back to article SQUID calls 'virtual photons' into real existence

While “vacuum fluctuations” – one of the stranger predictions of quantum physics – have been observed for some time, a team comprising scientists from Chalmers University of Technology in Sweden and the University of University of New South Wales have gone one step further, creating their own photons out of empty space. Here’s …


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  1. Anonymous Coward
    Anonymous Coward

    Wow. Brilliant work.

    Now watch all the folks who were running time-travel pieces on the back of the OPERA results run pieces proclaiming the arrival of free energy...

  2. Geoff May

    Does this mean we can now let Schrödinger’s Cat out of the box?

    Poor thing must be busting for the litter tray ...

    1. Michael H.F. Wilkinson Silver badge

      Schrödinger’s Cat has tunneled away years ago

      Any cat can always appear at the other side of a closed door, even when you just observed it on THIS side.

      1. hplasm

        As Eddie Izzard observed-

        "That's not purring- it's drilling..."

    2. Chemist

      "Poor thing must be busting for the litter tray"

      It might be or maybe not - you'll have to look

      1. BorkedAgain


        Don't you mean "It is and it isn't..." ;)

        Mine's the one that may be a mac or possibly a sports jacket, depending on the weather observed outside.

    3. Pooua

      Ironically, I had a dream last night that I was trying to revive a half-dead kitten in a cage.

  3. Rich 2 Silver badge

    Dark matter?

    Is there any connection between this virtual "stuff" and "dark matter" then? Seems, on the surface at least, for the former to be a candidate for explaining the latter. But then again, I know sod-all about what I'm talking about. Anyone out there that DOES know?

    1. Destroy All Monsters Silver badge

      Not really.

      Virtual particles are just that - virtual - so you can't observe them, even on the mass detector though they do transmit forces like the electrostatic force. (Well, theoretically the VPs should generate a massive "vacuum energy" of zillion Joule per cubic centimeter but this is clearly not observed).

      To observe them, you have to kick them loose. This is not unlike using a hammer to break a fat piece of concrete out of a smooth wall. The wall is just the whole set of possible concrete pieces, but you dont' get see the pieces. To see a piece you have to impart serious energy. Indeed, this is what happens in colliders when high-energy photons suddenly transform into particle-antiparticle pairs.

      Seems to be the same here. The mirror imparts energy, particles are coming out, the mirror's kinetic energy goes down, it balances out.

      1. Robert E A Harvey

        'clearly not observed'


        Rather like the various 'virtual' returns of Christ in the last century?

    2. Is it me?

      They learn

      The quantum tunnelling tool used by cats to move through doors has been known to science for many years.

      It's called a human being, cats learnt that if they sit by a door a human will come along and open it, let them through and then close it, usually without remembering the action, thus proving that cats are capable of mind wiping humans.

      More advanced cats have also developed their humans to provide a more sophisticated device that allows the cat to move through doors without human intervention, and further to do so only for themselves. This device is known to be manufactured, secretly, by Staywell, in some quantity.

      Roumour has it that some smaller breads of dog have belatedly caught on.

  4. Dodgy Geezer Silver badge
    Thumb Up

    Well Done!

    "... I realize I didn’t win any science-scoops competition with this story. I’d rather understand what’s going on and explain it than be the first to run with the press release...."

    And for that I congratulate you.

    A huge problem with all media at the moment is that frenetic dancing and exclamation marks seem to stand in for understanding. We are dumbing down our population at a rapid rate. If all comentators (particularly political and economic) were to have deep understanding and explain what they say, instead of concentrating on rumours of sexual pecadillos, the world would be a much better place....

  5. Anonymous Coward
    Thumb Up

    "I realize I didn’t win any science-scoops competition with this story. I’d rather understand what’s going on and explain it than be the first to run with the press release."

    More of this please!

  6. Bassey

    Fan-bloody-tastic. Thank you

  7. I ain't Spartacus Gold badge

    Please stop it

    Please stop reporting on quantum theory, it's making my head hurt.

    Isn't there some nice science involving fluffy kittens you could be reporting on? And I don't mean locking them in a box with a radioactive source and some poison either. That's not science, just student pranks...

    Proper science would be designing a death-ray to kill kittens in their millions. Or at least thousands...

    Keep up the good work!

    1. BlinkenLights

      Kitten Death Ray

      The kitten death ray sounds like a good project for the RSPB to fund. Stop them growing up to be garden bird killers.

  8. stucs201

    Implications for interstellar space-ships?

    Does this mean it might be better to make interstellar spaceships according to the Disaster Area school of design (*black*), rather than the Naboo school of design (Coversed in shiney mirrored chrome)?

  9. Christoph

    Relative to what?

