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Graphene—a superstrong, transparent, conductive material made up of a single layer of carbon atoms—nabbed the 2010 Nobel Prize for the physicists who isolated it. And no wonder: The material has the potential to revolutionize electronics if it can be produced in sufficient size and quantity. Last June researchers in South Korea, Japan, and Singapore announced a major step in that direction.
The Big Bang theory has a Big Problem. The leading models of cosmology imply that the universe should have begun with equal quantities of matter and antimatter. But when the two meet, they annihilate each other, so an equal balance would have yielded an empty cosmos. In May, physicists at the Tevatron particle accelerator in Illinois singled out a strange particle that could help explain the conundrum. Studying nearly eight years’ worth of high-speed smashups between protons and antiprotons, Guennadi Borissov of Lancaster University in the U.K. and other members of the Tevatron team focused on the B meson, a short-lived particle that emerges from the collisions.
In May an international group of physicists studying the elusive particles known as neutrinos announced that they had spotted one spontaneously transforming from one type to another . Such an ability indicates that neutrinos, long thought to be weightless, have mass, a finding with profound theoretical and cosmological implications. Neutrinos come in three varieties: muon, tau, and electron.
Few things in physics have been more thoroughly studied than the proton, a fundamental building block of atoms. So it was a shock in July when Paul Knowles of the University of Fribourg in Switzerland claimed the proton is 4 percent smaller than everyone has thought for more than 50 years. In the past, physicists have used electrons to measure the proton’s size indirectly. When a laser zaps an electron orbiting a proton, the electron undergoes what is called the Lamb shift, absorbing energy and jumping to a higher energy level. According to quantum electrodynamics, the Lamb shift is partly a function of the proton’s size; this allows physicists to infer its measurements. But instead of lasing electrons, Knowles examined protons with particles called muons, which he calls “the electron’s fat cousin.”
In a quantum field theory , charge screening can restrict the value of the observable "renormalized" charge of a classical theory.
In physical cosmology and astronomy , dark energy is a hypothetical form of energy that permeates all of space and tends to accelerate the expansion of the universe . [ 1 ] Dark energy is the most accepted hypothesis to explain observations since the 1990s that indicate that the universe is expanding at an accelerating rate .
The holographic principle is a property of quantum gravity and string theories which states that the description of a volume of space can be thought of as encoded on a boundary to the region—preferably a light-like boundary like a gravitational horizon . First proposed by Gerard 't Hooft , it was given a precise string-theory interpretation by Leonard Susskind [ 1 ] who combined his ideas with previous ones of 't Hooft and Charles Thorn . [ 1 ] [ 2 ] As pointed out by Raphael Bousso , [ 3 ] Thorn observed in 1978 that string theory admits a lower dimensional description in which gravity emerges from it in what would now be called a holographic way.
Entropic gravity is a hypothesis in modern physics that describes gravity as an entropic force ; not a fundamental interaction mediated by a quantum field theory and a gauge particle (like photons for the electromagnetic force , and gluons for the color force ), but a probabilistic consequence of physical systems' tendency to increase their entropy .
Loop quantum gravity ( LQG ) is a theory that attempts to describe the quantum properties of gravity .