Question regarding quantum gravity.

[Sigurdsson]

I was recently reading a small news article named Experiments Show Gravity Is Not an Emergent Phenomenon.
http://www.technologyreview.com/blog/arxiv/27102/?ref=rss.

It goes on about gravity not being a traditional force but a emergent phenomenon. But the interseting thing is

Kobakhidze argues that since each quantum particle must be described by a large number of other particles

I've gone through undergraduate courses in QM but have never heard of this. We can construct a wave function describing a quantum particle but how is this coherent with the statement above?

 

[cgk]

I've gone through undergraduate courses in QM but have never heard of this. We can construct a wave function describing a quantum particle but how is this coherent with the statement above?

The journalists only know what he said originally, but in this form this statement is clearly false. And N-particle quantum system has exactly N particles, and can be described as such. E.g., when simulating a molecule (a very quantum-y system!), the number of electrons is generally fixed and no other particles than the input electrons occur.

In field theories there are also ways of describing a few real particules using additional virtual particles. But: (i) doing that is not necessary (they result from a particular form of a perturbation expansion of interactions), and (ii) the virtual particles are not real (they just represent terms the the mentioned perturbation expansion, not actual particles in any sense).

 

[fzero]

If you read the paper that is linked in the story, http://arxiv.org/abs/1108.4161, you'll find that Kobakhidze actually writes (emphasis mine):

"An inevitable consequence of Verlinde’s approach is that a test particle m is described by a statistically large number n(r) of microstates which depends on the position of the particle with respect to another particle M"

The microstates in question are the ones on the holographic screen surrounding the particle of mass M. A certain mixed state, not explicitly described, of these holographic microstates corresponds to the test particle. This representation is crucial to Verlinde's model.

 

[Sigurdsson]

Oh, my bad. I thought he was generally stating that quantum particle must be described by a large number of other particles. But this is only his criticism to Verlinde's theory. Thanks guys. :)