Monday, 19 May 2014

Scientists find way to turn light into matter

Researchers in London have found a way to make matter from light, using high powered lasers. The idea behind the theory was first thought up 80 years ago by two physicists, who were to work later on creating the world’s first atomic bomb. In 1934, US physicists Gregory Breit and John Wheeler worked out that, on very rare occasions, two particles
of light (photons) could combine to produce an electron and a positron. They were never able to carry out their theory in practice as they believed it would be almost impossible. However, Steve Rose, who is professor of physics at Imperial College London, says, “today, nearly 80 years later, we proved them wrong.” Rose went on to add, "despite all physicists accepting the theory to be true, when Breit and Wheeler first proposed the theory, they said that they never expected it be shown in the laboratory.” “What was so surprising to us was the discovery of how we can create matter directly from light using the technology that we have today in the UK. As we are theorists we are now talking to others who can use our ideas to undertake this landmark experiment,” Rose continued. They have managed to create a machine called a photon-photon collider, which would turn light into matter. However, the type of matter they are looking to create will be invisible to the naked eye. Oliver Pike, the lead researcher of the study, said that the experiment would be the most elegant demonstration of Einstein's famous formula. "The Breit-Wheeler process is the simplest way matter can be made from light and one of the purest demonstrations of E=mc2," he told The Guardian. The process works something like this. Firstly, the scientists would use an extremely powerful laser to speed up the electrons to travel almost at the speed of light. These electrons would then be fired at a slab of gold. This would create a beam of photons, which are a billion times more powerful than visible light. The next stage sees a high energy laser being fired into a hohlraum, which is the German for an ‘empty room.’ As a consequence, light as bright as that emitted by stars is produced and in the final stage, the first beam of the photons is directed towards the hohlraum, where the two streams collide, which forms electrons and positrons. The study has been published in the journal Nature Photonics. The scientists hope that the process will be demonstrated over the next 12 months, and if it is successful, it will encourage physicists to study how subatomic particles behave. Pike stated, "such a collider could be used to study fundamental physics with a very clean experimental setup: pure light goes in, matter comes out. The experiment would be the first demonstration of this.” The experiment would recreate a process that was important in the first 100 seconds of the universe and that is also seen in gamma ray bursts - the biggest explosions in the universe and one of the greatest unsolved mysteries of physics.