Light into Matter.

Discussion in 'Physics & Math' started by Trippy, May 18, 2014.

  1. Trippy ALEA IACTA EST Staff Member

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    This shows theories describing light and matter interactions. Credit: Oliver Pike, Imperial College London

    Imperial College London physicists have discovered how to create matter from light - a feat thought impossible when the idea was first theorised 80 years ago.

    In just one day over several cups of coffee in a tiny office in Imperial's Blackett Physics Laboratory, three physicists worked out a relatively simple way to physically prove a theory first devised by scientists Breit and Wheeler in 1934.

    Breit and Wheeler suggested that it should be possible to turn light into matter by smashing together only two particles of light (photons), to create an electron and a positron – the simplest method of turning light into matter ever predicted. The calculation was found to be theoretically sound but Breit and Wheeler said that they never expected anybody to physically demonstrate their prediction. It has never been observed in the laboratory and past experiments to test it have required the addition of massive high-energy particles.

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  3. OnlyMe Valued Senior Member

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    Nice!

    And it will be interesting to see what happens next.

    I remain a skeptic, who would like to be proven wrong.
     
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  5. Farsight

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    Have a read of Opticks query 30 where Newton said "Are not gross bodies and light convertible into one another?" Matter is converted into light in something as simple as a fire. Not much of it, but some. What do you think pair production and annihilation is all about? And E=mc²? Or how about Two photon physics:

    "Two-photon physics, also called gamma–gamma physics, is a branch of particle physics that describes the interactions between two photons. If the energy at the center of mass system of the two photons is large enough, matter can be created..."

    NB: in the Wikipedia article you can also read that "From quantum electrodynamics it can be found that photons cannot couple directly to each other". That's wrong. Pair production does not occur because pair production occurred. Instead two photons interact. It's the inverse of say electron-positron annihilation.
     
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  7. RJBeery Natural Philosopher Valued Senior Member

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    This has been obvious to me since, well, forever. To believe otherwise would be granting a time-asymmetric process to Physics which simply seems wrong.
     
  8. Trippy ALEA IACTA EST Staff Member

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    All of the observed instances of pair production require the presence of a nucleus or a pre-existing electric field - a point that has been made to you countless times which you have ignored every time.

    The article in nature details how Breit & Wheeler's 1934 prediction can be confirmed, something which has yet to be done.
     
  9. RJBeery Natural Philosopher Valued Senior Member

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    The concept is theoretically, even aesthetically, sound. I have no problem with Farsight or anyone else referring to production of matter from light prior to observation in a lab.
     
  10. Trippy ALEA IACTA EST Staff Member

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    I think you've missed the point I was making.
     
  11. brucep Valued Senior Member

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    'That' prediction is a consequence of QED. Made in 1934 by Gregory Breit & John A. Wheeler. The amazing thing is developing the experimental technology to test the prediction. Experimental science is on a huge roll.
     
  12. Trippy ALEA IACTA EST Staff Member

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    I know, aint it great? Of course what would be even better (at least in my opinion) would be if the experiment failed - at least that might indicate which direction the next steps for physics should take.
     
  13. OnlyMe Valued Senior Member

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    In that case, I am optimistically skeptical.

    P.S. But wouldn't failure in this case be similar to the M&M failure, nothing more than a null result or a statement about the experimental mechanism? It wouldn't really prove photon interaction could not result in pair production.
     
  14. btr Registered Member

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    For what it's worth, I would say that Michelson and Morley's null result was pretty big news!

    Anyway, QED not only predicts that pair production is possible; it also predicts precisely how often it should happen under given conditions. According to the simulations (based on QED) run by Pike et al., their experimental set-up should be able to produce on the order of 10[sup]5[/sup] electron-positron pairs when they fire a burst of gamma rays into the hohlraum. If they do observe significantly fewer (or more!) than this, and their methodology stands up to scrutiny, and the result can be replicated, it would show that QED makes the wrong prediction about something which was previously thought to be well within its domain of applicability. That would be very big news indeed.
     
  15. brucep Valued Senior Member

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    QED. Great stuff. Thanks for the details.
     
  16. OnlyMe Valued Senior Member

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    My intent was that, you can fail to detect or accomplish an intended result, without proving more than that the experimental process was not up to the test.

    M&M did not prove that an ether does not exist. That is something that has become accepted, as a function of an accumulation of experience, experiment and theoretical development. All they proved is that they were unable to detect or measure, the existenace of such an ether. (Personally, the concept of an ether as it existed during that time in our history is not something I believe represents reality.)

    My original intent was only to point out that if the proposed experiment fails, it proves only that the experiement was unable to produce pair production directly from the interaction of two or more photons, not that such pair production does not occur.

    Though, as a matter of record I am rooting for failure, but would be just as happy with success.
     
  17. Kittamaru Ashes to ashes, dust to dust. Adieu, Sciforums. Valued Senior Member

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  18. Trippy ALEA IACTA EST Staff Member

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    I came across this image at RDFRS, they credit it to Nature Photonics:

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  19. Trippy ALEA IACTA EST Staff Member

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    Maybe, I suppose my statement comes with the implied caveat assuming that the experiment was set up properly.

    A failure may simply constrain the conditions under which it can occurs, but if it is supposed to occur under those conditions that too may hint at what lies beyond the standard model.
     
  20. Farsight

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    The big news is that light interacts with light.

    True enough. LIGO is an interferometer too. It hasn't detected gravitational waves, but that doesn't mean they don't exist.

    See arXiv re aether papers along with Einstein's Ether and the Theory of Relativity, and this:

    The experiment won't fail. We're here, aren't we? And like RJ said, physics is time-symmetric. Post saved in case Trippy deletes it and says I'm trolling.
     
  21. PhysBang Valued Senior Member

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    Yes, when considering serious science, one should always look to the alchemical comments that Newton added to the Opticks.
     
  22. btr Registered Member

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    To be honest I think the actual news here is that we've been able to overcome the considerable hurdles involved in testing this long-standing prediction. That is a tremendous achievement, regardless of the experiment's outcome.

    A little aside: this prediction was first made about 80 years ago! I wonder what the record for the longest-standing unconfirmed prediction of an widely-accepted theory is?
     
  23. origin Heading towards oblivion Valued Senior Member

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    Quit being a baby. If a physics question is asked in the physics forum then just answer with known physics and not your made up stuff then it won't get deleted.

    Back on topic, that is pretty cool how quickly they come up with that experiment. They also said the experiment was 'simple', uh, if they say so - it doesn't seem all that simple to me!
     

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