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 Breaking Temporal Symmetry
A normal crystal is said to break spatial symmetry because its particles line up in specific directions, rather than being regularly spaced (as they are at higher temperatures). A new concept, called a space-time crystal takes that one step further by breaking temporal symmetry. Breaking temporal symmetry simply means that an object or a collection of particles experiences some kind of systematic, repeating change over time. Of course, that could simply be a planet orbiting the sun. What makes a space-time crystal special is that it breaks temporal symmetry from it's ground state. In other words, it would take energy to stop the broken temporal symmetry. Usually the opposite is true.
It sounds bizarre, but the concept was presented by Frank Wilczek in 2012 and is being pursued by several experimental groups. Frank Wilczek won the Nobel Prize in Physics in 2004 along with David Gross and David Politzer for their discovery of asymptotic fredom in the theory of the strong interaction and is currently the Herman Feshbach Professor of Physics at MIT, so the theory has some weight behind it.
Here is a recent article on the subject:
"Time Crystals" Could Upend Physicists' Theory of Time
IN FEBRUARY 2012, the Nobel Prize-winning physicist Frank Wilczek decided to go public with a strange and, he worried, somewhat embarrassing idea. Impossible as it seemed, Wilczek had developed an apparent proof of "time crystals" - physical structures that move in a repeating pattern, like minute hands rounding clocks, without expending energy or ever winding down. Unlike clocks or any other known objects, time crystals derive their movement not from stored energy but from a break in the symmetry of time, enabling a special form of perpetual motion.
"Most research in physics is continuations of things that have gone before," said Wilczek, a professor at the Massachusetts Institute of Technology. This, he said, was "kind of outside the box." Wilczek's idea met with a muted response from physicists. Here was a brilliant professor known for developing exotic theories that later entered the mainstream, including the existence of particles called axions and anyons, and discovering a property of nuclear forces known as asymptotic freedom (for which he shared the Nobel Prize in physics in 2004). But perpetual motion, deemed impossible by the fundamental laws of physics, was hard to swallow. Did the work constitute a major breakthrough or faulty logic? Jakub Zakrzewski, a professor of physics and head of atomic optics at Jagiellonian University in Poland who wrote a perspective on the research that accompanied Wilczek's publication, says: "I simply don't know."
Now, a technological advance has made it possible for physicists to test the idea. They plan to build a time crystal, not in the hope that this perpetuum mobilewill generate an endless supply of energy (as inventors have striven in vain to do for more than a thousand years) but that it will yield a better theory of time itself.
Article Continues Here
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Re: Space-Time Crystals
