back to article Is light a wave or a particle? Beaming boffins prove it's BOTH

The old conundrum is right: not only is light both a wave and a particle, but Swiss boffins have captured it behaving as both at the same time. And this is what it looks like (click for the bigger version): EPFL wave and particle image Upper image - light as wave Lower image - light as quanta Image: EPFL The researchers …

  1. Douchus McBagg

    awesome!

    Wow mind blown! Learnt lots from this article! More please :D

    Had no idea about the photonic interaction with metalics. Plus lasers!

    Plus happy my brain is working at ten to six in the am.

  2. Mage Silver badge
    Boffin

    surface plasmon polaritons

    Heavy Boffinry!

    I've never heard of "polaritons" before. The plasmon, barely.

    (laser safety goggles on)

  3. Alister

    But... but... did they reverse the polarity of the neutron polariton flow?

    1. Doogs

      Should that be "reverse the neutrality of the polariton flow"?

  4. Zog_but_not_the_first
    Thumb Up

    Brilliant!

    Ya canna change the laws of physics.

    1. Tom 7

      Re: Brilliant!

      Staring very hard at things really does affect them!

      1. Paul Crawford Silver badge

        Re: Brilliant!

        Except goats. They just don't care.

        1. Anonymous Coward
          Anonymous Coward

          Re: Brilliant!

          Until you come to labelling them wrongly.

          1. Alister

            Re: Brilliant!

            I have never, knowingly, mislabeled a goat.

  5. Andy The Hat Silver badge

    Some electrons, a laser and a wire and you get a wobbly thing.

    Exactly as I predicted in my treatise "On the reaction of a wire-restrained aardvark when irritated with a frikkin' shark-controlled laser pointer."

    1. Elmer Phud

      "On the reaction of a wire-restrained aardvark when irritated with a frikkin' shark-controlled laser pointer."

      Erm, you do know that Apple are after $200mil for you using that quote?

  6. Stella Duvel

    But...

    Everyone has known for years that light is made of string wavicles...but it's nice to have pictures

  7. PlinyTheElder

    So... the EPFL article says Photograph, surely it's more of an Electrograph if it's imaged using Electrons as apposed to Photons? Amazing to see proof of the duality!

  8. Mike Bell

    Either... Or...

    Actually, the double-slit experiment, which has been around for a very long time, demonstrates quite convincingly that light exhibits both particle and wave-like properties simultaneously.

    The interference pattern in this experiment clearly shows wave-like behaviour. But one may also reduce the intensity of light so that the pattern builds up over time, photon by photon, with the resultant impacts being very particle-like.

    One way of looking at this is that the photon 'knows' that there are two slits available and - somehow - passes through both simultaneously, interfering with itself to produce a statistical pattern.

    Then we're back to the old conundrum of finding out why a particular photon ended up in a particular place (no pun intended). Which is made all the more fascinating that, in Many Worlds, multitudes of possible outcomes actually took place.

    1. Paul Kinsler

      Re: Either... Or...

      Since light is massless, it can never be localised in the way (eg) an electron can. Consequently, it is never "particle-like" in the sense most people would mean. Light is (IMO) better described as a "countable wave" ... although you are allowed to count the photons (light excitations) in really quite exotic ways - hence light can not only be in (ordinarily countable) number states, but also coherent states, squeezed states, or might be bunched or antibunched ... or be in any kind of superposition or mixture or those.

    2. Martin

      Re: Either... Or...

      Actually, the double-slit experiment, which has been around for a very long time, demonstrates quite convincingly that light exhibits both particle and wave-like properties simultaneously.

      Why? I can see that it clearly demonstrates that light exhibits wave-like properties. You can do a very similar experiment with a ripple tank and show the distinctive interference pattern of waves through a double-slit - and you can duplicate those interference patterns with light, very simply.

      But how does the double-slit experiment demonstrate that light behaves like particles?

      1. JeffyPoooh
        Pint

        Re: Either... Or...

        Martin asked: "But how does the double-slit experiment demonstrate that light behaves like particles?"

        You close one of the slits.

      2. Paul Kinsler

        Re: how does the double-slit experiment demonstrate that light behaves like particles?

        If you turn down the light intensity so that the rate of photons passing through is manageable, you can take a movie of the screen where the interference pattern will be seen. Each new photon that arrives makes a dot, and only after very many dots (photons) are registered do you see the interference fringes appear with their nice intensity gradients from dark to light. Those "dots", are often regarded as evidence of the particle-like nature of light (although strictly they only demonstrate the "countable" or energy-packet nature of photons, and the localization of whatever the dtos are - whether ccd or photosensitive molecule.)

    3. NumptyScrub

      Re: Either... Or...

      The interference pattern in this experiment clearly shows wave-like behaviour. But one may also reduce the intensity of light so that the pattern builds up over time, photon by photon, with the resultant impacts being very particle-like.

      I thought that one was usually done with electrons, which convincingly shows that "particles" can (and do) exhibit wave-like properties just like de Broglie postulated. The much weirder part is checking for complementarity by trying to measure which slit the particle actually went through, and (partially or completely) destroying the interference pattern in the process.

      Or in other words, if you make sure you keep a close eye on particles then they stop waving and interfering with each other, which could probably be labelled as Quantum Surveillance-state Dynamics (QSD). ^^;

      I'm failing to see how this experiment breaks complementarity though, as I don't think there is a direct measurement of a photons particle properties (position or velocity) while it is a constituent of a standing wave, it is all inferred from the energy exchange between photon and electron being quantised. Is there something obvious I'm just too dumb to see?

  9. Graham Marsden
    Thumb Up

    I stil don't really understand it...

    ... but I loved the cartoon explanation!

  10. Rich 11

    All perfectly clear/unclear now

    I both understood it and didn't understand it. I assume that at some point I will collapse.

    1. Toltec

      Re: All perfectly clear/unclear now

      If a photon within its own frame of reference experiences no time and therefore all points in the universe are the same point then are all photons the same photon?

  11. Steve Graham

    Wrong

    Photons (and electrons) aren't "both" waves and partcles. They're something in the quantum realm that we can imagine being a bit like waves and/or particles in the macroscopic world.

    When people ask what is "really" happening, they actually want an explanation that they can understand in terms of billiard balls or cabbages, and there isn't one.

    1. Martin

      Re: Wrong

      ...that we can imagine being a bit like waves and/or particles in the macroscopic world.

      It's a bit more than that. We can demonstrate that, under certain circumstances, they are behaving exactly the same as waves do, and we can demonstrate that, under other circumstances, they behave exactly the same way as particles do. It's nothing to do with imagination - we can clearly see the results.

      But I agree, asking what "really" happens doesn't make much sense.

  12. Anonymous Coward
    Trollface

    Pictures please or it didn't....oh. Forget that.

  13. ukgnome

    woah

    I have no idea what this could mean for humanity, but I do rather like it.

  14. earl grey
    Joke

    CUDOS

    A bad movie about a bad dog...

  15. Stevie

    Bah!

    "Professor Ben Eggleton of Sydney University's CUDOS research group explained that photons can be guided along a metallic wire in the form of plasmons (surface plasmon polaritons)."

    I'm glad we cleared that up.

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