# Can gravity be a kinematic effect?

1. Aug 30, 2008

### tomkeus

One interesting thing in quantum mechanics is that there are correlation effects which can manifest themselves as dynamic effects, for example, as kinematics of fermions can make free electron model a good approximation for some phenomenons observed in solids, by effective cancellation of very strong Coulomb interactions.

Now, could it be possible that there is some other quantum number besides spin, which is connected with kinematics, namely mass, which creates strong correlation for large systems? I asked myself this question when I wondered why mass has dual role. It acts both as inertial parameter, both as a quantum number determining how gravitation couples to a particle. It's inertial role stems from Poincare group while dynamical role is currently based on phenomenology. On the other side, spin also gets its inertial role from Poincare group, but we have spin-statistics theorem connecting it to kinematics which is in term responsible for appearance of what are effectively dynamical effects throughout nature.

In a way, gravitation as kinematic correlation would put mass and spin, as two quantum numbers stemming from symmetry, on equal footing.

Now since I am a noob (busy one currently) I don't have enough knowledge to put some serious thought into this so I would like to here some thoughts from pros on this (and hopefully learn something), for example, are there any principles that tell us that gravity must be interaction in classic sense, ie. being transmitted by particle, corresponding to gauge potential etc.

2. Aug 30, 2008

### tomkeus

Just to add something I think I wasn't particularly clear about, and that is how this effect could possibly work. Consider following, let's say this correlation is not playing with weak, strong and EM interaction but with another, a kind of gravity which is more similar to previous three, for example, it can be grouped under same SU(n) gauge program, it's energy scale is much more similar to previous three and it's renormalizable. All the differences we observe are the result of particle kinematics conditioned by their mass.

3. Aug 30, 2008

### jal

Are you familiar with
http://arxiv.org/abs/0806.4239
On the emergence of time and gravity
Authors: Florian Girelli, Stefano Liberati, Lorenzo Sindoni
(Submitted on 26 Jun 2008)
In recent years, a new approach to these old problems has been gaining momentum and many authors have been advancing the idea that gravity could all in all be an intrinsically classic/large scale phenomenon similar to a condensed matter state made of many atoms [7]. In this sense gravity would not be a fundamental interaction but rather a large scale/numbers effect, something emergent from a quite different dynamics of some elementary quantum objects. In this sense, many examples can be brought up, starting from the causal set proposal [8], passing to group field theory [9] or the recent quantum graphity models [10] and other approaches (see e.g. [11]).
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4. Aug 30, 2008

### tomkeus

No, but it's nice to see my reasoning as not totally stupid

Anyway, thanks for the reference and I would still like to hear what people think about some sort of "mass-statistics" connection.