Herds of wildebeest, swarms of bees, and schools of fish all provide mesmerizing displays of coordinated motion. Fish, birds, and other animals numbering even in the millions can act as one not through centralized control, but through local actions and decisions, as each individual assesses the speed and orientation of its neighbors. This self-organization is … Continue reading How can a swarm swarm? — What is biophysics? #13
[Announcement: I’m giving I gave a virtual book talk Tuesday, Nov 29, 2022! Video recording link.] Many living things move. Panthers pounce, snakes slither, dolphins dive. Organs can move (such as beating hearts), and even individual cells can be motile, such as the immune cells that crawl through our tissues. How far down in scale … Continue reading Can a Molecule Walk? — What is biophysics? #12
Your genome is the totality of your genetic instructions, embodied in your DNA, of which each cell carries a copy. (Two copies, but let’s ignore that.) How big is your genome? Often, the answer is given in terms of base pairs — the rungs of the ladder of double-stranded DNA. For humans, it’s 3 billion … Continue reading How Big Is Your Genome? — What is biophysics? #10
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 … Continue reading Are molecules ever still? — What is biophysics? #7
The realization that electromagnetic waves are quantized — that light interacts in discrete packets — marked the beginning of quantum mechanics. Whether this fundamental attribute of the physical world sets the performance limits of human vision is a fascinating biophysical question. It’s so fascinating that Bill Bialek’s excellent graduate-level biophysics textbook begins with it, and … Continue reading Can you see single photons? — What is biophysics? #6
We’ve all seen ants carrying seeds, crumbs, other insects — things whose mass is a good fraction of their own. Most of us couldn’t lift things that are so heavy relative to ourselves, and so ants and many other tiny creatures have reputations for being strong. Is this justified? Answering this question brings up the … Continue reading Are Ants Really So Strong? — What is biophysics? #5
The third in a series of biophysical questions (one, two). Finding food is an essential activity for any organism. We and many other animals interpret sights, sounds, and smells to make decisions about where to go or what to do to get things to eat. But what about a bacterium, a single-celled organism just a … Continue reading Can a brainless bacterium navigate? (What is biophysics? #3)
The second in a series of biophysical questions. Proteins are molecules. As is the case for every molecule, the constituent atoms and inter-atomic bonds determine the overall shape. In general, a small or stiff molecule has a well-defined form. In contrast, long, chain-like molecules as found in plastics or the gel-formers of the last post … Continue reading What’s the shape of a protein? (What is biophysics? #2)
An introduction to the series: It’s easy to write that biophysics is the intersection of biology and physics, but this is a minimal and cryptic description. We could elaborate, and describe biophysics as the study of how living things use physical forces to shape themselves, how we can harness physical processes for technological ends, and … Continue reading How can you push DNA through Jello? (What is biophysics? #1)
The Eighteenth Elephant 