stardust

“We are stardust.
Billion year old carbon.
We are golden.”
  – Joni Mitchell, “Woodstock”

Did you ever really wonder where you came from? Not relatives and ancestors and family trees, but the stuff that’s inside your body. And I mean even deeper than bones, organs, and muscles. Down to the molecules and atoms.

Where did those come from and how were they created?

It very early in the morning as I write this. It’s raining and the sky is dark and cloudy. But the stars are out there and I am traveling back in my mind to a time when the universe was very different.

Big bang. About 3 seconds long. And then that new universe expands and cools to a state where subatomic particles assembled into atoms. Or at least, so say most physicists. I’ll take it on faith for now, like knowing that those stars are out there tonight even though I can’t see them.

Hydrogen atoms formed first and then after a mere 300 million years, they clump together under the force of gravity, the pressure increases, they heat up (15 million degrees F) and fuse their nuclei together.

Now we move to number two on the periodic table of elements. Helium. That fusion releases a lot of energy, some is converted into light energy (see E=mc2 ) and we have a star.

I am simplifying to a ridiculous degree, but allow me for the purposes of telling the story.

A star produces all of the elements up to iron in the periodic table . Iron has 26 protons in its nucleus and to make higher elements, fusion requires more energy than it produces.  So, that star creates, fusion ceases and the core begins to cool. Eventually, that cooled core no longer expands and gravity quickly collapses the star.

It implodes. Supernova. What happens is not totally known but there is enough energy to now fuse some atoms into Nickel, Krypton, Gold, Uranium and other higher elements.

The stardust travels throughout the universe. One day it will clump together with other stardust and give birth to a new star. Circle.

Aside from hydrogen, all the elements can be viewed as stardust. The parts of our body that are not hydrogen are stardust. That is estimated to be about 40%.

Wish upon a star. Think of them as ancestors.


Want to know more about the science here? Want to know the math to arrive at that 40%? Check out PhysicsCentral.com

You can Download the “How much of the human body is made up of stardust?” poster illustrated above format_pdf  and order other posters

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