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(Phys.org)—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 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 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.

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Nice breakthrough.


Solution-processing methods are used to synthesize metal-oxide nanoparticle suspensions and thus realize efficient and stable devices.

Interfacial contact layers (ICLs) are thin films of semiconductors that can be inserted between the active organic layers and electrodes of organic photovoltaics (OPVs) to significantly improve the performance and stability of the devices. There are two types of ICL: hole transport layers (HTLs) and electron transport layers (ETLs) that require high-work-function p-type and low-work-function n-type semiconductors, respectively.1 As a result of these work-function requirements, a high built-in potential is established across the active layer of the OPV.1 In addition, specific carrier types can be chosen to reduce the amount of recombination in the devices (i.e., to block the minority carriers).1 To minimize losses from contact resistance and absorption, ICLs therefore need to be good electrical conductors and to be transparent to visible light.

Spider silk is well-known for its unusual combination of being both lightweight and extremely strong—in some cases, stronger than steel. Due to these properties, researchers have been developing spider-silk-inspired materials for potential applications such as durable yet lightweight clothing, bullet-proof vests, and parachutes.

But so far, the acoustic properties of spider webs have not yet been explored. Now in a new study, a team of researchers from Italy, France and the UK has designed an acoustic metamaterial (which is a material made of periodically repeating structures) influenced by the intricate spider web architecture of the golden silk orb-weaver, also called the Nephila spider.

“There has been much work in the field of metamaterials in recent years to find the most efficient configurations for wave attenuation and manipulation,” coauthor Federico Bosia, a physicist at the University of Torino in Italy, told Phys.org. “We have found that the spider web architecture, combined with the variable elastic properties of radial and circumferential silk, is capable of attenuating and absorbing vibrations in wide frequency ranges, despite being lightweight.”

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