[Michael Burke]

Michael Burke asked the Naked Scientists:

Regarding your answer to a question about the earth getting heavier by adding people, you seemed to have overlooked e=mc2 and photosynthesis, where more than a little bit of sunlight is converted to plant matter, and that into people.

There was an experiment long ago wherein a tree was grown in a carefully weighed pot of soil. At some point the tree was removed, the dirt removed from the tree, and the tree and soil dried to remove moisture. While the tree mass weighed some number of pounds, only an ounce or so of soil minerals was missing. The mass of the tree had come from the photosynthesis of light into matter.

Cordially,

Michael Burke

[blakestyger]

No  - it's just a redistribution of elements. If you're referring to photosynthesis - the reduction of carbon dioxide to form sugars - the only incoming component is the ultraviolet light from the sun. Everything else comes from the soil and atmosphere.