“The crystals of time” can turn theoretical physics




“The crystals of time” can turn theoretical physics

In February 2012, the Nobel Prize-winning physicist Frank Wilczek, he decided to go public with the strange and, as it seemed a little awkward assumption. Impossible in his idea was that Wilczek has designed and developed a proof of the existence of “time crystals” – physical structures that move along the same lines as the moment in hours, not expending energy and never stopping. Unlike hours and any other known objects crystals obtained time no energy for movement of the storage of a fault in the time symmetry, which is a special form of a perpetual motion.

“Most of the research in physics are the continuation of the things that have been done earlier,” – says Wilczek, a professor at the Massachusetts Institute of Technology. According to him, the need to “look out of the box.”

The idea of ​​Wilczek physics met with suspicion. On the one hand, we have a brilliant professor, known for the development of exotic theories, which are then entered into the mainstream, for example, the existence of particles called axions and anions, as well as the observed properties of nuclear forces, known as asymptotic freedom (for which he received the Nobel Prize in Physics in 2004). On the other hand, he speaks of the eternal movement, which is considered impossible because of the fundamental laws of physics, which are hard to get around. Does his work became the greatest breakthrough or just a logical fallacy? Jakub Zakrzewski, a professor of physics and head of the atom optics at the Jagiellonian University in Poland, studied research Wilczek said simply:

“I do not even know.”

Fortunately, technological advances have made it possible to test this idea. Physicists plan to build crystals of time, not even for the fact that they will generate an infinite amount of energy (and thus become a perpetual motion machine, which tried unsuccessfully to create thousands of years), and for the fact that the finding could tell that this time at the case.

The idea was born in Wilczek, when he was preparing a lecture in 2010:

“I was thinking about the classification of crystals, and then it dawned on me that you might think of space-time from this point of view. And as you think about the crystals in space, it is natural to think about the behavior of the crystalline forms of the time. ”

When matter is crystallized, its atoms spontaneously line up in rows, columns, and stacks of three-dimensional lattice. Atom occupies the position in the lattice, but the balance of forces between the atoms prevents them crowd into the space. Because the atoms have discrete rather than continuous selection of places to appear, the crystals break spatial symmetry of nature – the usual rule that all places in space are equivalent. But what about the time symmetry of nature – the rule that stable objects remain unchanged over time?

Wilczek pondered this for a few months. In the end, his equations showed that atoms can indeed form a repeating lattice constant in time, going back to its original position after a discrete (not continuous) interval, thus breaking the time symmetry. Without consumption or energy production timing crystals are stable, that is, in the “ground state” as physicists say, despite the cyclical changes in the structure of that from the point of view of physics can be described as perpetual motion.

“In physics will be absolute madness to think of the ground state as the time-dependent” – says Hartmut Haffner, a quantum physicist at Caltech. – “The definition of the ground state, it follows that its energy is equal to zero. But if the state is independent of the time, this implies that either the energy changes, or something else. Something is moving in a circle. ”

How can anything can go forever without wasting energy? It sounds crazy, because it contradicts the conventional laws of physics. But research Wilczek on the quantum and classical crystals of time (the latter – in collaboration with Alfred Schaper from the University of Kentucky) were tested experts and have been published in Physical Review Letters in October 2012. Wilczek does not claim to know whether objects that violate the symmetry of time, exist in nature, but he will try to do one of those in the experiment.

“Imagine that you are drawing a target and wait for it to fall boom. Because there is no logical contradiction in the fact that this can happen, I think it’s going to happen. ”


Франк Вилчек

Frank Wilczek.

In June, a group of physicists led by Xiang Zhang, a nano-engineer from Berkeley, and Tongchanga Lee, a physicist from Zhang’s group, proposed the creation of the crystals in the form of time constantly rotating rings of charged atoms, or ions. (Lee said that he thought about it before I read the documentation Wilczek). The article was published with vilchekovskoy in the same journal.

