"Nature plays the tricks that it knows how to play over and over again," said Nagel, the Stein Freiler Distinguished Service Professor in Physics at Chicago. Nagel and Jaeger co-authored the paper, along with Xiang Cheng, a graduate student in physics at Chicago; German Varas, a graduate student in physics at the University of Chile; and Daniel Citron, a Chicago undergraduate in physics.
Scientists have attained a good understanding of equilibrium phenomena, which are governed primarily by temperature or pressure. But what about phenomena that have been pushed far beyond their equilibrium states, like a jet of sand" What about quark-gluon plasma, the mixture of subatomic particles that existed for perhaps a few millionths of a second after the big bang"
"We really don't know what the right concepts are to describe this," Nagel said. "We love the physics of granular material because it allows us entrée into this question in relatively simple experiments."
In designing their tabletop experiment, the Chicago team addressed a fundamental question about equilibrium: Under what conditions does a collection of molecules, sand grains or other particles behave like a liquid" Macroscopic and subatomic particles sometimes behave in similar ways. The particles in the Chicago experiment are large enough to allow scientists to track under precisely controlled conditions, an option not available on the subatomic scale.
A paper published in 1883 that described the water-bell phenomenon inspired the granular-stream experiment. The paper reports how a stream of water hitting a narrow, flat, circular target becomes transformed into the thin, hollow shape of a bell. Would a stream of granular materials do likewise"
Cheng, the Chicago graduate student, performed an experiment to find out. He blasted globs of glass and copper beads through a tube into a flat target. "The answer is you can in fact see those bells," said Jaeger, a Professor in Physics. "Specifically, we find that the rapid collisions of densely packed particles produce the liquid state that we can then observe afterward, when everything flies apart and produces these beautiful envelope structures."
Scientists have seen similar structures in the quark-gluon plasma experiments conducted at Brookhaven National Laboratory with the Relativistic Heavy Ion Collider. The $500 million RHIC smashes gold atoms into each other at nearly the speed of light. The tabletop Chicago experiment launches jets of granular materials into a flat target at no more than 12 miles an hour.
"There couldn't be anything farther apart than our experiments and those at RHIC," Nagel said. For that very reason, the Chicago team conducted their test under a variety of conditions to ensure that interactions between the granular particles and the air did not affect the experimental result. "The key ingredient is the high density of rapid collisions," Jaeger said.
The similarity between the granular-jet and RHIC experiments are surprising because scientists would expect quantum physics to dominate the results of the latter. Quantum physics typically rules the atomic and subatomic world. Classical physics, meanwhile, applies to the much larger objects of everyday life.
Nevertheless, the RHIC scientists have interpreted their results in a classical way. "They say it's like a liquid. That's a classical concept. Then they ascribe to this liquid such things as viscosity. Well, that's a classical concept," Nagel said. "Some of these phenomena that appear at this very microscopic, quantum scale echo phenomena that occur on the classical scale.
"That's the amazing thing about physics. The laws you have at one level really are the same as at other levels, or at least influence what happens at other levels. Certain principles are just invariant. Conservation of energy and momentum-you can't get away from these things on any scale."
Steve Koppes | EurekAlert!
One-way roads for spin currents
23.05.2018 | Singapore University of Technology and Design
Tunable diamond string may hold key to quantum memory
23.05.2018 | Harvard John A. Paulson School of Engineering and Applied Sciences
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
23.05.2018 | Life Sciences
23.05.2018 | Life Sciences
23.05.2018 | Physics and Astronomy