Wood comes from thin air
Richard FeynmannPeople look at trees and they think it comes out of the ground. The plants grow out of the ground. But if you ask where the substance comes from, you find out they don't know.
“Where do they come from? The trees come out of the air?”
They surely come out of the air.
The carbon dioxide in the air goes into the tree and it changes it, kicking out the oxygen and pushing the oxygen away from the carbon and leaving the carbon substance with water.
Water comes out of the ground, you see, only it had to get in there. It came out of the air, it came down from the sky. So, in fact, most of a tree, almost all of the tree is out of the air. There's a little bit from the ground, some minerals and so forth.
Now, of course I told you the oxygen and carbon stick together very tight. How is that the tree is so smart to take the carbon dioxide —which is carbon and oxygen nicely combined— and undo that so easy? Ah! Life! Life has some mysterious force! No! The sun is shining, and is this sunlight that comes down and knocks this oxygen away from the carbon, so it takes sunlight to get the plant to work!
And so the sun, all the time, is doing the work of separating the oxygen away from the carbon. The oxygen is some kind of terrible by-product, which it spits back into the air, and leaves the carbon and water and stuff to make the substance of the tree.
And then when we take the substance of the tree and stick it in the fireplace and there's all the oxygen made by these trees and all the carbons would much prefer to be close together again. And once you let the heat to get it started it continues and makes an awful lot of activity while it's going back together again.
And all those nice lights and everything comes out and everything is being undone you're going from carbon and oxygen back to carbon dioxide. And the light and heat that's coming out, that's the light and heat of the sun that went in, so it's sort of stored sun that is coming out when you burned a log.
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