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AS MISMATCHES go, it’s a big one. When physicists bring the Standard Model of particle physics and Einstein’s general theory of relativity together they get a clear prediction. In the very early universe, equal amounts of matter and antimatter should have come into being. Since the one famously annihilates the other, the result should be a universe full of radiation, but without the stars, planets and nebulae that make up galaxies. Yet stars, planets and nebulae do exist. The inference is that matter and antimatter are not quite as equal and opposite as the models predict.

This problem has troubled physics for the past half-century, but it may now be approaching resolution. At CERN, a particle-physics laboratory near Geneva, three teams of researchers are applying different methods to answer the same question: does antimatter fall down, or up? Relativity predicts “down”, just like matter. If it falls up, that could hint at a difference between the two that allowed a matter-dominated universe to form.

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The study of the subatomic world has revolutionized our understanding of the laws of the universe and given humanity unprecedented insights into deep questions. Historically, these questions have been in the philosophical realm: How did the universe come into existence? Why is the universe the way it is? Why is there something, instead of nothing?

Well, move over philosophy, because science has made a crucial step in building the equipment that will help us answer questions like these. And it involves shooting ghostly particles called neutrinos literally through the Earth over a distance of 800 miles (nearly 1,300 kilometers) from one physics lab to another.

An international group of physicists has announced that they have seen the first signals in a cube-shaped detector called ProtoDUNE. This is a very big stepping stone in the DUNE experiment, which will be America’s flagship particle physics research program for the next two decades. ProtoDUNE, which is the size of a three-story house, is a prototype of the much larger detectors that will be used in the DUNE experiment and today’s (Sept. 18) announcement demonstrates that the technology that was selected works. [The 18 Biggest Unsolved Mysteries in Physics].

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Electrons tend to avoid one another as they go about their business carrying current. But certain devices, cooled to near zero temperature, can coax these loner particles out of their shells. In extreme cases, electrons will interact in unusual ways, causing strange quantum entities to emerge.

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It’s not easy being a “theory of everything.” A TOE has the very tough job of fitting gravity into the quantum laws of nature in such a way that, on large scales, gravity looks like curves in the fabric of space-time, as Albert Einstein described in his general theory of relativity. Somehow, space-time curvature emerges as the collective effect of quantized units of gravitational energy — particles known as gravitons. But naive attempts to calculate how gravitons interact result in nonsensical infinities, indicating the need for a deeper understanding of gravity.

String theory (or, more technically, M-theory) is often described as the leading candidate for the theory of everything in our universe. But there’s no empirical evidence for it, or for any alternative ideas about how gravity might unify with the rest of the fundamental forces. Why, then, is string/M-theory given the edge over the others?

The theory famously posits that gravitons, as well as electrons, photons and everything else, are not point-particles but rather imperceptibly tiny ribbons of energy, or “strings,” that vibrate in different ways. Interest in string theory soared in the mid-1980s, when physicists realized that it gave mathematically consistent descriptions of quantized gravity. But the five known versions of string theory were all “perturbative,” meaning they broke down in some regimes. Theorists could calculate what happens when two graviton strings collide at high energies, but not when there’s a confluence of gravitons extreme enough to form a black hole.

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Japan’s government is facing serious fiscal challenges, but its main science ministry appears hopeful that the nation is ready to once again back basic research in a big way. The Ministry of Education (MEXT) on 31 August announced an ambitious budget request that would allow Japan to compete for the world’s fastest supercomputer, build a replacement x-ray space observatory, and push ahead with a massive new particle detector.


Proposed successor to Super-Kamiokande, exascale computer and x-ray satellite win backing.

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TRULY SUPER. There’s a reason researchers call graphene a “super material.” Even though it’s just a single layer of carbon atoms thick, it’s super strong, super flexible, and super light. It also conducts electricity, and is biodegradable. Now an international team of researchers has found a way to use the super material: to create artificial retinas.

They presented their work Monday at a meeting of the American Chemical Society (ACS).

ARTIFICIAL RETINAS. The retina is the layer of light-sensitive cells at the back of the eye responsible for converting images into impulses that the brain can interpret. And without a functional one, a person simply can’t see.

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The giant CMS detector at the Large Hadron Collider will search for double-Higgs events.

IMAGE: MICHAEL HOCH AND MAXIMILIEN BRICE

For particle physicists eager to explore new frontiers, spotting the Higgs boson has become a bittersweet triumph. Detected in 2012 at the world’s biggest atom smasher, the Large Hadron Collider (LHC), the long-sought particle filled the last gap in the standard model of fundamental particles and forces. But since then, the standard model has stood up to every test, yielding no hints of new physics. Now, the Higgs itself may offer a way out of the impasse. Experimenters at the LHC, located at CERN, the European particle physics laboratory near Geneva, Switzerland, plan to hunt for collisions that produce not just one Higgs boson, but two.

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Quantum particles can be difficult to characterize, and almost impossible to control if they strongly interact with each other—until now.

An international team of researchers led by Princeton physicist Zahid Hasan has discovered a state of matter that can be “tuned” at will—and it’s 10 times more tuneable than existing theories can explain. This level of manipulability opens enormous possibilities for next-generation nanotechnologies and quantum computing.

“We found a new control knob for the quantum topological world,” said Hasan, the Eugene Higgins Professor of Physics. “We expect this is tip of the iceberg. There will be a new subfield of materials or physics grown out of this. … This would be a fantastic playground for nanoscale engineering.”

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Graphene — an ultrathin material consisting of a single layer of interlinked carbon atoms — is considered a promising candidate for the nanoelectronics of the future. In theory, it should allow clock rates up to a thousand times faster than today’s silicon-based electronics. Scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) and the University of Duisburg-Essen (UDE), in cooperation with the Max Planck Institute for Polymer Research (MPI-P), have now shown for the first time that graphene can actually convert electronic signals with frequencies in the gigahertz range — which correspond to today’s clock rates — extremely efficiently into signals with several times higher frequency. The researchers present their results in the scientific journal Nature.

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