Chaos and Nonlinearity in Dynamical Astronomy
IFPU
23 – 27 February 2026
The dynamical evolution of gravitationally interacting bodies, from the planetary systems to
cosmological scales, is largely governed by nonlinear phenomena resulting from the
inherently chaotic nature of the gravitational N-body problem for N>2. Historically, studies of
the few-body problem (typically N~10), fundamental in celestial mechanics, have relied
predominantly on perturbative methods. Conversely, for larger N typical of galactic
dynamics, the theoretical frameworks of kinetic theory and statistical physics, approaches
also prevalent in plasma physics, have been the primary tools.
Despite extensive efforts within these two most often separate communities, numerous
fundamental questions remain unresolved. Key open questions include: how does the
intrinsic chaos of the gravitational N-body problem affect the long-term stability of
astrophysical equilibrium configurations? Are chaotic phenomena in galaxy evolution driven
primarily by discrete particle interactions and close encounters, or are perturbations in the
collective gravitational potential more influential? Furthermore, do relativistic effects in
multiple systems of compact objects act as stabilizing factors, or do they amplify their chaotic
behavior? This Focus Week aims at addressing these questions through a multi-disciplinary
approach, bridging gaps between celestial mechanics, galactic dynamics, and statistical
physics.
Meeting program:
Organisers:
- A. Trani (Niels Bohr Institute, Copenhagen)
- Pierfrancesco Di Cintio (CNR-ISC, Firenze)
- Mario Spera (SISSA, Trieste)