~frioux/neutron/neutron.htm

[distimpson]

Spontaneous emission of graviton by a quantum bouncer:
http://arxiv.org/pdf/quant-ph/0702256v1.pdf

Apparently I needed to do a bit more reading.