On the train

Simon waiting patiently as our train was halted for over an hour due to the extreme heat: “If you pick four atoms from the Universe at random, then I would expect you to pick only 26 particles, including 12 up quarks, 9 down quarks and five electrons. This is because the Universe is made of approximately 75 percent hydrogen and approximately 25 percent helium atoms. So you get one proton and one electron for each hydrogen atom, and two protons, two neutrons and two electrons for each helium atom. A proton is made up of up, up and down quarks and a neutron is made up of down, down and up quarks”.