University of Toronto scientists cast doubt on renowned uncertainty principle

Oh, my. That would be interesting indeed.

Werner Heisenberg’s uncertainty principle, formulated by the theoretical physicist in 1927, is one of the cornerstones of quantum mechanics. In its most familiar form, it says that it is impossible to measure anything without disturbing it. For instance, any attempt to measure a particle’s position must randomly change its speed.

However, this isn’t the Uncertainty Principle, it’s the observer effect. To be fair, this was the original argument that Heisenberg put forth back in the early days of QM, but not what it became: that you cannot simultaneously determine the position and momentum. It’s problematic that the observer effect description is still taught when introducing the HUP (much like the problems introduced by teaching the Bohr model).

The APS summary does a much better job.

When first taking quantum mechanics courses, students learn about Heisenberg’s uncertainty principle, which is often presented as a statement about the intrinsic uncertainty that a quantum system must possess. Yet Heisenberg originally formulated his principle in terms of the “observer effect”: a relationship between the precision of a measurement and the disturbance it creates, as when a photon measures an electron’s position. Although the former version is rigorously proven, the latter is less general and—as recently shown—mathematically incorrect. In a paper in Physical Review Letters, Lee Rozema and colleagues at the University of Toronto, Canada, experimentally demonstrate that a measurement can in fact violate Heisenberg’s original precision-disturbance relationship.