Hi All

An interesting preprint on the difference between our regular baryonic Universe and the possible mirror world that's implied by particle physics...

Mirror MACHOs

...which differs by being initially colder in the reheating phase resulting in higher levels of primordial helium. As a result the mirror world's stars are shorter lived by a factor of ~ 30, and are more likely to explode in supernova.

With so much helium water is likely to be a pretty scarce compound. Also carbon is likely to be more common and thus Marc Kuchner's carbon planets are probably the norm rather than the exception. Yet carbon dioxide will probably be the dominant fluid rather than hydroxides and hydrocarbons.

All in all a very interesting version of our own world since all the mirror particles are identical to our own just "different".

Adam