Question: Do you know of any theories of anything smaller than a planc?

David Pyle answered on 14 Mar 2011:

Gosh – this is a way outside my expertise!

The Planck scale is a really tiny scale – it’s a length of about 1.6e-35 m (where the ‘e-35’ notation means ‘times 10 to the power of -35); and a timescale of about 5e-44 seconds. On the other hand, it is an enormous energy (1.2e31 electronVolts). At these extraordinary scales, the idea is that existing theory must start to break down. Well, I don’t know of any alternative theories – but as I say, it is a long way from my expertise.

But how would we ever make the measurements we might need to test the new theory? The Planck length is a sextillion (1e21.. a billion trillion) times smaller than an atomic nucleus; the Planck energy is a billion billion times larger than anything we can achieve in the most energetic particle colliders on Earth.. And if we can’t make observations to test the theory, then are we still in the field of science? Or have we moved into the realm of what people might call natural philosophy?