Constantino Tsallis

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Constantino Tsallis
Born	1943 Athens, Greece
Residence	Rio de Janeiro, Brazil
Citizenship	Brazilian
Nationality	Greek
Fields	Theoretical physics
Institutions	Centro Brasileiro de Pesquisas Físicas (Brazilian Physics Research Center)
Alma mater	University of Paris-Orsay
Known for	Tsallis entropy and Tsallis statistics
Notable awards	Member, Brazilian Academy of Sciences

Constantino Tsallis (1943-) is a physics researcher working in Rio de Janeiro at CBPF, Brazil. He was born in Greece, and grew up in Argentina, where he studied physics at Instituto Balseiro, in Bariloche. In 1974 he received a Doctorat d'Etat et Sciences Physiques degree from the University of Paris-Orsay. He moved to Brazil in 1975 with his family (his wife and daughter).

Tsallis is credited with introducing the notion of what is known as Tsallis entropy and Tsallis statistics in his 1988 seminal paper "Possible generalization of Boltzmann-Gibbs statistics" published in the Journal of Statistical Physics, vol. 52, p. 479-487. The generalization is considered to be one of the most viable and applicable candidates for formulating a theory of non-extensive thermodynamics. The resulting theory is not intended to replace Boltzmann-Gibbs statistics, but rather supplement it, such as in the case of anomalous systems characterised by non-ergodicity or metastable states.

One of the most impressive experimental verifications of the predictions of q-statistics concerns cold atoms in dissipative optical lattices. Eric Lutz made an analytical prediction in 2003 which was verified in 2006 by a London team.

Tsallis conjectured in 1999 (Brazilian Journal of Physics 29, 1; Figure 4):

That a longstanding quasi-stationary state (QSS) was expected in LONG-range interacting Hamiltonian systems (one of the core problems of statistical mechanics). This was quickly verified by many groups around the world.
That this QSS should be described by q-statistics instead of Boltzmann-Gibbs statistics. This was verifed in June 2007 by Pluchino, Rapisarda and Tsallis (see the last figure where instead of the celebrated Maxwellian (Gaussian) distribution of velocities (valid for SHORT-range interactions), one sees a q-Gaussian!).

These results establish that the q-entropy provides verifiable predictions from first principles as a generalization of Boltzman-Gibbs entropy for certain classes of phenomena.