Some of the most profound predictions in theoretical physics, such as Einstein’s gravitational waves or Higgs’ boson, have taken decades to prove with experiments. But every now and then, a prediction can become established fact in an astonishingly short time. This is what happened with “time crystals”, a new and strange state of matter that was theorized, disproved, revamped and finally created in just five years since it was first predicted in 2012.

Crystals, such as diamond and quartz, are made of atoms arranged in a repeating pattern in space. In these new crystals, atoms also follow a repeating pattern, but in time. Because of this weird property, time crystals could one day find applications in revolutionary technologies such as quantum computing.

The story of time crystals begins in 2012 with Nobel Prize winner Frank Wilczek from MIT. As a theoretical physicist and a mathematician, Wilczek made a crucial step in transferring a key property of regular crystals – called symmetry breaking – to create the idea of time crystals.

To understand what symmetry breaking is, think of liquid water. In a water droplet, molecules are free to move about and can be anywhere within the liquid. The liquid looks the same in any direction, meaning that it has a high degree of symmetry. If the water freezes to form ice, attractive forces between the molecules force them to rearrange into a crystal, where molecules are spaced at regular intervals. But this regularity means that the crystal isn’t as symmetrical as the liquid, so we say the symmetry of the liquid has been broken when freezing into ice.

Symmetry breaking is one of the most profound concepts in physics. It is behind the formation of crystals, but also appears in many other fundamental processes. For example, the famous Higgs mechanism, which explains how subatomic particles come to acquire mass, is a symmetry breaking process.

Back in 2012, Wilczek came up with a tantalizing idea. He wondered if, in the same way that a crystal breaks symmetry in space, it would be possible to create a crystal breaking an equivalent symmetry in time. This was the first time the idea of a time crystal was theorized.

Such an object would have intrinsic time regularity, equivalent to the crystal’s regular pattern in space. For a time crystal, the pattern would be a continuous change back and forth in one of its physical properties, a kind of heartbeat that repeats forever, a bit like a perpetual motion machine.

Perpetual motion machines, which are machines that can work indefinitely without an energy source, are forbidden by the laws of physics. Wilczek recognized this oddity of his time crystal theory and, in 2015, another group of theoretical physicists showed a perpetual motion crystal would indeed be impossible.

But this was not the end of the story. In 2016, new research showed that time crystals could still exist in theory, but only if there was some external driving force. The idea was that the time regularity would be somehow dormant, hidden from view, and that adding a little energy would bring it to life and unveil it. This solved the paradox of perpetual motion, and brought new hopes for the existence of time crystals.

Then, in the summer of 2016, the conditions to create and observe time crystals were laid out in an article in the online arXiv repository, and later published in the peer-reviewed journal Physical Review Letters. The researchers studied how a special property of particles known as quantum spin could be repeatedly reversed by an external force at regular intervals. They predicted that if they did this to a set of particles, the interactions between the particles would produce their own oscillations in the spin, creating a “driven” time crystal.

 Crystals have regular but asymmetrical atomic arrangements. Shutterstock/SmirkDingo

In a matter of months, two different experimental groups had taken on the challenge to create the time crystals in the laboratory. One of the teams fired laser pulsesat a train of ytterbium atoms that produced oscillations in the atoms’ properties, at different intervals from the pulses. This meant that the ytterbium atoms were behaving as a time crystal.

The other team focused on an entirely different system, consisting of impurities in a diamond crystal. They used microwaves to disturb the impurities at well-defined intervals, and observed the same type of time-crystal oscillations as the first team. At last, time crystals had been created and Wilczek’s main ideas proven true.

The prediction, realization and discovery of time crystals opens a new chapter in quantum mechanics, with questions about the properties of this newly found state of matter and whether time crystals might occur in nature.

The symmetry-breaking properties of ordinary crystals have led to the creation of phononic and photonic metamaterials, deliberately designed materials that selectively control acoustic vibrations and light that can be used to boost the performance of prosthetics, or to increase the efficiency of lasers and fibre-optics. So the time symmetry-breaking properties of time crystals will likely find their way into equally novel fields, such as chrono-metamaterials for quantum computing, which uses the inherent properties of atoms to store and process data.