Since then, only one critic – Patrick Bruno, a theoretical physicist at the European Synchrotron Radiation Facility in France – has expressed disagreement in the scientific way. Bruno believes that Wilczek and his colleagues mistakenly equate time-dependent behavior of objects with an excited energy state, and not the main one. There is nothing surprising in the objects with excess energy movement in the cycle with a slowing of movement as the dissipation of energy. To become crystal-time, the object must have the perpetual motion in the ground state.

Comment by Bruno and answer Wilczek appeared in the Journal of PRL in March 2013 year. Bruno showed that the lowest energy state is possible in the system proposed by Wilczek, as a hypothetical example of a quantum crystal of time. Wilczek replied that although this example is not a crystal of time, he does not think that this error “calls into question the basic concepts.”

“I have proved that the example is incorrect. But I still do not have a general proof. So far. ”

The debate is hardly run the theoretical bases. Trump card in the hands of experimentalists.

An international team of researchers led by scientists at Berkeley prepares complex experiment in the laboratory, but it can be carried out in the period of “three years to infinity” before coming to a logical conclusion. It all depends on unforeseen technical difficulties or financing. The hope is that time will lead crystal physics beyond accurate, but still imperfect quantum mechanics, and pave the way for a great theory.

“I’m very interested in seeing if I can make a contribution, following the postulates of Einstein,” – says Lee. – “He said that quantum mechanics is incomplete.”

Ion ring

Ионное кольцо

Vector experiment ring of magnetically trapped ions.

In Einstein’s theory of general relativity, measurements of space and time are woven together – the space-time. But in quantum mechanics, which is responsible for the interaction of matter at the subatomic level, the time is different – “panic, aesthetically unpleasant,” according to Zakrzewski.

The different concept of time can be one of the reasons of incompatibility of general relativity and quantum mechanics. At least one of these two elements should be changed to make possible the establishment of a comprehensive theory of quantum gravity. This is one of the main goals of theoretical physics. Which of the concept of time is correct?

If time crystals can break the symmetry of time in the same manner as conventional crystals break spatial symmetry “This is to say that the nature of these two values ​​seem to have balanced properties, and hence should be clearly recognized in theory. This means that quantum mechanics is imperfect, and quantum physicists have to consider the time and space as the two strands of the same fabric.

Berkeley command will try to build time crystals by introducing calcium ions into hundreds of small chamber surrounded by electrodes. The electric field will drive the ions in the trap of a thickness of 100 microns, about a human hair. After the scientists will have to calibrate the electrodes to align the field. Since the charges repel each other, the ions are distributed uniformly over the outer edge of the trap, forming a crystal ring.

First, the ions will vibrate in an excited state, but diode lasers, such as those used in DVD-players, will cut back on their kinetic energy. According to the calculations of, ion ring to reach the ground state when the lasers cool the ions to a billionth of a degree above absolute zero. This temperature has long been unattainable due to heating of the electrodes in the trap, but in September there was a revolutionary technology, which is a hundred times will reduce the thermal background of the trap. This is the factor that is needed to researchers.

The researchers then include a static magnetic field in the trap, which, according to theory, force the ions to rotate (and up to infinity). If all goes according to plan, the ions return to the starting point after a certain period of time, forming a regularly recurring time grid and time symmetry breaking.

To see the rotation of the ring, the researchers moved by one of the ions with a laser, effectively putting it in another electronic state than the other 99 ions. Elect ion will remain bright and demonstrate a new location, while others will darken the second laser.

If the bright ion will handle a constant rate, the researchers first demonstrate that the translational symmetry of time can be broken.

“It’s really revolutionize our understanding,” – says Lee. But first we have to prove that it works. ”

While the experiment is completed successfully, many physicists are skeptical.

“Personally, I think it is impossible to detect the motion in the ground state,” – says Bruno. – “They can drive the ring of ions in a toroidal trap and play with interesting physics, but they do not see their clock is ticking all the time, as they say.”

Although, who knows, maybe quantum mechanics is not so bad .
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