Physics + Math

03
Jul

Nearing Certainty About Heisenberg’s Uncertainty… Or Not

One of the basic tenets of quantum mechanics is Heisenberg’s uncertainty principle, which states that the more precisely one measures a particle’s momentum, the more uncertain its position becomes. The reverse is also true, which means that in theory, it’s impossible to know the exact position and momentum of a subatomic particle at the same time.

Heisenberg originally used the principle to show that there is a limit to the accuracy of particle detectors, but he never offered direct evidence to support his ideas. Now, UK physicist Paul Busch and his colleagues believe they have a proof. Here’s Ron Cowen, writing for Nature:

In their theoretical work, Busch and his colleagues imagined making simultaneous measurements of a particle’s position and momentum in an arbitrary quantum state. They compared the errors in such measurements to two special cases — in which either the position or the momentum of the particle is well known. They found that the combined errors in measurements of the position or momentum in these two cases obeyed Heisenberg’s principle and was always smaller than for cases in which the two properties were measured simultaneously. This step allowed them to prove Heisenberg’s original conjecture.

Scientists remain skeptical, though. Read the full article to learn more about one physicist’s objection to Busch’s proof, as well as what those doubts mean for quantum computing. For some background on quantum computing, hear from MIT’s Seth Lloyd. And for some comic relief, watch this video:

Quantum mechanics is nothing to laugh at. Well, sometimes it is.