Do human sperm defy Newton’s third law? Scientists finally crack the mystery of their swim through thick fluids
Now, researchers from the University of Kyoto say that they have solved secrets: Sperm Tails, taking advantage of a phenomenon called “strange flexibility, enables Newton to act to eliminate one of the basic laws of movement.
Researchers Kenta Ishimoto, Clément Moreau and Kento Yasuda’s findings help to solve a decimal -year -old puzzle: sperm can travel quickly from thick cervical mucus or gel -like fluids that need to slow down such small swimmers to a scan.
Micro -World Physics Problem
On a human scale, swimmers push backwards to push the forces of inertia and push them forward. However, at the microscopic level, the inertia disappears and replaces its replacement with syrup dragon, physicists are called low Reynolds number flow.
Under these conditions, a simple movement of a tail does not work. Instead, objects such as sperm should never make a continuous, asymmetrical move pattern that allows the opposite movement.
Strange Flexibility: The secret weapon of the tail
Using the high -speed video of human sperm and green algae Chlamydomonas, the team matched tail movements in the “shape space ve and created an elastic matrix to calculate the internal forces. They found that the queues were strengthened by molecular engines that constantly injected energy instead of acting like passive springs.
This creates strange flexibility, a imbalance in which a bend in some of the tail sends tension along the entire structure without a reflected counter force. The result is a moving wave that moves forward without an equal push in the opposite direction.
Biology and Robotics
The study shows that as strange flexibility increases, the repulsive speed increases. This explains how human sperm beats its tails about 20 times per second, even in thick fluids.
The principle also applies to other microscopic swimmers, such as algae, and can inspire soft robots circulating in viscous environments using similar mechanics without rotating engines.
Newton rethink in active systems
The study does not overthrow Newton’s third law that manages passive systems. Instead, it indicates that force symmetry can be skipped in active systems where energy is constantly absorbed and spent.
In nature, this flexibility can help the sperm adapting the swimming mechanics in response to chemical tips or changes in viscosity when going to eggs.
