Earth (Foundation universe)

This article is on the history of Earth, as presented in Isaac Asimov's Foundation series, Robot series, and Empire series.

Humans from Earth colonize the Spacer and, later, Settler planets; an anti-Earth plot causes the planet's crust to become radioactive, greatly reducing its population. Many small empires rise and fall throughout the Milky Way Galaxy as various worlds trade with and fight each other. Over time one planet, Trantor, founds a true Galactic Empire. By then Earth is only one of millions of member worlds, and the radioactivity makes it a quarantined backwater; by 827 G.E. (Galactic Era, the number of years after the empire's founding), the setting of Pebble in the Sky, only 20 million people live on Earth. Most non-Earthlings are skeptical of the scholarly theory that the obscure planet is the original home of all humans, believing that humans evolved on many planets simultaneously. By 12000 G.E., the setting of the Foundation series, although many believe that humanity originated on one planet, Earth is one of several candidates.

But why is Earth radioactive? In the Afterword to "Grow Old Along With Me" in The Alternate Asimovs, Asimov explains:

I gave the Earth of the future a radioactive crust, at least in spots, yet it had a remnant of life and humanity clinging to it. Clearly, I meant this to be taken by the reader as the result of a nuclear war in our future; and the story's past... It is of crucial importance to the plot.

This was retained when "Grow Old Along With Me" became Pebble In The Sky, published in 1950. When Asimov returned to his future history with Foundation's Edge (1982), he no longer thought a nuclear war could make the crust radioactive without destroying all life. Instead, he assumed that the crust of the planet was deliberately made increasingly radioactive.

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