Researchers have worked out how to make matter from pure light and are drawing up plans to demonstrate the feat within the next 12 months. 
 
 The theory underpinning the idea was first described 80 years ago by two physicists who later worked on the first atomic bomb. At the time they considered the conversion of light into matter impossible in a laboratory. 
 
 But in a report published on Sunday, physicists at Imperial College London claim to have cracked the problem using high-powered lasers and other equipment now available to scientists. 
 
 "We have shown in principle how you can make matter from light," said Steven Rose at Imperial. "If you do this experiment, you will be taking light and turning it into matter." 
 
 The scientists are not on the verge of a machine that can create everyday objects from a sudden blast of laser energy. The kind of matter they aim to make comes in the form of subatomic particles invisible to the naked eye. 
 
 The original idea was written down by two US physicists, Gregory Breit and John Wheeler, in 1934. They worked out that – very rarely – two particles of light, or photons, could combine to produce an electron and its antimatter equivalent, a positron. Electrons are particles of matter that form the outer shells of atoms in the everyday objects around us. 
 
 But Breit and Wheeler had no expectations that their theory would be proved any time soon. In their study, the physicists noted that the process was so rare and hard to produce that it would be "hopeless to try to observe the pair formation in laboratory experiments". 
 
 Oliver Pike, the lead researcher on the study, said the process was one of the most elegant demonstrations of Einstein's famous relationship that shows matter and energy are interchangeable currencies. "The Breit-Wheeler process is the simplest way matter can be made from light and one of the purest demonstrations of E=mc2," he said. 
 
 Writing in the journal Nature Photonics, the scientists describe how they could turn light into matter through a number of separate steps. The first step fires electrons at a slab of gold to produce a beam of high-energy photons. Next, they fire a high-energy laser into a tiny gold capsule called a hohlraum, from the German for "empty room". This produces light as bright as that emitted from stars. In the final stage, they send the first beam of photons into the hohlraum where the two streams of photons collide. 
 
 The scientists' calculations show that the setup squeezes enough particles of light with high enough energies into a small enough volume to create around 100,000 electron-positron pairs. 
 
 The process is one of the most spectacular predictions of a theory called quantum electrodynamics (QED) that was developed in the run up to the second world war. "You might call it the most dramatic consequence of QED and it clearly shows that light and matter are interchangeable," Rose told the Guardian. 
 
 The scientists hope to demonstrate the process in the next 12 months. There are a number of sites around the world that have the technology. One is the huge Omega laser in Rochester, New York. But another is the Orion laser at Aldermaston, the atomic weapons facility in Berkshire. 
 
 A successful demonstration will encourage physicists who have been eyeing the prospect of a photon-photon collider as a tool to study how subatomic particles behave. "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," Pike said. 
 
 Andrei Seryi, director of the John Adams Institute at Oxford University, said: "It's breathtaking to think that things we thought are not connected, can in fact be converted to each other: matter and energy, particles and light. Would we be able in the future to convert energy into time and vice versa?" ||||| The dark side of the universe is whispering, but scientists are still not sure what it is saying. 
 
 Samuel Ting, a professor at the Massachusetts Institute of Technology and a Nobel laureate particle physicist, said Wednesday that his $1.6 billion cosmic ray experiment on the International Space Station had found evidence of “new physical phenomena” that could represent dark matter, the mysterious stuff that serves as the gravitational foundation for galaxies and whose identification would rewrite some of the laws of physics. 
 
 The results, he said, confirmed previous reports that local interstellar space is crackling with an unexplained abundance of high energy particles, especially positrons, the antimatter version of the familiar electrons that comprise electricity and chemistry. They could be colliding particles of dark matter. Or they could be coming from previously undiscovered pulsars or other astronomical monsters, throwing off wild winds of radiation. 
 
 The tantalizing news is that even with the new data, physicists cannot tell yet which is the right answer, but they are encouraged that they soon might be able to. 
 
