March 15, 2018

Yesterday, March 14, famed British theoretical physicist Stephen Hawking died in Cambridge, England, at age 76. Hawking made some of the most important discoveries about gravity since Albert Einstein. Einstein, a German-born physicist, invented general relativity, the modern theory of gravity, in 1915. Hawking worked to increase our understanding of the earliest history of the universe. His work supported the theory that the universe began in a cosmic explosion called the big bang.

British theoretical physicist Stephen Hawking answers questions on a computer attached to his wheelchair during an interview in 2007. Hawking died on March 14, 2018. Credit: © John Raoux, AP Photo

Hawking is probably best known for his theories about objects called black holes. A black hole’s gravitational force is so strong that nothing—not even light—can escape it. Hawking used a field of physics called quantum mechanics to show that a black hole nevertheless gives off particles and radiation until it eventually disappears. These emissions became known as Hawking radiation. He also proposed that tiny, atom-sized primordial black holes were produced in the early moments after the big bang. In addition, Hawking worked to combine quantum mechanics and gravity into a single unified theory.

Three of Hawking’s books became international best sellers. They were A Brief History of Time: From the Big Bang to Black Holes (1988), The Universe in a Nutshell (2001), and The Grand Design (2010), which he co-wrote with American physicist Leonard Mlodinow. Following the success of A Brief History of Time, Hawking became a recognizable figure in popular culture, appearing in or lending his distinctive image and voice to various television shows. In 1991, American director Errol Morris made A Brief History of Time into an award-winning documentary film.

Hawking suffered from amyotrophic lateral sclerosis (ALS), an incurable disease of the nervous system. He could not speak or move more than a few hand and face muscles. Using a wheelchair and a computer voice simulator, however, he wrote and gave professional and public lectures around the world.

Hawking received numerous prestigious awards, including the Royal Society’s Copley Medal, the Gold Medal of the Royal Astronomical Society, and the American Presidential Medal of Freedom. He spoke on issues concerning science and society, such as genetic engineering, the colonization of space, and artificial intelligence.

Stephen William Hawking was born on Jan. 8, 1942, in Oxford, England. In 1966, he received a doctorate degree from Cambridge University. He afterward held a variety of research posts there. From 1979 to 2009, he held the prestigious position of Lucasian professor of mathematics at Cambridge, a chair once held by the English scientist and mathematician Sir Isaac Newton.

October 5, 2016

Yesterday, October 4, the Royal Swedish Academy of Sciences in Stockholm, Sweden, awarded the 2016 Nobel Prize in physics to three British scientists now working in the United States. David J. Thouless of the University of Washington in Seattle, F. Duncan M. Haldane of Princeton University, and J. Michael Kosterlitz of Brown University in Rhode Island shared the prize for their predictions on how matter reacts when pushed to its limits.

Nobel Prize medal (Credit: Nobel Foundation)

The physicists used topology to predict what happens to single-atom-thick films or chains at extremely low temperatures. Topology is a branch of mathematics that deals with properties of geometric figures that cannot be changed by stretching, squeezing, or twisting. Thouless, Haldane, and Kosterlitz created topological models to explain the strange behavior of these materials near absolute zero, the temperature at which atoms and molecules have the least amount of heat possible. Later researchers used complex laboratory techniques to confirm the predictions.

Far from being purely theoretical, the laureates’ work may eventually yield real-world dividends. Because their models accurately predict the behavior of exotic states of matter, engineers are exploring the possibilities of using such materials for applications in superconducters and quantum computers. Superconductors are materials that conduct electric current without resistance at extremely low temperatures. Quantum computers are machines that perform calculations by taking advantage of certain principles in quantum mechanics. Quantum computers can perform complex calculations that are practically impossible with traditional computers. The work of Thouless, Haldane, and Kosterlitz may well contribute to the next generation of advanced electronics.

October 9, 2012

The 2012 Nobel Prize in physics was awarded to American physicist David Wineland of the National Institute of Standards and Technology in Gaithersburg, Maryland, and the University of Colorado in Boulder and to French physicist Serge Haroche of the College de France and the Ecole Normale Superieure in Paris for their work in the field of quantum optics. Quantum optics is the study of how light as individual particles called photons interacts with matter.

The laws of physics used to describe and predict the behavior of objects that we  encounter in our daily lives were first described by the English scientist Sir Isaac Newton. These laws use such terms as force, velocity, and acceleration to describe the world around us. But extremely small particles seem to follow a different set of rules. These rules are called quantum mechanics. The rules of quantum mechanics deal with single atoms or even smaller particles called subatomic particles.

Many physicists had long believed that trapping and studying quantum particles was impossible. They had thought that simply studying quantum particles in an experiment would destroy the particles. However, Wineland and Haroche, working independently, were able to devise experiments that allowed them to isolate and study quantum particles without destroying them.

Magnesium ions appear in an ion trap, in a false-color image. As more ions are loaded into the trap, they squeeze closer together. (©Signe Seidelin and John Chiaverini/NIST)

Wineland was able to trap and study particles called ions (electrically charged atoms) by surrounding them with electric fields. The experiment is done at an extremely low temperature and in a vacuum (a space with little air or other matter). The scientists then fire a laser into the trap. This causes an ion to achieve a certain quantum state–being in two places at the same time. Haroche was able to trap and study photons using a set of two special mirrors. While the photon is bouncing between the mirrors, a single atom is placed into the same space. The interaction between the atom and the photon allows the particles to be studied.

The work done by Wineland has led to the development of a clock 100 times as accurate as the clock currently used as the standard. Scientists hope that both experiments have paved the way for the development of a quantum computer. This type of computer could use the ability of quantum particles to be in two places at the same time to run at speeds far beyond those of current computers. However, because quantum particles behave in such strange ways, controlling them is a major obstacle. These experiments may provide a step in overcoming this problem.