Quantum Loops -- What Happened Before the Big Bang

[Elmore Furth]

Here is one of several speculations about what happend before the BIg Bang.

Physicists from the Faculty of Physics, University of Warsaw have put forward -- on the pages of Physical Review D -- a new theoretical model of quantum gravity describing the emergence of space-time from the structures of quantum theory. It is not only one of the few models describing the full general theory of relativity advanced by Einstein, but it is also completely mathematically consistent. "The solutions applied allow to trace the evolution of the Universe in a more physically acceptable manner than in the case of previous cosmological models," explains Prof. Jerzy Lnallewandowski from the Faculty of Physics, University of Warsaw (FUW).

While the general theory of relativity is applied to describe the Universe on a cosmological scale, quantum mechanics is applied to describe reality on an atomic scale. Both theories were developed in the early 20th century. Their validity has since been confirmed by highly sophisticated experiments and observations. The problem lies in the fact that the theories are mutually exclusive.

In order to gain at least some knowledge of quantum gravity, scientists construct simplified quantum models, known as quantum cosmological models, in which space-time and matter are expressed in a single value or a few values alone. For example, the model developed by Ashtekar, Bojowald, Lewandowski, Pawłowski and Singh predicts that quantum gravity prevents the increase of matter energy density from exceeding a certain critical value (of the order of the Planck density). Consequently, there must have been a contracting universe prior to the Big Bang. When matter density had reached the critical value, there followed a rapid expansion -- the Big Bang, known as the Big Bounce. However, the model is a highly simplified toy model.

The real answer to the mystery of the Big Bang lies in a unified quantum theory of matter and gravity. One attempt at developing such a theory is loop quantum gravity (LQG). The theory holds that space is weaved from one-dimensional threads. "It is just like in the case of a fabric -- although it is seemingly smooth from a distance, it becomes evident at close quarters that it consists of a network of fibres," describes Wojciech Kamiński, MSc from FUW. Such space would constitute a fine fabric -- an area of a square centimetre would consists of 1066 threads.




The Birth of Time: Quantum Loops Describe the Evolution of the Universe

[dreamnightwind]

1. 1066 should be 10 exp 66

Interesting article. I thought that a space mesh of 1066 threads per sq centimeter sounded kind of coarse. I checked the linked article, space is apparently much finer than that, with a thread density of 10 to the 66th power. Not sure how to represent the exponent in HTML. Anyway that should be fine enough res until we all have to upgrade to Space HD.

Edit for spelling

[mike_c]

2. there's a BIG difference between 1066...

...and 10⁶⁶! :rofl:

[phantom power]

3. What's 63 orders of magnitude between friends?

[sofa king]

4. Like the difference between William the Conqueror and the Borg.

Although I'm still probably off by a couple dozen orders of magnitude.