Computronium is a material hypothesized by Norman Margolus

Norman Margolus

Norman H. Margolus is an Canadian-American physicist and computer scientist, known for his work on cellular automata and reversible computing...

 and Tommaso Toffoli

Tommaso Toffoli

Tommaso Toffoli is a professor of electrical and computer engineering at Boston University. He joined the faculty in 1995. He was born in June, 1943 in Montereale Valcellina, in northeastern Italy, and was raised in Rome. He received his doctorate in physics from the University of Rome La...

 of the Massachusetts Institute of Technology

Massachusetts Institute of Technology

The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...

 to be used as "programmable matter

Programmable matter

Programmable matter refers to matter which has the ability to change its physical properties in a programmable fashion, based upon user input or autonomous sensing...

," a substrate for computer modeling of virtually any real object.

It also refers to a theoretical arrangement of matter that is the best possible form of computing device for that amount of matter.

Computronium in popular culture

In the Hitchhiker's Guide to the Galaxy books, by Douglas Adams

Douglas Adams

Douglas Noel Adams was an English writer and dramatist. He is best known as the author of The Hitchhiker's Guide to the Galaxy, which started life in 1978 as a BBC radio comedy before developing into a "trilogy" of five books that sold over 15 million copies in his lifetime, a television...

, the entire Earth is portrayed as programmable matter; a computer designed to find the question to the Answer to Life, the Universe, and Everything.

Charles Stross

Charles Stross

Charles David George "Charlie" Stross is a British writer of science fiction, Lovecraftian horror and fantasy. He was born in Leeds.Stross specialises in hard science fiction and space opera...

 also uses the term in Accelerando.

In the Revelation Space

Revelation Space

Revelation Space is a 2000 science fiction space opera novel by Welsh author Alastair Reynolds. It was the first novel set in the Revelation Space universe, although the then-unnamed universe had already been established by several published short stories....

 books, by Alastair Reynolds

Alastair Reynolds

Alastair Preston Reynolds is a British science fiction author. He specialises in dark hard science fiction and space opera. He spent his early years in Cornwall, moved back to Wales before going to Newcastle, where he read physics and astronomy. Afterwards, he earned a PhD from St Andrews, Scotland...

, a neutron star

Neutron star

A neutron star is a type of stellar remnant that can result from the gravitational collapse of a massive star during a Type II, Type Ib or Type Ic supernova event. Such stars are composed almost entirely of neutrons, which are subatomic particles without electrical charge and with a slightly larger...

called Hades is converted into a massive super computer. The neutronium substance of Hades would therefore be computronium.