The story of time crystals started with a beautiful idea by a theoretical physicist, and now has culminated its first chapter with conclusive experimental evidence after a mere five years. Far from coming to an end as scientists prove their big theories, it seems physics is more alive than ever.

Rodrigo Ledesma-Aguilar, Senior Lecturer in Physics, Northumbria University, Newcastle

This article was originally published on The Conversation. Read the original article.

Cosmologists from Britain are confused: they guess that the universe should not have lasted for more than a second. This surprising assumption is the outcome of merging the newest interpretations of the sky with the latest discovery of the Higgs boson. 

According to Robert Hogan of King's College London (KCL), who presented the new research at the Royal Astronomical Society's National Astronomy Meeting. After the Universe created in the Big Bang, it is supposed to have moved out over a short period of quick expansion known as 'cosmic inflation'. 

Even though the details of this procedure are not yet completely understood, cosmologists have been able to make predictions of how this would affect the Universe we understand currently. Scientists from the BICEP2 collaboration claimed to have identified one of these projected effects. If correct, their outcomes are a major development in our understanding of cosmology and a validation of the inflation theory, but they have proven debatable and are not yet completely acknowledged by cosmologists. 

In the new study, researchers from KCL have studied what the BICEP2 interpretations mean for the constancy of the Universe. To do this, they joined the outcomes with new developments in particle physics. The discovery of the Higgs boson by the Large Hadron Collider was proclaimed in July 2012; ever since, much has been understood about its properties. Measurements of the Higgs boson have permitted particle physicists to display that our universe lies in a valley of the 'Higgs field', which defines the way that other particles have mass. Though, there is a dissimilar valley which is far deeper, but our universe is avoiding from sinking into it by a huge energy barrier. The difficulty is that the BICEP2 outcomes forecast that the universe would have received huge 'kicks' during the cosmic inflation stage, pushing it into the additional valley of the Higgs field in a fraction of a second. If that had occurred, the universe would have rapidly shrunken in a BigCrunch.

"This is an unacceptable prediction of the theory because if this had happened we wouldn't be around to discuss it" said Hogan, who is a PhD student at KCL and led the study. "If BICEP2 is shown to be correct, it tells us that there has to be interesting new particle physics beyond the standard model" Maybe the BICEP2 outcomes comprise an error. If not, there has been some other, as yet unknown, procedure which stopped the universe from collapsing.

Credit:  Royal Astronomical Society

Article was originally published on DailyGalaxy.

Most familiar lepton is electron. Three Leptons have charge and these are Electron, Muon and Tau. The other three are neutral and are called neutrinos. These are Electron neutrino, Muon neutrino, Tau neutrino. Quarks and Lepton make every particle that we know. Quarks and Leptons are the building blocks of the Cosmos. These quarks and Leptons are held together to form other particle due to different forces. Without these forces, these particles will not interact with each other. Physicists know about four kinds of forces, Gravity, Electromagnetism, Strong nuclear force and Weak force. Gravity is the most common force and in quantum realm Gravity is a weak force and physicists don’t know how it works in the quantum realm. Other three are very well understood. Forces of Gravity and Electromagnetism have effects on large distances and scales while other two only have effect in atomic level. All the subatomic forces work by exchanging different kind of particles. Gluons are force partcles for the strong nuclear force, Photons are force particles for the electromagnetic force and W and Z bosons are for weak nuclear force. In Standard model Gravity is not counted. In Standard Model Higgs Boson is a particle of Higgs Field and fermions describes the excitations of fermionic fields.

Well, getting back to Higgs Boson. Some atomic particles have a great deal of mass and some have a little while some have not at all. Energy field proposed by Peter Higgs would interact with subatomic particles and will give them a certain amount of mass. Particle with great mass will interact a lot with the Higgs field. The lighter subatomic particle is Electron and king of mass is Top Quark. Top Quark is thousand times massive than electrons. The top quark and electron are of same size indeed they have zero size. Top quark interacts more with Higgs Field than electron and that is why it is more massive. No Higgs field means any mass of any particle. The Higgs Boson is the smallest bit of Higgs Field. Higgs Field is made of countless individual particles of the Higgs Boson particles. This is why most of the time Higgs Boson is also known as "The God Particle". Higgs field actually decides which particle will be more massive than others and that is why it is important concept in the Standard Model.