A founding principle of physics gets a fresh look – and a revision.
– By Alex Hutchinson
German physicist Werner Heisenberg formulates the uncertainty principle: it’s impossible to measure the physical property of anything without disturbing what you’re measuring. For example, trying to measure a particle’s position changes its speed.
Japanese scientist Masanao Ozawa theorises that Heisenberg’s limit of uncertainty could be lower than previously believed. He claims that researchers can measure a particle’s properties without disturbing others, or at least disturbing them less than Heisenberg thought.
A team at the University of Toronto (shown above) uses a technique called weak measurement to delicately probe the properties of a single photon; the disturbance to the photon is less than the lowest uncertainty limit predicted by Heisenberg.
Why you should care?
For physicists developing quantum cryptography technology, the uncertainty principle is crucial. Information is encoded in photons that vibrate in a particular sequence, and only the sender and recipient have a key. If anyone else intercepts the communications, the photons’ spin will be affected, and the intrusion will be detected.