Interpretation of Heisenberg’s Principle is Proven False

September 12, 2012



Students are taught that quantum uncertainty is always in the eye of the beholder, but that principle might have been proven false by a new experiment that measured a quantum system which doesn’t necessarily introduce uncertainty. It overthrows a common classroom explanation of quantum mechanics, but the fundamental limit of what is knowable at the smallest scales remains unchanged.

Scientists published their findings in the journal Physical Review Letters. The Heisenberg Uncertainty Principle states that there is a fundamental limit to what is knowable about a quantum system. The more precisely the observer knows a particle’s position, the less he or she can now about its momentum, and vice versa. The limit is usually expressed as a simple equation.


Heisenberg explains this principle by exposing how a scientist trying to take a photograph of an electron, has to bounce a light particle off its surface. This reveals its position, but imparts energy as well causing it to move.

Aephraim Steinberg of the University of Toronto in Canada and his team of researchers have performed measurements of photons and showed that the act of measuring can introduce less uncertainty that is required by Heisenberg’s principle.

The group didn’t measure position and momentum, but its polarization states. The polarization state along one plane is intrinsically linked to the polarization along the other. By Heisenberg’s principle, there’s a limit to the certainty to which both states can be simultaneously known.

The researchers compared weak measurements with strong measurements multiple times. They found that one measurement of one polarization did not always disturb the other state as much as the uncertainty principle predicted. In the strongest case, the induced fuzziness was little as half of what is predicted by the principle.

There’s still no way that you can know both quantum states accurately at the same time, states Steinberg. However, the experiment shows that the act of measurement doesn’t always cause the uncertainty.

[via Nature]

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9 Responses to “Interpretation of Heisenberg’s Principle is Proven False”

  1. StretcherBearer Says:

    So Are we Uncertain about the uncertainty? And what about the cat? Is it less dead and Less alive?


    • ClipAnApex Says:

      What you have to understand is Schrödinger’s cat was never meant as actual experiment, it was always a satirical thought experiment to show how uncertainty would manifest itself in a non-quantum system, and how little sense this interpretation really makes.
      Schrödinger would probably actually agree with this news.


  2. Roland Johnson Says:

    The cat died of old age, still in the box 50 years ago.

    Your Welcome


  3. Giovanni Imbalzano Says:

    An Heisenberg hypothesis not is satisfied anytime!


  4. Fernando Says:

    For some weird reason, I could never except the principle, it didn’t make any sense, and off course, at the time the answer was “its because you dont really understand the principle”, suffice to say, neither did they. I do wonder what implications this will have on quantum physics?


    • b.coats Says:

      Measurement still affects position, its derivative, and energy! This is only suggesting not as much as previously thought.

      The principle itself is still valid.


  5. Micha el X Says:

    It would be a pity if the principle of superposition lose its foundation.
    Always when my girl-friend try to reverse into a parking place i tell her the crash is not her fault because the physics tell that the place MUST blurry away when the impulse of the car is accurate.


  6. Madanagopal.V.C. Says:

    The product of error in observation of both position (x) and momentum (p) measured simultaneously is fixed by an equation of 1/2 of Planck`s constant or even more, in Heisenberg Uncertainty Principle. That means that if the error in position (x) is less , that is when measured accurately, the corresponding error in momentum (p) measurement increases correspondingly to keep the equation correct. In quantum states ( infinitesimally small states of matter) , classical accurate measurement will not work. This had been beautifully explained by light diffraction rings experiment when light is passed through two adjacent pinholes,where actual travel route of photons through the pinhole number 1 or 2 could not be ascertained. There is still no way that you can know accurately the two quantum states simultaneously, is agreed by the researcher Steinberg in the article. What he had ventured is to find a refined value of polarization states of light in different axis, to minimize errors. He has still not brought the product of (del X by del p) to zero and keeps close to the Heisenberg`s value of 1/2 of Planck`s constant value as far as possible. The inequality still holds good and cannot be thrown out by this article. Thank You.


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