Israeli Researchers Discover Living Matter Defies Physical Laws

Scientists at Ben-Gurion University in Israel have found that moving bacteria and human cells spontaneously violate classical laws of physics. In classical physics, elongated objects moving together align like liquid crystals, creating topological defects that resemble fingerprint patterns. These defects are predicted to move symmetrically along straight lines when pairs interact. However, the Israeli researchers observed that living systems break this mirror symmetry. Experiments with fast-moving Bacillus subtilis bacteria and slower human respiratory epithelial cells showed these topological defects moving in curved, spiral paths, rotating either clockwise or counterclockwise.

To explain this phenomenon, the researchers developed a new model. It incorporates the fact that self-propelled cells use chemical fuel for directed movement. When this directed motion is superimposed on a liquid crystal structure, it creates a torque at the center of a defect, causing it to move in a spiral. The study, published in Nature Physics, suggests that the self-propulsion of individual cells fundamentally alters collective behavior at larger scales.

The authors stated, "Our results show that the ability of individual cells to self-propel fundamentally changes collective behavior at larger scales." They added that their work provides a new physical basis for describing and modeling self-organizing living communities. Understanding these movement mechanisms is crucial in biology, explaining how bacterial colonies form drug-resistant biofilms and how tissue layers guide cell movement for wound healing.