No. Nor are atoms, viruses, or grains of sand. It is a fundamental truth that everything is in motion, shaking, twisting, and turning at random with an intensity that depends on temperature, motionless only at the unattainable limit of absolute zero. Though this is a manifestation of physics, its consequences for biology are profound and are still being elaborated.
Random motion governs and explains such phenomena as the transmission of neurotransmitters across synapses and the folding of proteins into specific shapes. Its consequences for life are still being explored and so I include “Are molecules ever still?” in my list of “What is biophysics?” questions that give a sense of the field. (Posts one and six in the series.)
Random motion gets a chapter of its own in my pop-science biophysics book, and the broader manifestations of randomness form one of the four cross-cutting biophysical themes I describe. (The usual links: My description, Publisher, Amazon.) It is hard to think of anything that is simultaneously as important to the living world and as less well known by the broader public than the role of randomness in life.
Today’s illustration: Insulin, a protein. I hoped to illustrate motion in a static painting by mimicking the Italian futurists, but I don’t think I succeeded. Rather than kaleidoscopic shards that bring to mind motion, it looks like a forest of loops and curls. I wonder, though: if we didn’t have a well-formed mental image of a horse would this painting convey to us a horse in motion?
— Raghuveer Parthasarathy; June 9, 2022
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