Prediction is hard, especially that of the future. Psychics and would-be prophets often give exact details of what is about to happen and when the day passes, their followers conveniently forgot they ever said anything of the kind. And they remember mainly those that happened to come true.

However, would-be psychics are hardly the only people prone to making wrong conclusions — scientists may make inopportune predictions based on faulty data or conservatism.

Many predictions have been conventionally vague but that is not the case of the following ones:

;1761

;April 5:destruction of London according to a soldier named Bell.
;1899
;.:"Everything that can be invented has been invented." - attributed to Charles H. Duell, director of the US Patent Office
;1919
;.:Conjunction of 6 planets would make sun explode, according to meteorologist Albert Porta
;1925
;.:End of the World according to Jehovah's Witnesses
;1943
;.:"I think there is a world market for maybe five computers." - Thomas Watson, chairman of IBM
;1977
;.:"There is no reason anyone would want a computer in their home." - Ken Olson, founder and president of Digital Equipment Corporation
;1981
;.:"640K ought to be enough for anybody." - attributed to Bill Gates
;.:Kingdom of Heaven according to the Unification Church (rescinded).
;1982
;.:End of the world according to Pat Robertson.
;.:Jupiter effect, astronomical alignment of planets on the one side of the sun would cause lethal solar flares - according to US astronomers John Gribben and Stephen Plagemann.
;1985
;.:"(by 1985) Machines will be capable of doing any work Man can do." - Herbert Simon, US Nobel laureate
;1988
;.:Rapture according to The Late, Great Planet Earth by Hal Lindsey
;1991
;.:End of the world (attributed to Mother Shipton)
;1998
;May 31:Rapture according to evangelist Marilyn Agee
;July 5:X-Day according to the Church of the SubGenius
;2003
;May 15:end of the world according to Pana Wave Laboratory (later changed to May 22)

Fictional predictions

Science fiction is concerned about the future. However, science fiction writers are not any more perceptive that others - stories placed in the year 5000 used to have computers that were the size of an office building.

It is, of course, rarely true that science fiction writers are seriously attempting prediction - the needs of the story are usually the primary concern, and science fiction stories are often more about the present in which they are written than the future in which they are supposedly set.

Here, nevertheless, are some notable fictional visions of the-future-that-never-was:

;1984

;.:Winston Smith, a secretly rebellious file clerk in the Ministry of Truth, is arrested and tortured by Big Brother (Nineteen Eighty-Four by George Orwell)
;1997
;August 29:Human civilization is destroyed by Skynet (The Terminator; Terminator 3: Rise of the Machines, the first sequel released after 1997, claimed that the advent of Skynet had been delayed, but not prevented, by the events of the first two movies)
;November 5:The first recorded appearance of the mysterious terrorist known as "Codename V" in Westminster, London. During the next year he launches a series of elaborate attacks against the fascist regime (which had ruled England since the nuclear war of 1988), causing increasing confusion and unstability, which ultimately brings the regime down (V for Vendetta by Alan Moore and David Lloyd).
;1999
;.:Atomic explosions drive the moon from its orbit, leaving Moonbase Alpha to fend for itself. (television series Space: 1999)
;2000
;.:Massive overpopulation (Make Room, Make Room by Harry Harrison)
;2001
;.:An extra-terrestial obelisk found on the moon, prompting an investigation flight to Jupiter, which is sabotaged by HAL 9000 (2001: A Space Odyssey by Arthur C. Clarke and Stanley Kubrick)