From Sam Edge, Ringwood, Hampshire, UK
I was interested to read about some potential consequences should dark matter consist of “mirror matter”. However, if this exists as a mirror duplicate of all particles and the electromagnetic, weak and strong forces, I question why gravity would be the same for mirror matter as for conventional matter, which it would have to be if mirror matter is dark matter (6 January, p 18).
Dark matter is usually postulated as material that interacts normally in terms of mass and gravity, but very weakly in terms of the other forces. A simpler answer would be that it is conventional matter of a form not covered by the standard model of particle physics, rather than a whole mirror copy of everything we already have except gravity.
