Florin Diacu

Florin Nicolae Diacu (April 24, 1959 – February 13, 2018) was a Romanian Canadian mathematician and author.

He graduated with a Diploma in Mathematics from the University of Bucharest in 1983.

Between 1983 and 1988 he worked as a math teacher in Mediaș.

In 1989 he obtained his doctoral degree at the Heidelberg University in Germany with a thesis in celestial mechanics written under the direction of Willi Jäger.

After a visiting position at the University of Dortmund, Diacu immigrated to Canada, where he became a post-doctoral fellow at Centre de Recherches Mathématiques (CRM) in Montreal.

In the early 1990s he proposed the study of Georgi Manev's gravitational law, given by a small perturbation of Newton's law of universal gravitation, in the general context of (what he called) quasihomogeneous potentials.

In several papers, written alone or in collaboration, he showed that Manev's law, which provides a classical explanation of the perihelion advance of Mercury, is a bordering case between two large classes of attraction laws.

Several experts followed this research direction, in which more than 100 papers have been published to this day.

Diacu also obtained some important results on a conjecture due to Donald G. Saari, which states that every solution of the n-body problem with constant moment of inertia is a relative equilibrium.

Diacu's later research interests regarded the n-body problem in spaces of constant curvature.

For the case n=2, this problem was independently proposed by János Bolyai and Nikolai Lobachevsky, the founders of hyperbolic geometry.

Since 1991, he was a professor at the University of Victoria in British Columbia, where he was the director of the Pacific Institute for the Mathematical Sciences (PIMS) between 1999 and 2003.

He also held short-term visiting positions at the Victoria University of Wellington, New Zealand (1993), University of Bucharest, Romania (1998), University of Pernambuco in Recife, Brazil (1999), and the Bernoulli Center at École Polytechnique Fédérale de Lausanne, Switzerland (2004).

Diacu's research was focused on qualitative aspects of the n-body problem of celestial mechanics.

But though many papers were written on this subject, the equations of motion for any number, n, of bodies were obtained only in 2008.

These equations provide a new criterion for determining the geometrical nature of the physical space.

For example, should some orbits be proved to exist only in, say, Euclidean space, but not in elliptic and hyperbolic space, and if they can be found through astronomical observations, then space must be Euclidean.

In 2015 Diacu was presented with the J. D. Crawford Prize from SIAM, awarded for outstanding research in nonlinear science, "for the novel approach to the n-body problem in curved space, blending dynamical systems, differential geometry, and geometric and celestial mechanics in a lucid, inspirational manner."

Apart from his mathematics research, Diacu was also an author of several successful books.

He wrote a monograph about celestial mechanics and a textbook of differential equations.

The students at the University of Victoria signed a petition against the textbook that Dr. Diacu had written.

The students asked the University administration to permanently withdraw the textbook from the course.

Lately he became interested in conveying complex scientific and scholarly ideas to the general public.

His most successful books in this sense are:

In 2017 he became a Professor and Head of Studies of Mathematical, Computational & Statistical Sciences at Yale-NUS College in Singapore.