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Particles in the universe come in two types, named bosons and fermions, after Satyendra Nath Bose and Enrico Fermi (“boson” is pronounced with a long ‘o’ and a hard ‘z’, to rhyme with “goes on”). Bosons include things like photons (particles of light), which can be absorbed or emitted in large quantities. Fermions include things like electrons and protons which form the building-blocks of matter. The chief distinguishing characteristic of these different types of particle is that bosons can congregate together in the same region of space and state of motion, all moving along together. Fermions, by contrast, only ever exist one at a time in any given place and state of motion. Photons in a laser beam are an example of bosons gathered together in the same motion. Electrons in different orbitals in atoms are an example of fermions avoiding one another. This leads to the fact that atoms with different numbers of electrons behave differently, which is the basis of chemistry.
Before I embark on this blog post, a few words for regular readers. I have to apologise for the blog falling dormant for a month. This was because I have been working intensely on a book (a physics textbook), and also because I have been mulling over what to write. Also, I put up quite a lot of content just before the dormant period so I hope there was enough to be going on with (see under resources/talks). Finally, regarding comments: thanks for all constructive comments. They are all much appreciated and encouraging. However it is hard to keep up with moderating them because I have had over 7000 comments in total, almost all of them spam. I hope some day to get some help with the filtering process, but until I do that the situation will continue to be slow.
The post you are reading now was prompted in part by a recent talk at the physics department here in Oxford. The talk was the 2015 Wetton Lecture, delivered by Professor Carlo Frenk, Director, Institute for Computational Cosmology, University of Durham, and it had the title
“Everything from nothing, or how our universe was made”