Decay Modes

Source - xkcd
Rollover text - Unlike an Iron Age collapse, a Bronze Age collapse releases energy, since copper and tin are past the iron peak on the curve of binding energy.

...so, it's funny because...

We haven't taught nuclear decay or nuclear chemistry in my first year chemistry class at Princeton in quite a few years since it was taken out of the Ohio chemistry curriculum and off of the AP exam quite a few years ago. We leave that nuclear stuff to the PHS physics department.

With all that being said, I remember the top row of decay mechanisms, and they're real. 

• Alpha decay sees the nucleus shedding two protons and two neutrons.
• Beta decay shows a neutron turning into a proton while the nucleus ejects an high-energy electron, aka a beta particle. That drawing helps us to know that Randall is drawing neutrons as shaded-in circles and protons as the 'white' or 'hollow' spheres.
• Gamma has the nucleus rearrange its particles - protons and neutrons, known collectively as baryons (though there are more baryons than just protons and neutrons.)
• Electron capture is just what it says: an electron is drawn into the nucleus, turning a proton into a neutron.
• Positron emission is also a proton turning into a neutron, but in this case it releases a position, effectively an electron with a positive charge.
• Neutron emission is pretty self-explanatory as a neutron leaves the nucleus.

Then we get to the made-up ones which lead to the jokes. For some of these, I did rely on explainxkcd to get the gist.

• Baryon panic would be insanely energetic, requiring all of the protons and neutrons to spontaneously separate, requiring a massive amount of energy to be absorbed by the nucleus.
• Omega decay is the assumed progression of alpha, beta, and gamma decay - omega being the last Greek letter in the alphabet. I guess since alpha, beta, and gamma decay give off increasingly energetic particles, omega decay would somehow give off the most energetic particle and cause death?
• Electron wilt seems to show the electrons just stopping their motion around the nucleus, wilting like a flower.
• One big nucleon shows all of the protons and neutrons 'congealing' into a single nucleon, the generic term for a particle in the nucleus. The is, I guess, kind of like a Bose-Einstein condensate but for the nucleus.
• Fungal decay gets nuclear decay and biological decay muddled up with the nucleus sprouting mushrooms.
• Collapse due to invasion by the sea peoples seems to refer to something that supposedly happened to the eastern Mediterranean during the late Bronze Age. I dunno. I had to look it up.

The rollover makes reference to the fact that the nuclear binding energy for iron-56 is the highest on the periodic table (at least among common isotopes). This is why large stars never make anything beyond iron-56 in their life cycle until they go supernova. And since bronze is made of tin and copper - both beyond iron-56 on the periodic table - a collapse of those elements releases energy according to Randall.

It's all some pretty esoteric stuff today.

Don't worry if you don't get it.