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posted by janrinok on Tuesday September 13 2016, @08:22PM   Printer-friendly
from the head-explodes dept.

Are time crystals just a mathematical curiosity, or could they actually physically exist? Physicists have been debating this question since 2012, when Nobel laureate Frank Wilczek first proposed the idea of time crystals. He argued that these hypothetical objects can exhibit periodic motion, such as moving in a circular orbit, in their state of lowest energy, or their "ground state." Theoretically, objects in their ground states don't have enough energy to move at all.

In the years since, other physicists have proposed various arguments for why the physical existence of time crystals is impossible—and most physicists do seem to think that time crystals are physically impossible because of their odd properties. Even though time crystals couldn't be used to generate useful energy (since disturbing them makes them stop moving), and don't violate the second law of thermodynamics, they do violate a fundamental symmetry of the laws of physics.

However, now in a new paper published in Physical Review Letters, physicists from the University of California, Santa Barbara (UCSB) and Microsoft Station Q (a Microsoft research lab located on the UCSB campus) have demonstrated that it may be possible for time crystals to physically exist.
...
According to the physicists, it should be possible to perform an experiment to observe time-translation symmetry breaking by using a large system of trapped atoms, trapped ions, or superconducting qubits to fabricate a time crystal, and then measure how these systems evolve over time. The scientists predict that the systems will exhibit the periodic, oscillating motion that is characteristic of time crystals and indicative of spontaneously broken time-translation symmetry.


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  • (Score: 0) by Anonymous Coward on Wednesday September 14 2016, @01:23PM

    by Anonymous Coward on Wednesday September 14 2016, @01:23PM (#401767)

    I'm prepared to believe that such objects in perpetual motion exist. However, assuming they do and their lowest energy state is one of motion, how would a person be able to observe it?

    By observing an observable that changes during that motion.

    For this object to be observed, it would need to interact with the general universe in some way (emitting photons, gravity waves, transferring momentum, etc)... and that would expend energy.

    The interaction energy can be provided by the measurement device. Obviously the ground state won't emit energy on its own, otherwise it wouldn't be the ground state.

    And yes, the measurement would take it out of the ground state. Without having read the article, I'd expect them to prepare those states many times, and then measure after a different duration for different equally-prepared systems. If they see a periodicity in their measurement data, they know they have a periodic moving state.