    "if one could accelerate a mirror very quickly to near the speed of light, the mirror would radiate light"

    Relativity says there is no absolute frame of reference for motion, no fixed frame to measure speed, only motion relative to other things.

    So what is this "near the speed of light" relative to? It can't be speed relative to the vacuum, that would establish a fixed frame.

    Physics should be the same to all observers, whatever their velocity. So I don't see how they are working this, something must be missing in the description.

    1. relpy


      Not quite.

      You're right about there being no fixed frame of reference, but relativity also says that the speed of light is the same in *all* frames of reference. In fact that's one of the assumptions upon which special relativity is based.

      Don't think too hard about that by the way, certainly don't think too hard about the level of genius required to take that as a starting point. If you must - here's a hint - time isn't a constant, and speed is distance travelled per unit time.

      Beer - you may need one :-)

      1. Christoph

        Yes it's the same

        "the speed of light is the same in *all* frames of reference" - yes, that's exactly the point.

        From the mirror's point of view, the speed it measures light at is the same, so in its own frame of reference it is *not* travelling near the speed of light.

        So there's no reason at all for those virtual photons to act any differently than for a mirror "at rest" - the mirror thinks it is itself at rest.

        1. relpy

          Okay, see where you're coming from.

          Mind, the mirror is accelerating and is therefore in a non-inertial reference frame, so it's all going to be a bit cock-eyed anyway. And the mirror is well aware of that.

        2. Destroy All Monsters Silver badge


          See also:

        3. Justicesays

          The key is


          Being accelerated is specific to your frame of reference, which is why this involves a mirror being accelerated to 25% of light speed, not just one coasting along at that "speed". The light emission only happens during the (brief) acceleration period.

          This is also why in the "twin paradox" of special relativity, its the twin who travels far away at near light speed and comes back that is the younger one, even though from eithers frame of reference you could say that its their twin thats is moving at near light speed. Only the travelling twin experiences the acceleration.

    2. Blue eyed boy

      Relative to the observer of course

      This sounds like Unruh radiation, which arises because the mirror is accelerating. (It is "not at rest" though that is nothing to do with the name of the resultant radiation.) AIUI if a virtual photon just happens to appear immediately in front of the mirror, it strikes the mirror and is reflected before it can disappear up its own. Because the mirror is accelerating, the photon is given enough extra oomph that it is no longer virtual so in fact never does vanish up its own but goes off into space as an ordinary photon.

  10. ~mico


    So, imagine you have this peace of mirror being fired at half-lightspeed from this starship... It slows down by this sort of emissions, while starship gets a small momentum... then slowly pulls the mirror back, loosing *less* of that momentum. Conservation of momentum, you say?

    1. Richard Scratcher

      Not hyperdrive but maybe a Photonic Laser Thruster (PLT)

      This may explain why UFOs are shiny spinning things.

  11. Anonymous Coward
    Anonymous Coward


    Has this got anything to do with Tesla and his zero-point energy from a vacuum?

  12. ian 22

    "not just a theory"

    Have the Creationist's "evolution is just a theory" reality distortion field enveloped this author?

    Theory is based on observation, and constitutes the best explanation or the observed phenomena. The author

  13. Chris Hennick

    Conservation laws?

    So does the photon ever disappear back into the Dirac sea, or do we need to rewrite conservation of mass-energy--curvature--whatever-else?

    1. Frumious Bandersnatch

      as I understood it

      No, the photon doesn't have any expiry date on it just because it came from the soup(*). Also, energy is conserved because the mirror's momentum is sapped by an amount equal to and opposite of the energy of the created photon. Or, since the mirror isn't physical in this case, the creation of photons means that the power supply for the apparatus has to pump more joules in in order to achieve the same acceleration curve.

      (* Although I'm sure the Thomas Edison Electric Light Company (aka General Electric) would love to be able to sell photons with a "use-by" date, a quick search shows that photons are thought to have an infinite half-life)

    2. Anonymous Coward
      Anonymous Coward

      Energy is used

      to accelerate the mirror. I don't know the math, but I betcha you can't get more energy out of it in terms of photons, than you put into it in terms of oscillating the magnetic field.

    3. Thomas Allen

      Conservation laws are already gone

      Conservation laws are already gone - See Hawking radiation - quantum uncertainty creates particle pairs, one disappears down the black hole while the other does not - matter is being "created" from the vacuum. Something from nothing. With enough time, whole universes could be built.

      Now if we could just extract Casimir particles of choice, say, carbon atoms, we could be creating oil for our cars. Maybe build our own Star Trek replicators.

      1. Chemist

        "Conservation laws are already gone #"

        NONESENSE !

