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A Very Convincing Quantum Experiment?

  1. Jan 15, 2010 #1
    Hi all, this is a post from an absolute NITWIT in physics.

    I am looking for very convincing multiple times verified experiments for laymans which demonstrate quantum effects on photons.

    I looked at the double split experiment, found it unconvincing. What's all the fuss if you assume photons are neither particle nor wave, but something else.

    I looked at EPR, found it unconvincing, I don't see any real reason to assume that entanglement is anything else than some observation on something 'a photon' which is just more complex than we understand. (I am referring to Joy Christian also). And found it even more unconvincing that no information can be transmitted, if entanglement is only statistical correspondence, I just don't see any real effect.

    I looked at an experiment done by Dopfer, which is _very_ convincing. A beam is split, the particle up is forced into one of two states (particle/wave) by a Heisenberg device on one route, an interference pattern or two bands are observed on another route.

    Unfortunately, I convinced myself that you would be able to build a phone into the future from that. And found out some people are even doing that, so I couldn't convince myself there was no fluke in her particular setup.

    Is there an experiment which shows a quantum effect so blindingly obvious to a layman that he has no choice in accepting that quantum effects occur? Preferably a similar setup like Dopfers, where it seems information need to travel to an entangled photon backward in time?

    I do not doubt QT, and certainly not its usefulness. I am just a very sceptic person, and cannot convince myself that QT is just a theory which works well, but QT effects, particularly when it comes to observance, are grossly overestimated.

    Thanks all.

    [Another confirmation of the effect of Dopfer would also do it of course.]
    Last edited by a moderator: Jan 15, 2010
  2. jcsd
  3. Jan 15, 2010 #2


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    Welcome to PhysiscForums, MarcoD!

    You kind of pick and choose which ones convince you and which ones don't. That is your right, but it does not make for good science. First, I would ask, what do YOU think light is if it is NOT a quantum particle? That might be a good starting point for you to compare to what others believe.

    Quantum theory is a mathematical formalism, and is notoriously complex in some areas. Other areas are easier, and are often provided to the layman to get past the problem of complexity. However, if you are willing to examine the logic of the following paper in detail, you will find a most convincing proof of the quantum nature of light. But this is not for the timid!

    Observing the quantum behavior of light in an undergraduate laboratory

    "While the classical, wavelike behavior of light interference and diffraction has been easily observed in undergraduate laboratories for many years, explicit observation of the quantum nature of light - i.e., photons - is much more difficult. For example, while well-known phenomena such as the photoelectric effect and Compton scattering strongly suggest the existence of photons, they are not definitive proof of their existence. Here we present an experiment, suitable for an undergraduate laboratory, that unequivocally demonstrates the quantum nature of light. Spontaneously downconverted light is incident on a beamsplitter and the outputs are monitored with single-photon counting detectors. We observe a near absence of coincidence counts between the two detectors—a result inconsistent with a classical wave model of light, but consistent with a quantum description in which individual photons are incident on the beamsplitter. More explicitly, we measured the degree of second-order coherence between the outputs to be g(2)(0)=0.0177+/-0.0026, which violates the classical inequality g(2)(0)>1 by 377 standard deviations."
  4. Jan 15, 2010 #3
    You kind of pick and choose which ones convince you and which ones don't. That is your right, but it does not make for good science. First, I would ask, what do YOU think light is if it is NOT a quantum particle? That might be a good starting point for you to compare to what others believe.

    You gave me an excellent answer, i thought of (something close to) 'ripples' -its the only thing which solves the double slit experiment,- but wouldn't dare propose it to a physicist. So I am very glad I was confirmed on a hunch, great yes, excellent answer.

    It seems I confused Quantum Mechanics with Quantum Fields, both of which I have little knowledge except for having seen some diagram once.

    I guess I may assume that given Quantum Fields, there is a perfect, if still unsound, theoretical framework which puts everyone square into a relativistic world, and given that, there is no real need to see too much into quantum effects such as non-locality, observability and entanglement? [Forget it, found the answer. You need QM - but, not convinced...]


    Good, I have a tendency to edit posts. Thanks for the article, it gives a great insight into the current understanding of what a photon is according to quantum theory. The reason I am not convinced is that even if it exposes the dual nature of a photon, and the interplay of QF and QM, it doesn't imply that duality cannot be described with a unified relativistic description. For example, a piece of mercury on a tabletop can be pushed through two holes, bounce of objects, fibrate, and under correct circumstances end up as a whole on either side of the table.

    The experiment exposes quantum theory, I was hoping for an experiment which shows something really unexpected. But, thank you for your time and your answer. I give in, I cannot hope to understand this in a few days.
    Last edited by a moderator: Jan 15, 2010
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