Bristol discovery reveals tractionless motion is possible

In an article published in Physical Review Letters, Bristol scientists have answered the fundamental question: "Is it possible to move without exerting force on the environment?", by describing the tractionless self-propulsion of active matter. Understanding how cells move autonomously is a fundamental question for both biologists and physicists. Experiments on cell motility are commonly done by looking at the motion of a cell on a glass slide under a microscope. In those conditions, cells are observed to "crawl" on the surface. Crawling is well-understood: cells attach themselves to the surface and use these anchor points to push themselves forward (like crawling on the ground). However, crawling is very inefficient in vivo, where cells move through complex 3D environments. Scientists from the School of Mathematics at Bristol have identified a different propulsion mechanism particularly suited for cell motion in tissues - one that doesn't rely on force transmission through anchor points.