big_bounce said:
Hello all .
I have two questions :
1 - Before inflation elementary particles such as matter and photons could not be created and destroyed or could be created and destroyed but could not be permanent ?
I mean can we say matter existed before inflation but it was created and destroyed in frame time ?
2 - if elementary particles and matter came from energy of vacuum , can we say energy has momentum ? because matter has momentum ? ( refer to conversion of momentum )
If you want answers to your question you must specify which MODEL of the pre-inflation universe. The answers depend on which theoretical model you use, of the universe around the start of expansion. The models have not been tested enough yet for one to have gained acceptance over the others.
If you want answer according to the LQC "Big Bounce" model then it is not too hard to say something because there are some fairly clear ideas proposed about matter and geometry around start of expansion.
Here is one LQC approach that appeared recently:
http://arxiv.org/abs/1211.6269
The Matter Bounce Scenario in Loop Quantum Cosmology
Edward Wilson-Ewing
(Submitted on 27 Nov 2012)
In the matter bounce scenario, a dust-dominated contracting space-time generates scale-invariant perturbations that, assuming a nonsingular bouncing cosmology, propagate to the expanding branch and set appropriate initial conditions for the radiation-dominated era. Since this scenario depends on the presence of a bounce, it seems appropriate to consider it in the context of loop quantum cosmology where a bouncing universe naturally arises. It turns out that quantum gravity effects play an important role beyond simply providing the bounce. Indeed, quantum gravity corrections to the Mukhanov-Sasaki equations significantly modify some of the results obtained in a purely classical setting: while the predicted spectra of scalar and tensor perturbations are both almost scale-invariant with identical small red tilts in agreement with previous results, the tensor to scalar ratio is now expected to be r ≈ 10
-4, which is much smaller than the original classical prediction. Finally, for the predicted amplitude of the scalar perturbations to agree with observations, the critical density in loop quantum cosmology must be of the order 10
-9ρ
Pl .
8 pages
Here is another even more recent LQC paper on the topic you were asking about:
http://arxiv.org/abs/1302.0254
The pre-inflationary dynamics of loop quantum cosmology: Confronting quantum gravity with observations
Ivan Agullo, Abhay Ashtekar, William Nelson
(Submitted on 1 Feb 2013)
Using techniques from loop quantum gravity, the standard theory of cosmological perturbations was recently generalized to encompass the Planck era. We now apply this framework to explore pre-inflationary dynamics. The framework enables us to isolate and resolve the true trans-Planckian difficulties, with interesting lessons both for theory and observations. Specifically, for a large class of initial conditions at the bounce, we are led to a self consistent extension of the inflationary paradigm over the 11 orders of magnitude in density and curvature, from the big bounce to the onset of slow roll. In addition, for a narrow window of initial conditions, there are departures from the standard paradigm, with novel effects ---such as a modification of the consistency relation between the ratio of the tensor to scalar power spectrum and the tensor spectral index, as well as a new source for non-Gaussianities--- which could extend the reach of cosmological observations to the deep Planck regime of the early universe.
64 pages, 15 figures
========================
THIS IS IMPRACTICALLY LONG FOR OUR PURPOSES. I would suggest only sampling this excerpt on page 53:
==quote page 53==
o limit our numerical simulations to φB 2 is not physically restrictive.
To summarize, by analyzing the pre-inflationary dynamics in detail we arrived at two main conclusions. First, there do exist natural initial conditions at the bounce which lead to a completion of the standard inflationary scenario to include the quantum gravity regime. In this completed theory, one has a consistent evolution all the way from the deep Planck regime that accounts for the inhomogeneities seen in the CMB. Since the origin of the large scale structure can be traced back to these inhomogeneities, now one can systematically trace back the seeds of this structure to the quantum fluctuations of the initial state at the LQC bounce itself. Second, there is a narrow window in the φB parameter space for which the state at the onset of inflation would not be the BD vacuum. While the LQC and the standard inflation predictions are both compatible with current observations, future observations should be able to distinguish between the two. Thus, there is a potential to extend the reach of observational cosmology all the way to the Planck scale. Of course, since the window is narrow, the ‘a priori’ probability of its being realized in Nature is small. This is compensated by the fact that, if observations are compatible with φB being in this window, the initial conditions would be narrowed down tremendously, making very detailed calculations and predictions feasible.
==endquote==
BTW "BD vacuum" means "Bunch-Davies vacuum"---you could probably look that up in Wikipedia.
We have to find something that is more to the point.
Let's glance at this:
http://arxiv.org/abs/1211.1354
An Extension of the Quantum Theory of Cosmological Perturbations to the Planck Era
Ivan Agullo, Abhay Ashtekar, William Nelson
(Submitted on 6 Nov 2012 (v1), last revised 16 Jan 2013 (this version, v2))
Cosmological perturbations are generally described by quantum fields on (curved but) classical space-times. While this strategy has a large domain of validity, it can not be justified in the quantum gravity era where curvature and matter densities are of Planck scale. Using techniques from loop quantum gravity, the standard theory of cosmological perturbations is extended to overcome this limitation. The new framework sharpens conceptual issues by distinguishing between the true and apparent trans-Planckian difficulties and provides sufficient conditions under which the true difficulties can be overcome within a quantum gravity theory. In a companion paper, this framework is applied to the standard inflationary model, with interesting implications to theory as well as observations.
50 pages, published in Physical Review D.
The Planck Era is the era around the bounce, which came before inflation, so this might have some answers to your questions.
