X Stands for Unknown
# X Stands for Unknown

'X' Stands for Unknown is a collection of seventeen nonfiction science essays written by Isaac Asimov. It was the seventeenth of a series of books collecting essays from The Magazine of Fantasy and Science Fiction, these being first published between January 1982 and May 1983. It was first published by Doubleday & Company in 1984.

## Contents

* Physics
   * 1 Read Out Your Good Book in Verse (May 1982)
   * 2 Four Hundred Octaves (June 1982)
   * 3 The Three Who Died Too Soon (July 1982)
   * 4 X Stands for Unknown (August 1982)
* Chemistry
   * 5 Big Brother (September 1982)
   * 6 Bread and Stone (October 1982)
   * 7 A Difference of an 'E' (November 1982)
   * 8 Silicon Life After All (December 1982)
* Astronomy
   * 9 The Long Ellipse (January 1982)
   * 10 Change of Time and State (April 1982)
   * 11 Whatzisname's Orbit (March 1982)
   * 12 Ready and Waiting (February 1983)
   * 13 Dead Centre (April 1983)
   * 14 Out in the Boondocks (May 1983)
* Mathematics
   * 15 To Ungild Refinèd Gold (January 1983)
   * 16 The Circle of the Earth (February 1982)
   * 17 The Armies of the Night (March 1983)

## Reception

Dave Langford reviewed X Stands for Unknown for White Dwarf #79, and stated that "If you're scientifically literate you'll find the interesting bits buried in over-familiar stuff (though I always cheer Asimov when he stomps the crackpots). If not, you probably don't read books like this. That's showbiz."

## Reviews

* Review by Edward James (1985) in Paperback Inferno, #55
