Slashdot Mirror
Physicists Propose "Perpetual Motion" Time Crystals
First time accepted submitter b30w0lf writes "It is commonly understood that crystals exist in a state of matter that is periodic in space. Meanwhile, relativistic physics tells us that we should think of time as being a physical dimension, given similar status to the other spacial dimensions. The combination of these two ideas has lead researchers at the University of Kentucky and MIT to propose special manifestations of matter which would be periodic in both space and time, dubbed 'time crystals.' Time crystals would continually transition between a set of physical states in a kind of perpetual motion. Note: the articles stress that this kind of perpetual motion in no way violates the established laws of thermodynamics. While time crystals remain theoretical, methods have been proposed for creating them. The most obvious application of time crystals is the creation of very precise clocks; however, other applications to time crystals have been proposed, ranging from quantum computing to helping us understand certain cosmological models."
If one reads the article, in the last paragraph the statement occurs: "Time crystals may sound dangerously close to a perpetual motion machine, but it is worth emphasizing one key difference: while time crystals would indeed move periodically in an eternal loop, rotation occurs in the ground state, with no work being carried out nor any usable energy being extracted from the system." They aren't proposing "mechanical perpetual motion" like we are probably all thinking at first glance. The crystal isn't doing anything abnormal. No energy is to be gained from the system, so at least mechanically, nothing is happening.
One key point that makes it not a free energy machine is that you can't actually read it or otherwise do anything useful with it (nor can it do anything) without spending extra external energy.
And in any normal situation, like sitting in a room on Earth, you might even have to spend energy keeping it undisturbed by things like thermal jostling (i.e., cooled to near absolute zero).
oh, so now dimensions with the other sign are called codimensions. Got it.
Not sure what textbook that came out of, I've never seen that convention before.
Links please!
Conversely, for those interested in the other half of the equation -- namely understanding the spatial dimension -- a new paradigm such as bivectors, trivectors, antiscalar, wedge product is necessary.
A Bigger Mathematical Picture for Computer Graphics (Eric Lengyel)
http://www.terathon.com/wscg12_lengyel.pdf
A Unified Language for Mathematics and Physics
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.134.6311&rep=rep1&type=pdf
Clifford Algebra and the Interpretation of Quantum Mechanics
http://www.montgomerycollege.edu/Departments/planet/planet/Numerical_Relativity/Geometric_Algebra/caiqm.pdf
The Unified Family of all physical quantities
http://www.naturics.eu/?page_id=1068
you blew it... Sine Field