Introduction
We are a theoretical group interested
in the many body behavior of
physical and biological systems in which disorder and strong
interactions play and important role.
We use
a
combination
of analytical and computational methods. Systems of interest include
disordered solids, complex networks, population genetics and
evolution, inverse problems, reliability theory, swarms and active
matter, and various foundational questions in quantum manybody theory
and statistical mechanics.
Our
research is driven by three
fundamental
questions:
(1) Universality: To what extent do microscopic laws determine
macroscopic behavior? (2) Statistics: How should microscopic laws
should be transformed to give macroscopic ones? (3) Inversion: Can
microscopic laws be uniquely determined from macroscopic
observations?
Disintegration of Macromolecules
How and why do
complex
structures fall apart? We study the thermal stress response of large
carbon nanoballs and nanotoroids. Read more.

Disordered
Solids
Materials
such as glasses, polymers, disordered crystals, quasicrystals and
proteins lack long range order, and are thus referred as disordered
solids. The standard model describing disordered solids at low
temperatures postulate that these materials are composed of two level systems, i.e. atoms, or
groups of atoms with two available discrete configurations.
All disordered solids universally exhibit
certain properties which cannot be explained by the two level systems
model. Here
is a critique of the
said model, and here is a more general model, from which the universality
is derived.
Evolution
of Aging
Neutral
(nonselective) evolution establishes random dependencies between
cells. Over many generations every cell depends on at least one other
to survive.
During
an individual lifetime cells have a small probability
of malfunctioning. However malfunctioning cells cause further
malfunctions, eventually leading to a catastrophic
collapse.
The
accumulation of damage is statistically irreversible over a very
large parameter regime even if the cells are allowed to repair.
Therefore it is not evolutionarily economical to do much repair. Read
more.

Symbiogenesis
Start with a large number
of unrelated species, put them together
and wait for many generations. Eventually the interactions between them
evolve into a tangled web of exchanges  so much, that no species can
survive in isolation. Above are connectivity matrices and phylogenic
trees of two such communities subject to different selective pressures.
Higher pressures induce community formation. Read
more.
Model Awareness
A
model need not be a passive descriptor of its
subject. If the subject is affected by the model building process, the
model must be updated in real time. In some cases the model will drive
the subject away from its own predictions, and the two will never reach
an
equilibrium. Read
more.
