Les physiciens des particules peuvent rêver à autre chose que SUSY (un 1er avril;-)
Recent astrophysical data indicates that dark matter shows a controversial behaviour in galaxy cluster collisions. In case of the notorious Bullet cluster, dark matter component of the cluster behaves like a collisionless system. However, its behaviour in the Abell 520 cluster indicates a significant self-interaction cross-section. It is hard for the WIMP based dark matter models to reconcile such a diverse behaviour. Mirror dark matter models, on the contrary, are more flexible and for them diverse behaviour of the dark matter is a natural expectation...
If the mirror dark matter were as popular as the SUSY dark matter, we would say that it is already discovered. However, it would be more fair to conclude that we need more observational evidence to ﬁrmly prove this fascinating conjecture.
Z.K. Silagadze, Mirror dark matter discovered?, 19/08/2008
La physique de l'autre côté du miroir
It is still widely known that in their famous article  Lee and Yang revealed “The fact that parity conservation in the weak interactions was believed for so long without experimental support”  and hypothesized the possibility of parity non-conservation in the weak interactions. The hypothesis turned out to be true, as the subsequent experiments had shown, and nowadays it is a ﬁrmly established fact that our universe is left-handed as far as the weak interactions are concerned. What is not so widely known is the fact that at the end of the very same paper Lee and Yang indicated how left-right symmetry of the world could be rescued by duplicating the non-symmetric part of our left-handed universe in the mirror...After a decade, Kobzarev, Okun and Pomeranchuk, inﬂuenced by the Landau’s idea of combined parity and subsequent experimental discovery of CP-violation, digged out the mirror matter concept from the literature horizon and gave it the ﬁrst serious phenomenological consideration . This paper marked the real beginning of the mirror matter story. It was argued that almost all elementary particles should be duplicated (with possible exclusion of some neutral particles) and that the mirror particles can not have common strong and electromagnetic interactions with ordinary particles. The concepts of “Mirror Matter” and corresponding invisible “Mirror World”(after Lewis Carroll’s Alice Through the Looking Glass), as complex as our own world, were introduced in this work for the first time and observational effects of the mirror matter were investigated. Some further investigations of possible astrophysical effects of the hidden sector particles followed [14, 15, 16], but the idea was still not far from the literature horizon until it was rediscovered in the modern context of renormalizable gauge theories by Foot, Lew and Volkas  and used in the context of neutrino oscillations [18, 19]. Okun’s recent review  cites more than 250 references related to the mirror matter idea and we hope that it remains outside the literature horizon. However the idea is still little known to the majority of physicists, oriented at the mainstream.
La physique de l'autre côté du mur
“In the Soviet scientific society the scientists had one freedom that scientists in the West lacked and still lack (perhaps the only real freedom that Eastern scientists had), and that was to spend time also on esoteric questions. They did not have to be scrutinized by funding agencies every now and then” . The Soviet Union disappeared and so did this freedom. You can consider this paper, if you like, as a nostalgia for this kind of freedom, enabling to escape bonds of the stiff pragmatic logic.
Z. K. Silagadze, TeV scale gravity, mirror universe, and . . . dinosaurs, 2000