Heisenberg’s uncertainty principle not so certain anymore?

Heisenberg’s uncertainty principle is a cornerstone of modern-day physics. Formulated by the German physicist Werner Heisenberg, the principle suggests that at the quantum level, one of the most fundamental levels in the physical world, an observer can never know the exact position and speed of a particle, and by observing the particle, knowing its possible speed at a certain position, they affect the event.

While quite paradoxical sounding, the uncertainty principle has been ingrained in quantum mechanics and also seeped into philosophy. And very much like the laws of motion or relativity, the principle has been a fait accompli, never being challenged.

However a new research conducted by the University of Toronto has gone a step further than challenging the principle, and has actually stated that the principle may not actually be sound.

Published in the journal Physical Review Letters, the research has it that at a certain level, Heisenberg’s uncertainty principle does not hold true and that it was possible to know both a particle speed and position at the same time. Under the principle, when an observer tries to determine a particle’s position, this in turn “blurs out” the precision with which they could measure the particle’s speed. But the present research shows that this is not the case and that the problem of simultaneous measurement is not just restricted to particles, as the lead researcher Professor Aephraim Steinberg, explains:

“You find a similar thing with all sorts of waves. A more familiar example is sound: if you've listened to short clips of audio recordings you realise if they get too short you can't figure out what sound someone is making, say between a 'p' and a 'b'. If I really wanted to say as precisely as possible, 'when did you make that sound?', I wouldn't also be able to ask what sound it was, I'd need to listen to the whole recording. … Heisenberg had this intuition about the way things ought to be, but he never really proved anything very strict about the value. Later on, people came up with the mathematical proof of the exact value."

In the present study, researchers conducted an experiment in which they were to take so-called weak measurements of a pair of photons. In the experiment the researchers found that while obtaining their weak measurements, observation of one physical property did not “blur out” the other. As the researchers explained, "The quantum world is still full of uncertainty, but at least our attempts to look at it don't have to add as much uncertainty as we used to think!"

Of the implications of this research, the authors said that while no perceptible real-world changes would be seen, further research was indeed needed. There would certainly be a change to quantum cryptography and those technologies that depended on the uncertainty principle.