Draft:Tommaso Ruggeri

Tommaso Ruggeri
Born	Italy
Nationality	Italian
Known for	Rational Extended Thermodynamics, Nonlinear Wave, Hyperbolic system
Scientific career
Fields	Rational thermodynamics, Nonequilibrium thermodynamics
Institutions	University of Bologna

Tommaso Ruggeri is an Italian mathematician and physicist, currently an Emeritus Professor of Mathematical Physics at the University of Bologna. He is widely recognized for his contributions to mathematical physics, specifically in the fields of nonlinear wave propagation and nonequilibrium thermodynamics. Ruggeri is one of the key figures in the development of modern Rational Extended Thermodynamics.

Early Career and Education

Ruggeri earned his master's degree in Theoretical Physics from the University of Messina, where he soon became an Assistant in Rational Mechanics. He later moved to the University of Bologna, becoming a full professor of Mathematical Physics in 1980. Throughout his career at Bologna, he held various academic and administrative roles. Ruggeri established himself as a leader in mathematical physics through his pioneering work on the propagation of nonlinear waves and the symmetrization of hyperbolic systems of balance laws, and he supervised numerous students.

Research Contributions

Nonlinear Wave Propagation

In his research on nonlinear wave propagation, Ruggeri made original contributions concerning the acceleration and shock waves in classical and relativistic continuous media. He is particularly noted for his work on the symmetrization of hyperbolic systems of balance laws, when these systems are compatible with a convex entropy density.

Einstein equation and Relativistic fluids

Together with Yvonne Choquet-Bruhat, Ruggeri wrote a highly significant paper in 1983 on the Einstein equations in the 3+1 form, proving that there is an optimal choice of the "lapse" that yields a hyperbolic system, leading to the proof of an existence theorem. Additionally, for the relativistic Euler fluid, together with Alberto Strumia, he proved the existence of a privileged field, the "main field," for which the system assumes a symmetric hyperbolic form.

Rational Extended Thermodynamics

Ruggeri is perhaps best known for his groundbreaking work in nonequilibrium thermodynamics, where he co-founded the theory of Rational Extended Thermodynamics (RET). This theory provides a bridge between macroscopic (continuum) and mesoscopic (kinetic theory) scales, offering a comprehensive framework for studying thermodynamic processes in gases and fluids.

Alongside Ingo Müller, Ruggeri co-authored the seminal book Rational Extended Thermodynamics (Springer-Verlag, 1993, 1998), which laid the foundation for further advancements in nonequilibrium thermodynamics. The theory proposed in this book has had a profound impact on the field, particularly in the study of extended thermodynamic systems that go beyond the traditional limits of classical thermodynamics.

In more recent years, Ruggeri collaborated with Masaru Sugiyama to further develop the RET framework, resulting in two significant works: *Rational Extended Thermodynamics beyond Monatomic Gas* (Springer, 2015) and *Classical and Relativistic Rational Extended Thermodynamics of Gases* (Springer, 2021). These books explore the theory in greater depth, extending its application to polyatomic gases in both classical and relativistic contexts.

Academic Recognition and Awards

Ruggeri is a member of several prestigious scientific academies, including:

• Accademia Nazionale dei Lincei – the oldest science academy in the Western world.
• Academia Europaea.
• European Academy of Sciences and Arts.
• European Academy of Sciences (EurASc).
• Academy of Sciences of Bologna, Naples, and Messina.

He has received several awards including in 2018 the International Prize Angiola Gili and Cataldo Agostinelli of the Accademia di Torino for Pure Mechanics or Classical Mathematical Physics.

Professional Roles and Visiting Professorships

Ruggeri has been invited as a plenary speaker at numerous international conferences and has served as a visiting professor at a wide range of prestigious institutions, including Stanford University, Brown University, Sorbonne University (Paris), and universities in Berlin, Seoul, Taipei, Mumbai, Hong Kong, Sydney, Kyoto, and Beijing.

In addition to his research and teaching roles, Ruggeri has held several leadership positions in scientific organizations. He served as the Director of the National Group of Mathematical Physics (GNFM) in Italy and was the President of the Scientific Committee of the Istituto Nazionale di Alta Matematica (INdAM).

Selected Works

• Rational Extended Thermodynamics (with Ingo Müller), Springer-Verlag, 1993 and 1998.
• Rational Extended Thermodynamics beyond Monatomic Gas (with Masaru Sugiyama), Springer, 2015.
• Classical and Relativistic Rational Extended Thermodynamics of Gases (with Masaru Sugiyama), Springer, 2021.
• Introduction to the Thermomechanics of Continua and Hyperbolic Systems, Springer, 2024

See also

• Hyperbolic system of Balance Laws

References

• http://www.dm.unibo.it/~ruggeri/