        Particles created near black holes are effectively taking mass from the black hole which will eventually vanish ( if no matter replenishes the black hole ) This is exactly why micro black holes are thought to have a very short lifetime and hence if the LHC somehow managed to create any it wouldn't be a problem

  14. Phil Riley

    I too applaud you for this

    "I realize I didn’t win any science-scoops competition with this story. I’d rather understand what’s going on and explain it than be the first to run with the press release."

    You have written an erudite article, that helps explain a very weird phenomenon. Thank you for taking the time to understand and explain it.

    From a fellow physics graduate working in the IT sector.

  15. Stevie


    Gotta love Physicists. "Near" = "25%"

    Now try this one: "You're nicked sunshine. 100 mph in a 30 mph limit!"

    "I was doing 25!"

    "That's near enough. It's the high jump for you, me lad. You'll do time for this".

    1. Tom 13

      It's not the physicists' fault.

      At 25% the effects in the equations become detectable at a reasonable cost (relative to other quantum and relativistic experiments). Even 5% lower than that and it can't be done at a reasonable cost. If you attempt to boost the relative speed higher, the cost of the equipment to move the mirror becomes unreasonable, even though the cost for the detection would go down.

      1. Stevie


        Got that. Questioning the claim that 25% of anything can be classed as "near" that thing.

        Not calling the physics into question, merely the write-up.

  16. Is it me?

    Hold on, some questions

    If an object is travelling away from it's origin at 2/3 light speed, and another is travelling in the opposite direction at 2/3 light speed. Would not an observer on one of those objects observe a greater than light speed event relative to their position?

    As to creating energy from the magnetic field ocellation, well wouldn't that depend on how much energy was required to ocsillate the magnets compared to that produced?

    1. disappointed

      Time dilation effect

      Time passes at different speeds (stating it simplistically) for the traveller and the origin (slower for the traveller). Hence, for the traveller, the other traveller going in the other direction is not moving at superluminal speeds.

    2. Christoph

      Re questions

      No. The speeds don't add up like that. This is the heart of special relativity.

      Speed is distance travelled per time. Both distance and time change when you travel near light speed. When you allow for this, the total speed always comes out less than light speed.

      This sounds weird, but it is not fiddling the figures - it's the way the universe works.

      It really does happen. The big particle accelerators have to allow for these effects, and they see exactly this happening just as the theory predicts.

    3. Stevie


      Always go to the source.

      Read. Think about what you've read for a bit. Get less downvoted in physics topics by anonymous cowards.

  17. Woenk
    Thumb Up

    It may not have all the details in it, but those would most not understand anyway and since real world applications are probably a century away, the reading gave me a slight woozy feeling that we still discover "what the hell is going on" bit by bit. Nice to read, thank you.

    I wonder...did they just check the light emittance ? With those relatively high magnetic fields, the motion and energy in a small spot, they might have even produced a few gravito-photons, could maybe give some indications concerning Heim's theories and if they are anything near real.

  18. bahamut

    This means

    that the effect described here, can be used to produce connected photon-pairs for quantum-state teleportation?

    "the observed photons have properties predicted by quantum theory"

    this sentence is very important, if it means what i'm thinking of. Does this mean that we know the quantum state of the created photons? Because the main problem of quantum-state teleportation was, that we don't know the initial state.

  19. Pooua

    A New ''Connections''

    I'm old enough to remember a show called, "Connections," about the path of discovery and invention that led to our modern technology. This new discovery might be another step in that path.

    Several years ago, I read about a proposed spacecraft engine based on this same principle. You may recall that light imparts momentum to an object when the light reflects off it. If you could bounce a laser beam off an object in space, you could impart acceleration on the object, or, if you could shoot light or lasers from an object in space, you could use them for (very weak) thrust of the object. Over a long period of time, the acceleration would build up, but no power supply would last long enough for it to make a difference. This new engine, though, uses Casimir plates on springs to form terahertz oscillators, generating light, and from that, propulsion. The power supply problem would be eliminated, because the device is powered by quantum fluctuations from the quantum vacuum. Now that scientists have made the equivalent in a lab, though undoubtedly with a conventional power supply to the oscillating circuit, perhaps we are that much closer to making the Casimir spacecraft engine.

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  21. Anonymous Coward
    Anonymous Coward

    The physics'll keep.

    Not only getting it right (well, I don't have the background to check; let a quantum physicist proofread?) but explaining it in such a way that lay people understand it and get the gist correctly isn't exactly easy. Something too few in any technical business understand nevermind can do themselves. I think we can stand a bit of delay on the science scoops for that reason.

  22. Luc Le Blanc

    Mirror or magnet ?

    At end of 4th paragraph, in "and the effect is the same as a magnet moving at 25 percent the speed of light.", shouldn't "magnet" be replaced by "mirror" ?

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