Perpetual Motion Test Could Amend Theory of Time

Physicists plan to create a “time crystal” — a theoretical object that moves in a repeating pattern without using energy — inside a device called an ion trap. (Photo: Courtesy of Hartmut Häffner)

Courtesy of Hartmut Häffner






A Crazy Concept



Courtesy of Frank Wilczek

The Nobel Prize-winning physicist Frank Wilczek often develops outlandish theories that eventually enter the mainstream. “Of course not everything I do works,” he says.





The Big Test








To Build an Ion Ring

In Albert Einstein’s theory of general relativity (the body of laws governing gravity and the large-scale structure of the universe), the dimensions of time and space are woven together into the same fabric, known as space-time. But in quantum mechanics (the laws governing interactions on the subatomic scale), the time dimension is represented in a different way than the three dimensions of space — “a disturbing, aesthetically unpleasant asymmetry,” Zakrzewski said.

The different treatments of time may be one source of incompatibility between general relativity and quantum mechanics, at least one of which must be altered for there to be an all-encompassing theory of quantum gravity (widely viewed as a major goal of theoretical physics). Which concept of time is right?

If time crystals are able to break time symmetry in the same way that conventional crystals break space symmetry, “it tells you that in nature those two quantities seem to have similar properties, and that ultimately should reflect itself in a theory,” Häffner said. This would suggest that quantum mechanics is inadequate, and that a better quantum theory might treat time and space as two threads of the same fabric.

Illustration by Courtesy of Hartmut Häffner

An illustration of the time crystal experiment planned at UC-Berkeley. Electric fields will be used to corral calcium ions into a 100-micron-wide “trap,” where they will form a crystalline ring. The scientists believe a static magnetic field will cause the ring to rotate.

The Berkeley-led team will attempt to build a time crystal by injecting 100 calcium ions into a small chamber surrounded by electrodes. The electric field generated by the electrodes will corral the ions in a “trap” 100 microns wide, or roughly the width of a human hair. The scientists must precisely calibrate the electrodes to smooth out the field. Because like charges repel, the ions will space themselves evenly around the outer edge of the trap, forming a crystalline ring.

At first, the ions will vibrate in an excited state, but diode lasers like those found in DVD players will be used to gradually scatter away their extra kinetic energy. According to the group’s calculations, the ion ring should settle into its ground state when the ions are laser-cooled to around one-billionth of a degree above absolute zero. Access to this temperature regime had long been obstructed by background heat emanating from trap electrodes, but in September, a breakthrough technique for cleaning surface contaminants off electrodes enabled a 100-fold reduction in ion trap background heat. “That’s exactly the factor we need to bring this experiment into reach,” Häffner said.

Next, the researchers will switch on a static magnetic field in the trap, which their theory says should induce the ions to start rotating (and continue doing so indefinitely). If all goes as planned, the ions will cycle around to their starting point at fixed intervals, forming a regularly repeating lattice in time that breaks temporal symmetry.

To see the ring’s rotation, the scientists will zap one of the ions with a laser, effectively tagging it by putting it into a different electronic state than the other 99 ions. It will stay bright  (and reveal its new location) when the others are darkened by a second laser.

If the bright ion is circling the ring at a steady rate, then the scientists will have demonstrated, for the first time, that the translational symmetry of time can be broken. “It will really challenge our understanding,” Li said. “But first we need to prove that it does indeed exist.”

Until that happens, some physicists will remain deeply skeptical. “I personally think it’s not possible to detect motion in the ground state,” Bruno said. “They may be able to make a ring of ions in a toroidal trap and do some interesting physics with that, but they will not see their ever-ticking clock as they claim.”

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  • Exciting news, and a lovely theory. If there is only one voice of opposition, I would think the likelyhood for at least some very interesting advances in science are good. Either way I cant wait to see the results

  • Besides perpetual motion are there other far reaching implication if there experiment works?
    I’d like to learn about what else could be done.

  • I’m missing what is really new here – continuous periodic motion is implied by basic quantum mechanics. The simplest interpretation of the quantum numbers of an electron in a hydrogen atom is that the electron really does orbit the proton. De Broglie’s matter waves were conceived as circular motions of a point particle, with the frequency found by noticing that energy is equivalent to both mass and frequency, the former scaled by c-squared and the latter by Planck’s constant. Schrodinger worked out the implications for the Dirac (electron) equation, calling the phenomenon “zitterbewegung”, meaning “trembling motion”. It is of very high frequency – 1.6E21 Hz = 1.6 zettaherz, or billion trillion cycles per second, double that of the De Broglie wave of an electron.

