Theoretical & Statistical Physics

Raphael (Rafi) Blumenfeld

Theoretical physicist at Gonville & Caius College, University of Cambridge and generally a student of life.

My research grew from traditional statistical physics and branched randomly into a wide range of fields, from spin systems and various surface growth dynamics to physics of granular systems and a stab at a general theory of self-organisation.

I have been pursuing this type of problems across four decades — from my PhD in Tel Aviv though Cambridge, Princeton, Los Alamos, and back — accumulating a body of work that connects fracture mechanics, statistical physics, and the geometry of disorder.

These pages have grown uncontrollably from a modest beginning in 1993, using basic HTML, in an attempt to move from the 90s to the twenty first century.

  • Physics and geometry of particulate systems
  • Statistical mechanics of a-thermal systems
  • Self-organisation in general and of granular matter (e.g., into detailed balance)
  • Cellular, auxetic, and biologically inspired structures
  • Dynamics of curves in 3D and of excitations in spin chains
Raphael Blumenfeld

Research directions

Current focus

A theoretical formalism to model self-organisation in general

Studies of self-organising phenomena usually focus on specific systems and contexts. I have been working recently on formulating a general approach to model the characteristics of self-organised non-equilibrium steady states. The underlying idea is that self-organisation emerges when a small set of macro-states are exceptionally stable against all the noise sources and are sufficiently long-lived to be observed.

  • Self-organisation is based on a general principle
  • Detailed balance as a fingerprint o0f self-organisation in granular steady states dynamics
  • Stress and structure analysed as coupled observables
Long-running programme

Physics of granular systems: stress theory and statistical mechanics

Main activities are: formulation of a first-principles approach to stress transmission, developing a statistical mechanical formalism for the characteristics of granular systems, and predicting theoretically the random close packing fractions of planar disc systems.

  • Two-phase composite model for granular stress transmission
  • Upscaling from discrete grain contacts to continuum description
  • Marginal rigidity and the role of friction
Applied directions

From grains to cells to asteroids

The same structural-statistical ideas extend to dense flow, biological systems, porous materials, and even rubble-pile asteroids — wherever force mediation and disordered geometry matter.

  • Dense granular flow via friction-dominated "da Vinci fluid" model
  • Phase transitions in bacterial biofilms
  • Force chain dynamics in asteroid impacts

Selected publications

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