It is widely accepted that microorganisms are social beings. Whereas communication via chemical
signals (e.g. quorum sensing) has been the focus of most investigations, the use of physical signals
for microbial cell-cell communication has received only limited attention. Here, I argue that
physical modes of microbial communication could be widespread in nature. This is based on
experimental evidence on the microbial emission and response to three physical signals: sound
waves, electromagnetic radiation, and electric currents. These signals propagate rapidly and, even
at very low intensities, they provide useful mechanisms when a rapid response is required. I also
make some suggestions for promising future research avenues that could bring novel and
unsuspected insights into the physical nature of microbial signaling networks.
