Scientists Now Uncertain About Heisenberg's Uncertainty Principle

An experiment conducted at the University of Toronto has thrown a fundamental aspect of the Heisenberg uncertainty principle into doubt. For decades, we've believed that you can't measure a quantum state without inducing uncertainty — but now, we're not so sure about that.

While this new discovery doesn't overturn the uncertainty principle as a whole, it does indicate that certain aspects of Heisenberg's conjecture may need to be revised.

Heisenberg's uncertainty principle is an integral component of quantum physics. At the quantum scale, standard physics starts to fall apart, replaced by a fuzzy, nebulous set of phenomena. Among all the weirdness observed at this microscopic scale, Heisenberg famously observed that the position and momentum of a particle cannot be simultaneously measured, with any meaningful degree of precision. This led him to posit the uncertainty principle, the declaration that there's only so much we can know about a quantum system, namely a particle's momentum and position.

Scientists Now Uncertain About Heisenberg's Uncertainty Principle

Now, by definition, the uncertainty principle describes a two-pronged process. First, there's the precision of a measurement that needs to be considered, and second, the degree of uncertainty, or disturbance, that it must create. It's this second aspect that quantum physicists refer to as the "measurement-disturbance relationship," and it's an area that scientists have not sufficiently explored or proven.




But as noted, this quirk in quantum physics does not overturn the basic tenet of the uncertainty principle; we still cannot know a quantum system with precise certainty.

But that said, as Steinberg told Nature News, "[T]he experiment shows that the act of measurement isn't always what causes the uncertainty. If there's already a lot of uncertainty in the system, then there doesn't need to be any noise from the measurement at all."

You can check out the entire study at Physical Review Letters.

H/t to Geoff Brumfiel @ Nature. Image via shutterstock/optimarc. Inset image via.