NONEXTENSIVE THERMOSTATISTICS CAN YIELD APPARENT MAGNETISM

Bacry [Phys. Lett. B 317, 523 (1993)] showed that, on the basis of a d eformed Poincare group, special relativity yields a nonadditive energy for large systems, i.e., a total energy (of the Universe) which would not be proportional to the number of particles. He consistently argue d that this effect could explain (part of) the so-called dark matter. By considering noninteracting spins at thermal equilibrium in the pres ence of an external magnetic field, we show here that the recently int roduced nonextensive (nonadditive) thermostatistics could account for a theoretically possible ''dark magnetism'' (the apparent number of sp ins being smaller or larger than the actual one).