Friday, June 19, 2015

Iron Skillets are the Reason You Exist

I had an interesting discussion with a chemist today. They talked about how at one point had the entire periodic table of elements memorized, could recognize molecules in peoples names, and could rattle off most of the information on the periodic table without too much trouble. So I thought I would take a shot at stumping them.

"Do you know where all of the elements on the periodic table came from?" I said. They looked at me somewhat puzzled. "What do you mean where did they come from?" I could see the confusion on their face. Maybe this is the first time they have ever thought about this, maybe they just assumed that these things just always were. But, that's not the case.

I also had a feeling the person, even though trained in chemistry, may not know the answer to this. The reason is because origin of the elements on the periodic table is not rooted in chemistry, rather astrophysics.

The most abundant element in the universe is hydrogen, by far! Hydrogen makes up about 75% of the mass of the entire universe. The second most abundant element is helium, which makes up almost all of the remaining 25%. That means that elements 1 and 2 on the period table make up 99% of the entire mass of the universe. Elements 3-118 make up 1% of the mass. Without getting into any technical detail, it's evident that hydrogen and helium were the only 2 elements present at the time of the Big Bang (or formed within 10 minutes or so of the Big Bang through a nucleosynthesis process, to be pedantic). In laymen's terms, at the time of the Big Bang there was a LOT of really hot, intense energy, and within minutes the energy was converted into matter (specifically hydrogen and helium). For more information on how energy converts to matter and matter converts to energy, see Einstein's theory of relativity which conclusively demonstrated that energy is matter (E=M).

Great so now we have hydrogen and helium. Where did every other element come from? Take a guess... from hydrogen and helium. That's right, everything from carbon to gold to oxygen to iron to xenon comes from just hydrogen and helium. But how? How can oxygen become gold, etc?

The short answer is, it can't. Well, not on its own. Helium tends to stay helium and hydrogen tends to stay hydrogen thanks to electromagnetism. So when two differing atoms approach one another they don't fuse together, they repel sort of like the repelling ends of a magnet (well exactly like that, actually). What is required for atoms of two different type to overcome electromagnetic repulsion in order to fuse together and create a new element? A lot of heat and pressure. A lot.

Once you have enough pressure to force these atoms close enough past the point of electromagnetic repulsion, together they start trading protons and becoming new elements. Two hydrogen atoms (atomic number 1) form together to create helium (atomic number 2). A helium atom (2) combines with another hydrogen atom to form lithium (3). So on and so forth.

So where does this fusion happen? Mainly in 2 places; stars and supernovae. The core of a star is a nuclear reactor on a grand scale. The energy and heat given off from stars is the result of nuclear fusion happening in its core. It's hot outside today. Thanks nuclear fusion!

Atoms are being smashed together constantly inside of a star to create newer, heavier elements with more protons. Helium smashes together to become lithium, lithium mashes up to become beryllium, then boron, then carbon, then nitrogen, then oxygen, etc. Each time two atoms fuse, an obscene amount of energy gets released (literally an atomic bomb).

This process repeats, and repeats and repeats. So every element on the periodic table from hydrogen to iron forms inside the core of a star. And with every fusion the star continues burning like a champ. But when the fusion process gets around to iron, something lethal to the star happens. Iron atoms don't play nice. Iron does not fuse with other elements like its predecessors. When iron starts forming inside the star, it's a death sentence. The star stops losing the energy gained from fusion, because iron has caused fusion to slow down, and eventually stop.

Star Killer
Thanks a lot, iron. Forget the "Red Matter" from Star Trek lore. You want to destroy a star? Your iron skillet did that.

But you should be thankful to your iron skillet, without it you probably wouldn't be here. After fusion stops in a star, the star collapses onto itself. Stars that are the right size detonate into a supernova. Just about all other forces of nature stand in awe of the fury and power of a supernova. Whereas the fusion inside the core of star, literally cannot produce enough energy to fuse anything to iron, a supernova has so much energy it creates every element on the periodic table from number 27 to 118... all at once.

Mother Nature's way demonstrating your insignificance.
To give you some sense of just how much energy is released in a supernova, when a star goes supernova, it temporarily outshines every other star in its galaxy combined. That's right, take the light from a hundred billion stars and for a brief moment this dying star makes them all look dim. While it's doing this, it throws all 118 elements of the periodic table out into space. Including carbon and oxygen from which you are made.

The carbon atoms in your body used to be inside the core of a star, and thanks to iron threw that carbon out into space. And now, here you are. Probably cooking eggs on your iron skillet without even taking a moment to thank it for blowing up that star for you.

Enjoy your omelette.

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