We are stardust

The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of starstuff.

Carl Sagan (h/t to commenter remanandhra)

There’s a long gap between the origin of the universe, the first stars, and early galaxies, and the origin of our Solar System and our planet Earth. If we were using a linear scale for our calendar, the Solar System would get started in September. Even on our logarithmic scale, Sun and Earth wait until late January. A spiral galaxy like the Milky Way is an efficient machine for turning dust into stars over many billions of years. But the earliest stars it produces are poor in “metals” (to an astronomer, anything heavier than helium is a metal). It takes generations of exploding stars producing heavier elements and ejecting them into space before a star like the Sun — 2% metal – can form.

Alchemists thought they could change one element into another – lead into gold, say. But it takes more extreme conditions than in any chemistry lab to transmute elements. The heart of a star makes heavy elements out of hydrogen and helium; it takes a supernova to make elements heavier than iron. So it’s literally true, not just hippy poetry, that “we are stardust” (at least the part of us that isn’t hydrogen).


4 thoughts on “We are stardust


    Just a thought.. Would an inverse square mapping be appropriate, rather than log, because it reflects our human understanding of distance?


    1. logarithmichistory Post author

      Interesting suggestion, but … with an inverse square function, the last day of the year would cover over 100,000 years, which is a lot of prehistory and history to cram into one day. So logarithms it is.


  2. Pingback: We are upside-down bugs | Logarithmic History

  3. Pingback: We are MacApes, O’Monkeys, and Ben-Reptiles | Logarithmic History

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