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peeter
2008-Jul-11, 12:19 AM
I was listening to a batch of episodes today at work, including the neutrino episode (where it was mentioned that the mean free path of a neutrino was around 22 km of lead), and a questions show that mentioned gravitons.

Mention of graviton and neutrino in close proximity made me wonder about similarities and differences between the two.

If gravity is propagated by graviton exchange, it presumably needs to interact with matter in a more "normal than neutrino" fashion.

However, since the matter on both the side of the Earth that is towards the Sun and the side that is away from it attracts towards the sun (ie: F=GmM/r^2), is appears to me that mass does not really "cast shadows" that block gravitons. This makes me think that gravitons would have to be somewhat neutrino like, potentially passing through large amounts of mass.

If mass casted "shadows" that blocked gravitons perhaps there would be a measurable impact when the Sun/Earth/Moon lined up nicely?

Is a graviton even a well grounded physics idea or is this a theoretical idea or something popularized in Star Trek?

Presuming gravitons are not Star Trek physics, then how does a graviton interact with matter exactly? We have Schroedinger's equation for photon/electron interaction. What is the equation for graviton/mass interaction? In my undergrad Engineering courses (which included some basic physics) I don't recall ever seeing a graviton equation.

peeter
2008-Jul-11, 02:27 AM
Replying to my own post after some googling (bad form probably, ... I should have googled first). Looks like graviton is theoretical physics at the moment, and has a place in string theory (so may be Star Trek physics;)

The most promising looking answer I can spot to my question about how it may behave if it does exist is in "Feynman Lectures on Gravitation" ... but it looks like I'll have to learn General Relativity and QED first if I want to read that book.

Lightning Bug
2008-Jul-11, 06:05 AM
Give Feynman a try. See the last chapter of "Lectures on Physics volume 2" You can get the basic facts without over due concern for Relativity and QED.

peeter
2008-Jul-11, 02:44 PM
That's the curved space chapter. I'm still working on SR;)