Mirror matter: Difference between revisions

Revision as of 15:12, 28 November 2004

Revision as of 19:17, 12 April 2005

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In [[physics]], '''mirror matter''', also called '''shadow matter''' or '''Alice matter''', is a hypothetical counterpart to regular matter suggested by T.[[Tsung D.Dao Lee]] and C.[[Chen N.Ning Yang]] [1] in [[1956]], when it was discovered that nature violates [[P-symmetry]].

Modern physics deals with three basic types of spatial [[symmetry]]: reflection, rotation and translation. The known elementary particles respect rotation and translation symmetry but do not respect mirror reflection symmetry (also called P-symmetry).

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==Observational effects of mirror matter==

If mirror matter is present in the universe with sufficient abundance then its gravitional effects can be detected. Because mirror matter is analogous to ordinary matter, it is then to be expected that a fraction of the mirror matter exists in the form of mirror galaxies, mirror stars, mirror planets etc. These objects can be detected using gravitational lensing. One would also expect that some fraction of stars have mirror objects as their companion. In such cases one should be able to detect periodic doppler[[Doppler shiftsshift]]s in the spectrum of the star [7]. There are some hints that such effects may already have been observed [9,10].

What if mirror matter does exist but has (almost) zero abundance? Like [[Magnetic_monopole|magnetic monopoles]], mirror matter could have been diluted to unobservably low densities during the [[Cosmic_inflation|inflation]] epoch. [[Sheldon_Lee_Glashow|Sheldon Glashow]] has shown that if at some high energy scale particles exist which interact strongly with both ordinary and mirror particles, [[Effective_field_theory|radiative corrections]] will lead to a mixing between photons[[photon]]s and mirror photons [11]. This mixing has the effect of giving mirror electric charges a very weak ordinary electric charge. Another effect of photon-mirror photon mixing is that it induces oscillations between positronium and mirror positronium. Positronium could then turn into mirror positronium and then decay into mirror photons. An experiment to measure this effect is currently being planned [12].

If mirror matter does exist in large abundances in the universe and if it interacts with ordinary matter via photon-mirror photon mixing, then this could be detected in dark matter direct detection experiments such as [[DAMA/NaI]] [13,14]. There would also be consequences for planetary science [15].