“We are made of star-stuff. We are a way for the cosmos to know itself.”

If you aren’t sure what this has to do with you, and the things that bother or inspire you, bear with me. I think it will come back together at the end.

Someone told me the other day, “we are all made of stardust”. It wasn’t something I’d heard before, so I investigated.

Who said it first? It seems like lots of people said the same thing in slightly different ways, look here ( if you want to know more. Possibly the most famous is Carl Sagan, who wrote in 1973 (The Cosmic Connection), “We are made of star-stuff.”

Is it factual? I read this (, this ( and this ( It seems like the answer is mostly yes. Apart from hydrogen, which is big bang dust, pretty much every other atom in our bodies is made of stardust. If we count by mass, rather than number of atoms, we are around 95% stardust.

Going deeper, my research took an interesting turn (with apologies to my husband, who isn’t that impressed with questions about atoms before 7am), when I read this page of the Guardian’s Notes & Queries section ( The key point for me came from the words of someone of the name hippo42, so I’ll give you those in full:

“Atoms of a given isotope of an element – for example, Carbon-14 – are not merely indistinguishably similar, but identical. No matter how accurately you measure the size, shape, mass or any other attribute of an atom, it is in principle impossible to find any difference that could lead you to say that a particular atom was the atom you observed on some other occasion.

It seems almost impossible to doubt the truth of this proposition; but it is fully impossible for me to comprehend it. I can glibly say that atoms of a given isotope are not distinct objects, that they partake of a common identity, from one end of the universe to the other – but what this means, I simply cannot grasp. Can anyone?”

I didn’t even know what an isotope was. This article by Matt Strassler ( helped me a lot. One of Matt’s responses to a comment was this thought, which I’m paraphrasing: if it were theoretically possible to swap two identical atoms, one in my body, one in a star, they would take on the role of the other.

In answer to hippo42’s question, yes, I can grasp this! A grand claim? No, it’s our birth right. Watch this clip video (  from Carl Sagan’s 1980 TV series Cosmos. At 2:25 he says, We are made of star-stuff. We are a way for the cosmos to know itself.”

The atom isn’t mine. It’s not branded or stamped, you can’t examine it to find a part of my personality. The atom, is neutral. It only does what it does because of where it is. If you could swap my atoms with yours, you’d still be you, and I’d still be me.

We are all made of the same stuff, exactly the same stuff. The reason I behave the way I do, is the same reason that you behave the way you do – because it makes sense to me in the moment. If your atoms were in me, they’d be colluding in that behaviour too. The only difference is in what makes sense at any moment.

Now I’m aware of that, how much time do I need to spend trying to correct a behaviour that looks wrong to me, or encourage a behaviour that seems right? What if I can talk to the core of you, the bit that defines what makes sense in the first place? From there, you are going to have a very different perspective on the joys and challenges of your own life. Insight and realisation in a practical way become more likely.

The results of my research? Yes, it’s pretty accurate to say we are made of stardust.

Here it all comes back together. From your spirit, from your core, you live a life, holding a collection of atoms as old as the stars. As does everyone. What we have in common is so much more than what divides us.

Starry Sky

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