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Uncategorized Friday, September 7th 2012 at 4:47 pm

Researchers Uncertain of Heisenberg Uncertainty Principle

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The Heisenberg Uncertainty Principle is one of the most well-known and dearly held tenets of modern quantum physics. It’s one of those things about science you totally know, even if you don’t know you know it. The principle states that on a quantum level, you can’t directly measure anything without changing something about it. Thus, it is impossible to measure a particle’s position without affecting its velocity, and vice versa. Still confused? Us to, but luckily this Futurama clip explains the matter brilliantly in the first 30 seconds or so. Go ahead, we’ll wait. Back? Great. Now that you understand the uncertainty principle, it’s time for the news about it. Thanks to new measurement techniques, physicists are no longer certain that the theory holds up.

Researchers at the University of Toronto may have overcome this obstacle to finely measure quantum particles with a new technique known as “weak measurement.” In using a weak measurement, the device on which the particle is being measured is nearly imperceptible. After a first weak measurement, researchers sent the particle into a device that measured its velocity, and then measured its mass again using the weak measurement, giving them a good look at how much the act of measuring actually disturbed the particle. Knowing how much the particle is disturbed means it can be functionally weighed by disregarding the amount of disturbance, which is known, and makes the Uncertainty Principle less than certain.

“Each shot only gave us a tiny bit of information about the disturbance, but by repeating the experiment many times we were able to get a very good idea about how much the photon was disturbed,” said Lee Rozema, lead author on the study that was published this week in the journal Physical Review Letters.

It’s not yet a perfect technique, but it suggests that there is a way to work around one of the most generally agreed upon matters in physics. Now if we could only find a similar workaround for stupid gravity, because man, am I tired of waiting around for jet packs.

(via Science Daily)

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  • anonymous

    Star Trek (various series franchises) had this in the Heisenberg Compensator featured in several episodes. Is matter transport, replicators, etc, impossible or really next?

  • anonymous

    This summary is complete garbage. The Toronto researchers’ work is *not* challenging the Heisenberg uncertainty principle. The HUP rigorously follows from the basic postulates of quantum mechanics and, unless QM is radically rewritten at a very fundamental level, is unassailable. What they’ve done is confirmed experimentally that a common (mis) application of the uncertainty principle is, in fact, wrong. The uncertainty in the uncertainty principle is an intrinsic property of quantum states. Where it gets abused, however, is in applying it to individual measurements of the quantum system. Unfortunately, Heisenberg himself made this error at first which has contributed to much of the confusion. When a measurement is performed, it tends to disturb the thing being measured somewhat. This is an informal, non-rigorous idea and is properly called the “observer effect”. In the past, people have tended to confuse the observer effect with the HUP and used the Heisenberg uncertainty relation to say what an ideal measurement would look like. This is wrong, and it was proved to be wrong about 10 years ago. There *is* an inequality that the uncertainties in a measurement obey, and its different the from the HUP. The Toronto researchers have now performed an experiment that shows applying the HUP to measurements is wrong. The uncertainty principle is *not* uncertain, we just have direct experimental confirmation of what we learned a decade ago—that it can’t be applied to individual measurements.