Chapter 23 postscript

Created in 1949 and first published in 1950.At that time, only four years after Hiroshima, I (and the world, I believe) underestimated the effects of low-level radioactivity on biological tissue.So I conceived of a generally radioactive Earth, with humans still living on it.At the time, I thought it was a reasonable assumption. Now that my opinion has changed, it is impossible to revise this book, because the radioactivity of the earth is the backbone of the story.I have no choice but to ask readers not to pursue it, but to appreciate (assuming you really appreciate) this story according to the logic of this book.

Isaac Asimov