When tiny microbes jam up like fans exiting a baseball stadium, they can do some real damage.
University of California, Berkeley, physicists found this out the hard way when the baker's yeast cells (Saccharomyces cerevisiae) they were studying multiplied so prolifically that they burst the tiny chamber in which they were being raised.
When UC Berkeley postdoctoral fellow Morgan Delarue measured the force the growing mass of cells exerted as they pushed against one another, he calculated that it can be nearly five times higher than the pressure in a car tire -- about 150 psi, or 10 times atmospheric pressure.