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The "strange elastic modulus" allows the law of life to circumvent the laws of physics.
Human spermatozoa were found to violate Newton's third law, which states: "Action is always counteracted." It turns out that when spermatozoa move, they distort their bodies in such a way that the environment does not respond to them in accordance with this law.
In the new study, the researchers analyzed Chlamydomonas algae and data on human sperm. They identified mechanical interactions that they called the "strange elastic modulus" and that contradict Newton's third law.
Both Chlamydomonas and spermatozoa use hair extensions called flagella to move around. Flagella protrude from the cell, like a tail, and help it move, changing shape when interacting with the surrounding fluid. They do this unsymmetrically, without eliciting an equal and opposite response from the environment, thus violating Newton's law.
However, the elasticity of the flagella does not fully explain how the cell can move. This is where the "strange elastic modulus" comes into play, allowing cells to move their flagellae without significant energy losses, which would otherwise inhibit their mobility.
The higher the "strange elastic modulus" of the cell, the better the flagella can swing without much loss of energy, and the better the cell can move forward, contrary to physics.
Spermatozoa and algae are not the only owners of flagella. Many microorganisms have such outgrowths, which indicates the possible existence of other "intruders". Understanding and classifying cells or organisms that are capable of asymmetric movement can be very useful, the authors of the study believe.
The approach proposed by the scientists could help create small, elastic robots that can violate Newton's third law, said Kenta Ishimoto, one of the study's authors from Kyoto University in Japan.
The study is published in the journal PRX Life.
Human spermatozoa were found to violate Newton's third law, which states: "Action is always counteracted." It turns out that when spermatozoa move, they distort their bodies in such a way that the environment does not respond to them in accordance with this law.
In the new study, the researchers analyzed Chlamydomonas algae and data on human sperm. They identified mechanical interactions that they called the "strange elastic modulus" and that contradict Newton's third law.
Both Chlamydomonas and spermatozoa use hair extensions called flagella to move around. Flagella protrude from the cell, like a tail, and help it move, changing shape when interacting with the surrounding fluid. They do this unsymmetrically, without eliciting an equal and opposite response from the environment, thus violating Newton's law.
However, the elasticity of the flagella does not fully explain how the cell can move. This is where the "strange elastic modulus" comes into play, allowing cells to move their flagellae without significant energy losses, which would otherwise inhibit their mobility.
The higher the "strange elastic modulus" of the cell, the better the flagella can swing without much loss of energy, and the better the cell can move forward, contrary to physics.
Spermatozoa and algae are not the only owners of flagella. Many microorganisms have such outgrowths, which indicates the possible existence of other "intruders". Understanding and classifying cells or organisms that are capable of asymmetric movement can be very useful, the authors of the study believe.
The approach proposed by the scientists could help create small, elastic robots that can violate Newton's third law, said Kenta Ishimoto, one of the study's authors from Kyoto University in Japan.
The study is published in the journal PRX Life.
