All posts by Daniel Davies

Researchers discover particles missed in quantum theory’s development

A particle missed during the initial development of quantum theory has been found thanks to researchers’ exploration of the “material universe” .

An international team of researchers have theorised that a particle, called the type-II Weyl fermion, exists in a material known as tungsten ditelluride (WTe2), which the researchers liken to a “material universe” because it contains several particles, some of which exist under normal conditions in our universe and others that may exist only in specialized types of crystals.

These crystals can be grown in the laboratory, so experiments can be done to look for the newly predicted Weyl fermion in WTe2 and another candidate material, molybdenum ditelluride (MoTe2).

Image courtesy of B. Andrei Bernevig et al

Image courtesy of B. Andrei Bernevig et al

“Even more intriguing is the perspective of finding more ‘elementary’ particles in other condensed matter systems,” the researchers say.

“What kind of other particles can be hidden in the infinite variety of material universes? The large variety of emergent fermions in these materials has only begun to be unravelled.”

The researchers assume that the particle’s existence was missed by physicist Hermann Weyl, during the initial development of quantum theory 85 years ago, because it violated a fundamental rule called Lorentz symmetry that does not apply to the materials where the new type of fermion arises from.

In recent years, researchers have discovered that such a “material universe” could host all other particles of relativistic quantum field theory. Three quasiparticles, the Dirac, Majorana and Weyl fermions, were discovered in such materials, despite the fact that the latter two had long been elusive in experiments.

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“One’s imagination can go further and wonder whether particles that are unknown to relativistic quantum field theory can arise in condensed matter,” says Princeton University associate professor of Physics B Andrei Bernevig.

“One may wonder,” Soluyanov said, “if it is possible that some material universes host non-relativistic ‘elementary’ particles that are not Lorentz-symmetric?”

The existence of the type-II Weyl fermion and the behaviour it exhibits suggests a range of potential applications, from low-energy devices to efficient transistors.

The full version of the researchers’ findings – Type II Weyl Semimetals – can be found in the journal Nature.

Eliminate air pollution and emissions by storing energy underground: Stanford researcher

A Stanford researcher has suggested that storing energy generated from wind, water and solar power underground may be the key to moving to renewable energy while maintaining consumer demand.

In a new study published in Proceedings of the National Academy of Sciences, Mark Jacobson has proposed storing heat, gathered from rooftop solar collectors, in soil or rocks so that it can be used later for heating homes.

In Jacobson’s plan, hydrogen would be used as a storage medium, with excess electricity used to create hydrogen, which could be stored in fuel cells and used to power some vehicles. Electricity could also be used to make ice, which would be used for later cooling, especially when the price of electricity is high.

Featured image courtesy of Justin Elliott

Featured image courtesy of Justin Elliott

Jacobson has stressed that there are numerous benefits to shifting to renewable sources of energy.

He said:  “You eliminate air pollution and global warming emissions, stabilize fuel costs, create over two million more jobs that are lost in the US, you reduce reliance on international trade of fuels, and you reduce the risk of power disruption, such as from terrorism or massive failure, because more energy is distributed over larger areas.

“Most energy would be local. You can eliminate a lot of fuel emissions, just because you won’t have to transport oil in tankers across the ocean, you won’t have to use trains of coal cars to ship the coal.”

Jacobson’s new model is dependent upon an all-electric country, with virtually everything running on electricity. So cars, trains, buses, industry, heating and cooling would be powered with the electricity that is gathered from wind, water and sunlight.

There would be no need for coal, natural gas, biofuels, nuclear power or enormous battery farms to store electricity.

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Previous studies by Jacobson have drawn widespread attention, but critics have argued that a national electric grid without the backup of coal and natural gas to fill gaps in supply would not be reliable. After all, the wind doesn’t always blow and the sun doesn’t always shine, and batteries for the grid are not yet affordable enough for storing and managing the nation’s electricity.

“The utilities and others who are against renewables have always argued that the lights are going to go out, the grid is going to be unstable, and it will cost too much to keep a clean, renewable-energy grid stable and reliable,” Jacobson said.

“Skeptics have never studied a system of 100% clean, renewable energy for all purposes, and particularly one that combines low-cost storage with demand response and some hydrogen, as in this new paradigm.”

Read more about the future of energy in Issue 18 of Factor