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E = light = mc[SUP]2[/SUP] = stuff!

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  • E = light = mc[SUP]2[/SUP] = stuff!

    So those damned scientists are going to take light and turn it into matter.

    It's a world gone mad.

    Matter will be created from light within a year, claim scientists
    In a neat demonstration of E=mc2, physicists believe they can create electrons and positrons from colliding photons

    Ian Sample, science correspondent
    The Guardian, Sunday 18 May 2014 13.00 EDT


    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?"
    So within a year, these quantum electrondynamics folk will be gleefully pointing at something invisible and saying, "See? QED!"

    In a neat demonstration of E=mc2, physicists believe they can create electrons and positrons from colliding photons


    Note: I'm also officially bummed that superscript didn't work in the thread title.
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  • #2
    I was under the impression that this kind of thing happened all the time during the chaos that is accelerator collisions. It's very possible my impression is wrong, though.
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    • #3
      Replicators aren't that far behind. But can you replicate the human soul?
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      • #4
        No, we'll be stuck with nothing but golems. Monstrous, bloodthirsty, golems.
        John Brown did nothing wrong.

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        • #5
          Lorizael - particle accelerators collide matter against matter. Specifically certain atomic and subatomic particles. It's easier to do and to manage because they are much larger than photons. They also don't have a rest velocity.

          It's really no different than a kid ramming two toy cars together.

          This? Well, Photons are small. They also travel faster than anything else. So you can't really slow them down (well, unless you use certain mediums, and even then it's not going to go slow enough for easy manipulation). That's why they are going to use these streams, on the offhand chance that they saturate the (very small), area with sufficient photons to trigger collisions. It's really hard to do because photons are so small and fast and you are crashing them into each other. That's why it's not been done before - you have to saturate a specific cross section with an absolutely ridiculous number of photons in the hopes that you get just one collision.

          Basically, they are shining two really bright beams through tiny slits into a mirrored breadbox. As they continue to pump light into it, the photon density increases.

          I suppose I could do the calculations to figure out just how many photons, but suffice to say, they'd need more photons to fill an area the size of a breadbox than grains of sand in all the beaches of the universe.

          This would be like shining a really bright light into your Mr. Fusion and getting the can you dumped in, back.
          Last edited by Ben Kenobi; May 20, 2014, 00:09.
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          • #6
            Originally posted by DaShi View Post
            Replicators aren't that far behind. But can you replicate the human soul?
            I would imagine only real things could be replicated.
            To us, it is the BEAST.

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