# The beginning of universe

1. Mar 31, 2006

i would like to know how to explain the beginning of universe and during high collision of high energy particles by the conservation of energy?

2. Mar 31, 2006

### AlphaNumeric

Noone yet has an explaination for the beginning of the universe, in either what created it or what happened in the first $$10^{-15}$$ seconds or so.

I'm not quite sure what you're asking about high energy particle collisions. Do you want to know how the conservation of energy plays a part in them or something else?

3. Apr 2, 2006

### Chronos

We live in interesting times . . . which basically includes everything that has happened since the first planck tick of time. What lays behind the planck wall [~10^-43 seconds] is pure speculation.

Last edited: Apr 2, 2006
4. Apr 5, 2006

### marcus

fair question. what you are asking about is the BEGINNING OF EXPANSION
that can be studied using testable quantum physics models of the early geometry of the universe. expansion is a geometric event, so to study it quantum mechanically you have to use quantum geometry----this will involve predictions and observational tests like anything else.

so? there aren't certain answers but you can sample what some people are thinking and working on. check this out

http://arxiv.org/abs/gr-qc/0602086
Quantum Nature of the Big Bang

Abhay Ashtekar, Tomasz Pawlowski, Parampreet Singh
4 Pages, 2 Figures
"Some long standing issues concerning the quantum nature of the big bang are resolved in the context of homogeneous isotropic models with a scalar field. Specifically, the known results on the resolution of the big bang singularity in loop quantum gravity are significantly extended as follows: i) the scalar field is shown to serve as an internal clock, thereby providing a detailed realization of the emergent time' idea; ii) the physical Hilbert space, Dirac observables and semi-classical states are constructed rigorously; iii) the Hamiltonian constraint is solved numerically to show that the big bang is replaced by a big bounce. Thanks to the non-perturbative, background independent methods, unlike in other approaches the quantum evolution is deterministic across the deep Planck regime."

http://arxiv.org/abs/gr-qc/0604013
Quantum Nature of the Big Bang: An Analytical and Numerical Investigation I
Abhay Ashtekar, Tomasz Pawlowski, Parampreet Singh
59 pages, 19 figures

"Analytical and numerical methods are developed to analyze the quantum nature of the big bang in the setting of loop quantum cosmology. They enable one to explore the effects of quantum geometry both on the gravitational and matter sectors and significantly extend the known results on the resolution of the big bang singularity. Specifically, the following results are established for the homogeneous isotropic model with a massless scalar field: i) the scalar field is shown to serve as an internal clock, thereby providing a detailed realization of the emergent time' idea; ii) the physical Hilbert space, Dirac observables and semi-classical states are constructed rigorously; iii) the Hamiltonian constraint is solved numerically to show that the big bang is replaced by a big bounce. Thanks to the non-perturbative, background independent methods, unlike in other approaches the quantum evolution is deterministic across the deep Planck regime. Our constructions also provide a conceptual framework and technical tools which can be used in more general models. In this sense, they provide foundations for analyzing physical issues associated with the Planck regime of loop quantum cosmology as a whole."

In contemporary (post 2001) quantum cosmology what used to be called the Big Bang-----the start of expansion----is not a "singularity" but rather a transition between a contracting phase and an expanding phase.

Parampreet Singh, one of Ashtekar's co-authors, is a specialist in the testing aspect, what to look for to prove or disprove the model.

Models like this are not intended to be immedieately BELIEVED----the idea is to study and test them. This particular quantum cosmology model that Ashtekar is talking about is being taken increasingly seriously by other cosmologists.

Anyway, excellent question----would lead you to some very recent research by first-rate people.