A Universal Recipe for Apple Pie

Nov 18, 2016

Credit Neven Mrgan (Flickr)

On this episode of Our Island Universe: How an astrophysicist would go about making an apple pie for Thanksgiving.


This Thanksgiving, many Americans will sit down around a table, partake in a great feast, and perhaps finish it off with a slice of apple pie. As my scientific hero, Carl Sagan, used to say: "If you want to make an apple pie from scratch, you must first invent the Universe."

We are a carbon-based life form, that breathes oxygen, has iron in our blood, and live on a planet that has an atmosphere that is mostly nitrogen. Where does this stuff come from?! We know that Hydrogen, Helium, and trace amounts of Lithium - the first 3 elements on the periodic table - were produced in the first 3 minutes after the Big Bang some 13.8 billion years ago. EVERYTHING else on the periodic table was produced in stars that either exploded cataclysmically, dumping the innards of elements produced in the core, or from lower mass stars that shed its outer layers into interstellar space. In the case of a supernova, the exploding star can be momentarily as bright as the whole galaxy before fading into darkness. However, the exploding material may cause a reservoir of gas and dust to collapse and form new stars! This material is now enriched with the stuff produced in the centers of massive stars. Planets may form around these new stars enriched in this stuff, and life may develop on some of these planets enriched in this material. We know that this story has played out at least once in the history of the Universe - namely us!

So the next time you're having a bad day, remember, you are literally made of star stuff!