Biological complexity: sperm defy Newton's 3rd law (Introduction)

by David Turell , Friday, October 27, 2023, 00:18 (183 days ago) @ David Turell

The action reaction law tha makes rockets fly:

https://www.newscientist.com/article/2397442-sperm-caught-breaking-newtons-third-law-of...

"To work out how the cells manage to move despite this apparent obstacle, the researchers analysed the motion of sperm and algal cells’ flagella as they swam. They found that these flagella have an unusual property, dubbed “odd” elasticity, which allows them to wave without losing much energy to the surrounding fluid.

"The researchers quantified the cells’ odd elasticity and arrived at a number called the “odd elastic modulus”. The higher this number, the more a flagellum can wave without the surrounding liquid suppressing its motion. This allows the cell to move forward non-reciprocally.

"Clément Moreau at Kyoto University, who also worked on the study, says calculating the odd elastic modulus for many different micro-swimmers could help scientists classify them and work out whether there are additional features that help them disobey Newton’s third law.

"At present, we don’t know of all the microscopic process that help tiny swimmers defy this law of motion, says Piotr Surówka at the Wrocław University of Science and Technology in Poland. He says being able to calculate the odd elastic modulus and similar numbers could help create a “dictionary” of organisms that are capable of non-reciprocal movement."

Comment: sperm have just so much energy stored. They must reach the egg quickly. The mechanics of how their flagella work, but I'll bet it mimics the bacterial method of sliding straight parts. This is a very purposeful design that cannot be developed by chance steps. Beating Newton's Third law is no mean feat.