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Study Reveals Sperm's Unique Swimming Mechanics Defying Physics

10/19/2025

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Summary

Story summary

Kenta Ishimoto of Kyoto University led a study showing human sperm swim through viscous fluids, seemingly defying Newton's third law of motion.
Published in October 2023, the research finds that sperm and green algae use flexible flagella with odd elasticity.
The team introduced the term "odd elastic modulus" to describe the flagella's internal mechanics.
These findings could inform the design of small robots mimicking biological materials.

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Story summary

Kenta Ishimoto of Kyoto University led a study showing human sperm swim through viscous fluids, seemingly defying Newton's third law of motion.
Published in October 2023, the research finds that sperm and green algae use flexible flagella with odd elasticity.
The team introduced the term "odd elastic modulus" to describe the flagella's internal mechanics.
These findings could inform the design of small robots mimicking biological materials.