    As Oersted Medal winner David Hestenes worked out (using his marvelously clear applied, real-valued Clifford algebras, or “Geometric Algebra”, a lingua franca for mathematical physics) zitterbewegung at its simplest is a helical, light-speed motion of a point charge around its average path.* Further he found that the orientation of the helix is the electron spin, the curvature of the helix is the electron mass, the angle of the particle around the helix is the electron phase, and the helical motion creates a static magnetic dipole and a rotating electric dipole. This is far more comprehensible than the usual explanations (insofar as there are any usual explanations!). His interpretation was borne out by the discovery an absorption of 81.1MeV electrons in silicon crystals, due to the spatial zitter frequency and its electric dipole lining up at that speed with the spatial period of the crystal lattice. Before Hestenes’ explanation, the experimental results were so unexpected as to be implausible to most of the reviewers at the journal Physical Review Letters.

    So the eternal and intrinsic helical motion of electrons in any state, including the ground state, is an established fact. How does that differ from the proposed time crystals?

    *[It seems to me that this actually makes time simpler – if both light and electrons are constrained to move at c, then time for either sort of particle, rather than being some mysterious quantity with a square opposite in sign to the other dimensions ( x^2 + y^2 +z^2 – (ct)^2 = 1 – (v/c)^2) ) becomes instead simply a distance, the hypotenuse in x^2 + y^2 +z^2 = ct^2. Also it should be noted that electrons can move in more complicated ways than single simple helices, and superpositions are possible. ] See Hestenes essayElectron time, mass and zitter at FQXi for more information.

  • I don’t get it. It seems to me, all he is saying is that large-scale periodic motions in a crystal can be quantized. That is to say, they behave in the same way as the internal modes of individual molecules regarding their exchange of energy with their environment. I wouldn’t have expected anything different. It seems to me a given. Crystals are really just huge molecules – at least that’s one way of viewing them.

    Now, the experimental effort to demonstrate such a thing is worthwhile.

  • As You break translational ( continuous) symmetry into discrete one, as in crystals, then You may get semiconductor. It is an material in which there is a gap in the energy spectrum  in the function of wavelength – or momentum – k.
    As article below says about famous Wilczek idea about time crystals, it is rather obvious to ask: if You break continues symmetry in time, what quantity will play a role as momentum above. I suppose it may be ( kinetic ? ) energy as a function of time. So not every pulsations ( frequencies) would be possible in such system?

    It means that  Is it “time semiconductor” possible?

  • @ Enon Harris: Thank you for your clarity of thought and the link to the Hestenes essay. I am gobsmacked. How did I ever miss zitter? Clearly, Wilczek, read it.

  • In response to Enon Harris in his question of what is new here, one word:

    Steven Hatton, you might expect quantized temporal scalability, but i’m not aware of this having yet been demonstrated.

    Should the experiment yield positive results, it would appear to lend support to the notion that time has an actual inherent presence in the scheme of things and not merely an emergent perceptual phenomenon. The experiment is expecting motion to arise as a function of time rather than the other way around. That issue remains a sizable foundational question.

  • ‘Time’ is a general concept related to the entire universe. Scientists may play around with it in whichever field they conceive but the fact remains the general perception and application remains. ‘Tinkering around the edges comes to mind’!

  • Don’t they already use crystals that naturally vibrate in a ground state as clocks for counters or frequency generators inside of microchips and computers? Seems like science needs a good kick in the pants to catch up to modern technology.

  • In reply to John “July 26, 2013”,
    Crystals vibrate/oscillate when a voltage source in applied to them.
    In other words a crystal’s ground state is static.

  • Charged particles in a state of accelerated motion dump electromagnetic radiation, called Larmor radiation. This has been well known for 100 years. A rotating ‘ring’ of calcium ions will dump EM radiation, i.e., EM energy because they are accelerating as they move about in a circle. This is due to centripetal acceleration. This example is no different than charged particles moving about in a particle accelerator. At very low velocities (relative to the speed of light) the type of radiation emitted is known as cyclotron radiation and the frequency (and energy) of the radiation is directly a function of rotation frequency. Physicists have worked out this problem long ago. Sorry folks, but that means there is an energy loss and that the particle must slow down.
    This notion of perpetual motion is whacky, but people keep trying to break the laws of thermodynamics. Good luck. The fellow who does gets the Nobel Prize.

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