http://esciencecommons.blogspot.com.au/2017/11/physicists-show-how-lifeless-particles.html
Emory graduate student Guga Gogia slowly “salted” micron-sized particles into a vacuum chamber filled with plasma, creating a single layer of particles levitating above a charged electrode. He kept a low gas pressure, so the particles could move freely. “After a few minutes I could see with my naked eye that they were acting strangely," Gogia says.
By Carol Clark
Physicists at Emory University have shown how a system of lifeless particles can become “life-like” by collectively switching back and forth between crystalline and fluid states — even when the environment remains stable.
Physical Review Letters recently published the findings, the first experimental realization of such dynamics.
“We’ve discovered perhaps the simplest physical system that can consistently keep changing behavior over time in a fixed environment,” says Justin Burton, Emory assistant professor of physics. “In fact, the system is so simple we never expected to see such a complex property emerge from it.”
Many living systems — from fireflies to neurons — switch behaviors collectively, firing on and then shutting off. The current paper, however, involved a non-living system: Plastic particles, tiny as dust specks, that have no “on” or “off” switches.
“The individual particles cannot change between crystalline and fluid states,” Burton says. “The switching emerges when there are collections of these particles — in fact, as few as 40. Our findings suggest that the ability for a system to switch behaviors over any time scale is more universal than previously thought.”
much more at
http://esciencecommons.blogspot.com.au/2017/11/physicists-show-how-lifeless-particles.html
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the paper:
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.119.178004
Emergent Bistability and Switching in a Nonequilibrium Crystal:
ABSTRACT:
Multistability is an inseparable feature of many physical, chemical, and biological systems which are driven far from equilibrium. In these nonequilibrium systems, stochastic dynamics often induces switching between distinct states on emergent time scales; for example, bistable switching is a natural feature of noisy, spatially extended systems that consist of bistable elements. Nevertheless, here we present experimental evidence that bistable elements are not required for the global bistability of a system. We observe temporal switching between a crystalline, condensed state and a gaslike, excited state in a spatially extended, quasi-two-dimensional system of charged microparticles. Accompanying numerical simulations show that conservative forces, damping, and stochastic noise are sufficient to prevent steady-state equilibrium, leading to switching between the two states over a range of time scales, from seconds to hours.
Emory graduate student Guga Gogia slowly “salted” micron-sized particles into a vacuum chamber filled with plasma, creating a single layer of particles levitating above a charged electrode. He kept a low gas pressure, so the particles could move freely. “After a few minutes I could see with my naked eye that they were acting strangely," Gogia says.
By Carol Clark
Physicists at Emory University have shown how a system of lifeless particles can become “life-like” by collectively switching back and forth between crystalline and fluid states — even when the environment remains stable.
Physical Review Letters recently published the findings, the first experimental realization of such dynamics.
“We’ve discovered perhaps the simplest physical system that can consistently keep changing behavior over time in a fixed environment,” says Justin Burton, Emory assistant professor of physics. “In fact, the system is so simple we never expected to see such a complex property emerge from it.”
Many living systems — from fireflies to neurons — switch behaviors collectively, firing on and then shutting off. The current paper, however, involved a non-living system: Plastic particles, tiny as dust specks, that have no “on” or “off” switches.
“The individual particles cannot change between crystalline and fluid states,” Burton says. “The switching emerges when there are collections of these particles — in fact, as few as 40. Our findings suggest that the ability for a system to switch behaviors over any time scale is more universal than previously thought.”
much more at
http://esciencecommons.blogspot.com.au/2017/11/physicists-show-how-lifeless-particles.html
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
the paper:
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.119.178004
Emergent Bistability and Switching in a Nonequilibrium Crystal:
ABSTRACT:
Multistability is an inseparable feature of many physical, chemical, and biological systems which are driven far from equilibrium. In these nonequilibrium systems, stochastic dynamics often induces switching between distinct states on emergent time scales; for example, bistable switching is a natural feature of noisy, spatially extended systems that consist of bistable elements. Nevertheless, here we present experimental evidence that bistable elements are not required for the global bistability of a system. We observe temporal switching between a crystalline, condensed state and a gaslike, excited state in a spatially extended, quasi-two-dimensional system of charged microparticles. Accompanying numerical simulations show that conservative forces, damping, and stochastic noise are sufficient to prevent steady-state equilibrium, leading to switching between the two states over a range of time scales, from seconds to hours.
