Friday, January 22, 2016

Fascinating Dirac-Milne Model of Cosmology

Figs 1 and 2 from Benoit-Levy and Chardin showing
1: Age of universe as a function of temperature
2: Comprison between expansion and weak reaction rates
A news and views paper in Nature ("Exotic Atoms: Antimatter may Matter" by Thomas J Phillips) mentions the fascinating Dirac-Milne Model Universe of which I was previously unaware. There is a good description here in a paper by Beniot-Levy and Chardin.

This is very interesting because it doesn't have an inflation problem and doesn't require the hypotheising of Dark Energy. It also solves the question of why we appear to be living in a universe which is preponderantly made of matter rather than antimatter. In the Dirac-Milne model matter and antimatter repel eachother so on a large scale they will not collide except in exceptional circumstances.  This suggests that about half of the visible galaxies would be made of antimatter and that there is in fact a rough balance of matter and antimatter in the universe.

The Dirac-Milne model has flat spacetime and negatively curved spatial sections, rather than curved spacetime and flat spatial sections.  It offers a solution to a number of quite profound puzzles about comology although it introduces some of its own.

But the exciting thing is that the basic question of whether anti-hydorgen falls up or down should be resolved experimenatlly during the next 5 years. There are three competing experiments (ALPHA (from which the Nature paper came) AEGIS and GBAR). So we could be on the verge of a complete revolution in cosmology. And, pleasingly, one in which a Trinity Man (Milne) played a role. We shall see...

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