May. 13, 2021 , 6:45 PM
Play a video of swimmer Michael Phelps in reverse, and you’ll notice right away that his stroke looks dramatically different running forward or backward in time. Such time asymmetry typifies the swimming motion of the vast majority of animals and it’s absolutely essential for bacteria and other microbes. But now, a team of physicists has developed a tiny mechanical swimmer that can inch along, even though its stroke is symmetric in time. The result opens a new conceptual lane in fluid dynamics and could aid in efforts to develop tiny swimming robots for drug delivery and other purposes.
Neutron stars may be bigger than expected, measurement of lead nucleus suggests
Apr. 27, 2021 , 11:00 AM
Say what you want about lead, it’s got a surprisingly thick skin of neutrons, that is. In fact, the layer of neutrons on the outside of a lead nucleus is twice as thick as physicists thought, according to a new study. The seemingly abstruse result could have out-of-this-world implications: Neutron stars, the ultradense spheres left behind when stars explode in supernova explosions, could be stiffer and bigger than theory generally predicts.
“It’s a fantastic experimental achievement,” says Anna Watts, an astrophysicist at the University of Amsterdam who studies neutron stars. “It’s been talked about for years and years and years, and it’s so cool to finally see it done.”
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