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Particle Physics and Pony Fiction Experimentalist

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Universal Building Blocks · 12:18am Mar 16th, 2014

Ever wondered how to explain primordial and stellar nucleosynthesis to six year olds?


Well on the off chance that you are ever called upon to perform such a duty, let me tell you the best way.

Twilight builds a model of an argon nucleus.

All you need is a pile of Lego bricks of two colours – say red and yellow. The yellow ones are the up quarks, the red ones are the down quarks. If you want, you can throw in a few more bricks to represent the electrons and neutrinos, but they're not so important at this stage.

All the Universe is made from these elementary building blocks.

We begin just a fraction of a second after the big bang, when the Universe was a hot soup of elementary particles. Then it cooled, so the quarks could stick together to form protons and neutrons. Two yellows and a red = a proton. Two reds and a yellow = a neutron.

Three minutes later, when the Universe had cooled further, our protons and neutrons stick together to form simple nuclei. Clip a proton and a neutron together, and you have a deuterium nucleus. Add another proton, and it turns into helium-3. Or join two protons, and two neutrons and you make helium-4.

For the next hundred million years, the Universe was just full of light nuclei: hydrogen and helium, and maybe a bit of lithium. Then stars formed, which can do nuclear fusion, which leads to heavier elements. So you can now start stacking your light nuclei into heavier particles. Stack three helium-4 nuclei and you make carbon. Keep going, and with a supernova or two, you can get through the whole periodic table.

I've played this game many times, and it never fails to engage young children. I've done it at a science fair alongside far more glamorous stall-holders like Google and Siemens, and watched the young visitors ignore them and make for the Lego. I've seen children play happily for hours with a Lego kit with only two different types of brick.

This is of course, of no surprise to the parents of young children, who know very well that you don't need sophisticated toys to keep them happy. Just as well as the Lego marketing team know that to maximise sales you need an ever-changing range of specialized kits.

Twilight finds the Higgs Boson.


Comments ( 4 )

This sort of thing is why I follow you. I'm definitely going to have to remember this. It seems obvious in hindsight. How better to explain the building blocks of the universe than with... well, building blocks?

Something that always confuses me, when they say teh universe started with equal amounts of matter and antimatter, but one in a million or so excess of matter. that means there would be a million fold mass energy left over, and the universe wouldve seriously gravitationally collapsed. If however standard model of decay of a proton is true, and it decays into a pion, antipion, and anti electron, which Id like to see the quark gluon graph for, that means a hydrogen atom can be slit into equal parts matter and antimatter. So its more of a rate of reaction imbalance, not intitial products.

I really like the 2 colour blocks, but to do the full E8 would take 240 colours, shapes, pin counts?:twilightoops:

But but but stars in Equestria are most likely made out of magic, they wouldn't have a model of stellar nucleosynthesis! :raritydespair:

I read all of your stories and blogentries. You forgot Beryllium. Indeed, All of the Hydrogen, Lithium, and Beryllium are primordial:

Much of the Boron is primordial too, but cosmic rays can build it up from Beryllium or spall Carbon for making Boron.

One can point to a LithiumBattery and state that the Lithium is 1.38*10^10 years old and formed when the universe was only single-digits of minutes old.

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