Sunday, December 23, 2007

Why 'Common Sense' Quantum Physics?

Quantum Physics is generally presented as a weird, non intuitive field of Physics. The domain of application is however that of the simplest systems: discrete particles evolving in a carefully controlled environment. Such systems therefore obey the most fundamental laws of physics. And who says "fundamental" says: simple, intuitive, common sense, natural... My conviction is that quantum laws are the simplest way to express how nature behaves. Or said otherwise: quantum physics is intuitive, with respect to classical physics that is artificially constructed. In order to see this, we must however approach Quantum Physics in a perspective that remains unexplored. Rather than to try to link it to classical and relativistic physics, we ought to take a more direct way.

I love the way Feynman presents Quantum Physics. In his renowned public lecture QED: The Stange Theory of Light and Matter (1985), he says: You will have to brace yourselves for this - not because it is difficult to understand, but because it is absolutely ridiculous: All we do is draw little arrows on a piece of paper - that’s all! That's the essence of Quantum Physics: arrows. Mathematicians call arrows vectors, and there are very advanced, abstract ways to describe operations on such objects. But the mathematical artillery must not hide the fact that physically, we are handling with very simple objects: objects that are alike arrows, or rods, or needles, or ballpens, or baseball bats.

A child knows intuitively how such objects behave. Tintin's cartoon "Ottocar's scepter" shows a comic situation, in which the clue consists in correctly inferring how such an object could pass through a grid. In order to make sense of Quantum Physics, we'll have to brace ourselves for this: all we do is draw little arrows. So how could arrows help us to grasp the essence of Quantum Physics? The first thing is maybe to re-read Feynman's QED, or just visioning its 4 QED public lectures: Than just think about it.

There is not simpler a particle than a photon (apart maybe of a neutrino which is experimentally equivalent to a photon with zero frequency):
  • it has no inertia, its departing velocity with respect to the emitter is always the same (provided it does not find obstacles on its way),
  • it has a very simple polarization, when correctly oriented, it passes through a wire grid,
  • when constrained between two limits, its frequency may take only discrete values,
  • many photons with the same polarization may be beamed together,
  • in the quantum ocean of other quantum particles (essentially other photons or neutrinos), one photon creates and interacts with (we say interfers with) the wave it generates in that ocean (physicists speak of a field).

Such a particle may be represented by a rotating arrow whose rotational plane has a constant orientation between two obstacles.

This common sense way of interpreting Quantum Mechanics is explored at Wikiversity/Making_Sense_of_Quantum_Mechanics.


  1. Hi,
    I'm a very amateur philosopher
    who is currently working on a book
    along these same ideas.Would like
    to stay in touch for assistance
    with some of my questions from a trained scientist like yourself.

    These are ideas I've had since
    the 4th grade.Iam now 56 years
    old and all my ideas have come together.

    If you feel that I do not belong
    in your group please let me know.

    Thanks, Percy Sears

    My google blog is foundationsfor solvingtoe ,good luck in your quest for the "holy grail"

  2. Hello Percy,

    Fine to hear from you. I am curious about your ideas and your book. It would be a pleasure for me to converse about it. Please keep me informed.

    Kind regards,

  3. Are you planning to use QM as the main argument in these areas of your physics for the theory of everything?

  4. Hi Arjen

    Yes, I totally agree with you that QM is an easy and intuitive way to see the world but when it comes to the stranger things of it then I am doubtfull, like the EPR paradox, entanglement and stuff like that.

    But else I am really impressed by QM.

    Cheers and good luck with this blog, will have a look regurlarly.

  5. Hello Brett,
    The field of application of QM ranges from very simple systems (one photon, one electron...) to composite systems. Gravitation applies for systems with a huge amount of particles. That's why I think that a Theory of Everything must be based on QM. Gravitation will unfold deductively for a huge number of elementary particles.

    Hello Olafur,
    Thanks for the cheers and good luck with your master thesis.