 “I don’t think it makes you believe it must be dark matter, nor do I think it makes you believe it cannot be,” said Neal Weiner, a particle theorist at New York University. 
 
 The good news is that the Alpha Magnetic Spectrometer, as Dr. Ting’s instrument is called, is only two years into what could be a 20-year voyage on the space station, and is working brilliantly. “Over the coming months, A.M.S. will be able to tell us conclusively whether these positrons are a signal for dark matter, or whether they have some other origin,” Dr. Ting told an audience of physicists at CERN, the European Organization for Nuclear Research. 
 
 The report will be published in Physical Review Letters on Friday. 
 
 Astronomers and others from outside the collaboration responded enthusiastically. 
 
 “A.M.S. has confirmed with exquisite precision and to high energy one of the most exciting mysteries in astrophysics and particle physics,” said Justin Vandenbroucke of the University of Wisconsin and Stanford’s SLAC laboratory. 
 
 Maria Spiropulu, a Caltech particle physicist, said, “They have exquisitely small errors and they stop the plot at the cliffhanger, so we will be asking for more.” 
 
 Others, like Gregory Tarle of the University of Michigan, cautioned that uncertainties in the galactic background of radiation might make it impossible to ever get a clean answer to the source of the positrons. 
 
 Dark matter has teased and obsessed astronomers since the 1930s, when the Caltech astronomer Fritz Zwicky deduced that some invisible “missing mass” was required to supply the gravitational glue to hold clusters of galaxies together. 
 
 According to recent measurements by the Planck spacecraft, about 27 percent of the universe, by mass, is composed of some unknown form of matter unlike the atoms that make up us and everything we can see. Astronomers cannot see it, but they can detect its gravitational tug pulling the galaxies and stars around. 
 
 Figuring out what this stuff is is important for more than cosmology. The most favored candidates for its identity are as yet undiscovered particles known as WIMPs — weakly interacting massive particles — left over from the Big Bang. Such particles could drift through the Earth like wind through a screen door. Impervious to almost everything except gravity, they would form a shadow universe clumping together into invisible clouds that then attract ordinary matter. Discovering one of them could give a lift to new theories of physics, like supersymmetry, which predicts of a whole new spectrum of so-called superpartners to the particles we already know about, not to mention explicating the nature of more than a quarter of creation. 
 
 But until now, the dark matter particles have mostly eluded direct detection in the laboratory or creation at the Large Hadron Collider. 
 
 The sky could be a different story. Such WIMPs floating in the halos around galaxies would occasionally collide and annihilate one another in tiny fireballs of radiation and lighter particles, the theorists Michael Turner of the University of Chicago and Frank Wilczek of M.I.T. suggested in 1990.
– Scientists are on the brink of turning light into matter—a process first theorized in 1934 but then described by the very men behind the idea as "hopeless to try." The subatomic particles the Imperial College London physicists say they've figured out how to produce will not be visible to the naked eye, but will be "one of the purest demonstrations of E=mc2," Einstein’s famous equation describing the "interchangeable" relationship between mass and energy, the Guardian reports. They think they can attempt the feat in the next 12 months using existing technologies. What'll happen in general: Two particles of light (photons) will be smashed together to create an electron-positron pair, known as a Breit-Wheeler pair in honor of the earlier researchers, Americans Gregory Breit and John Wheeler. The specifics of the process: First a stream of electrons will be fired into a slab of gold, creating a high-energy photon beam; then, a high-energy laser will be fired into a gold can called a hohlraum, creating light akin to what stars emit. The first beam will then be directed into the center of the can, and the two photon sources will collide. What emerges from the can: electrons and positrons. It is "a very clean experiment: pure light goes in, pure matter comes out. This experiment would be the first demonstration of this,” says physicist Oliver Pike. In a letter about their plans published in Nature Photonics, Pike and his colleagues say they are ushering in "the advent of a new type of high-energy physics experiment." (Click to read about another big discovery.)