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The physics of active matter
Prof. Davide Marenduzzo
Università di Edimburgo
ABSTRACT:
Active matter is a new and growing field in physics;
it studies the behaviour of self-driven systems such as
suspensions of microbial swimmers, or self-motile cell extracts.
Unlike their more conventional passive counterparts,
such as collections of micron-size particles undergoing Brownian motion,
active matter is inherently far from thermodynamic equilibrium,
and this fact bears far-reaching consequences for the behaviour
of active matter.
We will consider here two systems in which activity leads to new physics.
First, we will see that motility leads generically to phase separation
in a concentrated suspension of swimmers; this in turn can provide
a simple framework to understand pattern formation problems in bacteria,
usually ascribed to more complicated biochemical feedback mechanisms.
Second, we will study the physics of a droplet of actomyosin,
a simple example of active material made up by mixing together
actin polymers and molecular motors.
Computer simulations show that this droplet can spontaneously break symmetry
and become self-motile, providing a possible scenario to understand
cell motility in three dimensions.
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