Imagine you and your friends are trapped by a super-villain in a cage. There is a giant gear with a diameter half the length of a football field in the center. The only way to open the cage door, get out, and stop the villain’s evil plans will be to rotate this gear by one full revolution. This is a daunting task for one person — but if you have enough friends, you can grab the gear’s teeth and push it together to escape. An analogous task is faced by flocks of tiny bacteria in today’s two featured papers. In “Bacterial ratchet motors”, Di Leonardo and colleagues discuss the mechanics of bacteria pushing a single gear, and in “Swimming bacteria power microscopic gears”, Sokolov and colleagues discuss how bacteria can interact to power more than one gear.
What does a physicist study? If you ask this question to the general public, you’re likely to hear back either about the extremely small — quantum physics, particle physics — or the extremely large — general relativity or cosmology. Indeed, those are probably the most visible fields of physics, having been depicted in Hollywood movies and TV series, and being prominently featured on the cover of popular science books and magazines.
This year ESOF was in Toulouse, and I was fortunate enough to be able to attend, so I want to share a few snippets of my time there, and my main takeaways.