Transcript

MARCUS DU SAUTOY

I’m holding a pot of uranium. When will it spit out its next bit of radiation? Quantum physics posits that we can never know. Our third week reveals that at the small scale, unknowability might be an integral part of the way we must do science. At its heart is the tension between whether things like electrons or photons are best described as particles or waves.

It turns out that quantum physics puts inbuilt limitations on what we can know about the behaviour of the very small particles we met last week. Embodied in something called ‘Heisenberg’s Uncertainty Principle’, current theories of physics say that there’s no mechanism that will tell us when a pot of uranium is going to radiate, or where we’ll find an electron when you next look for it. Instead there seems to be a quantum dice deciding the future of the universe, whose dynamics will remain always hidden