The St. Pauli Girl Exclusion Principle



Some Photons Yesterday

That nice Brian Cox knows how to give the brain a work out. I read the Chapter on why atoms have solidity despite being mostly empty space. I was alright with the energy levels at the beginning but I got lost in the middle with the explanation of fermion spin and why it leads to the Pauli Exclusion principle. I'm quite happy to accept that this means that no two atoms can occupy the same Quantum State which means they give the atom dimension and consequently this results in volume and the fact that no two pieces of matter may occupy the same space. Which is why we don't fall through the floor.

However, I'm not sure whether this is the result of electrical repulsion between electrons and protons or whether it is something that is an inevitable result of pure mathematics. This almost suggests that the entire universe is sneezed into existence just because 1 = 1 and all the subsequent proofs. I am sure that is not correct. But knowing that common sense has to be suspended for a lot of this, maybe it is. I'm afraid we just have to take their word for it - which is a bit like faith really isn't it. Let's not go there.

Which End of Him is Thick Then?

BBC4 are going for a week of map-related stuff pivoting on the four-part Beauty of Maps (narrated incidentally by the steely-voiced, Scottish X-Wing Pilot and Uncle of Obi-Wan - Denis Lawson). Last night this was about the Mappa Mundi which despite being in Hereford and close to where I grew up, I have never seen. This is a map which would probably keep me happy for hours (once I'd learnt to read Latin I suppose) though Grayson Perry's tribute/homage to MM, Map of Nowhere is a modern substitute. Give me an atlas an I am happy for some time.

And also keeping me busy is the band-wagon-jumping of Why Does E=mc²? (and why should we care?) by intellectual de-jour, Professor Brian Cox and equally clever Professor Jeff Forshaw. This is a readable book and jumps straight in with the explanation of why light speed is fixed and why this means that time and distance is not. It uses the standard light-clock-on-a-train method and Pythagoras to explain the changes and this is fine. However, it then avoids the standard historical narrative of Special Relativity followed by General Relativity and all the standard means of trying to explain them and goes into a real-world example of why space-time is a signal entity using the example of the time and distance between waking up and finishing your breakfast from both your point of view and that of a passing observer. I have to admit I have had to go back and read this bit again but the promise of a beautiful revelation at the end of it draws you in to quite happily repeating the difficult bits. I am hopeful for a full path to understanding all of relativity rather than just isolated bits of the equations.