The Space Elevator Will Be Built About 50 Years After Everyone Stops Laughing

Arthur C. Clarke? Arthur Kantrowitz? Apocryphal?

Dear Quote Investigator: Science fiction luminary Arthur C. Clarke described the audacious idea of building an elevator from the surface of the Earth straight up into space and beyond geostationary orbit in his 1979 novel “The Fountains of Paradise”. The megaproject would require extremely strong lightweight material, and some engineers and scientists have questioned its feasibility. Clarke puckishly said that the space elevator would be built a few decades after people stopped laughing. Would you please help me to find a citation?

Quote Investigator: In 1979 Arthur C. Clarke addressed the 30th International Astronautical Congress and surveyed the concept of a “space elevator” which has also been called an “orbital tower” or “heavenly ladder”: 1

What I want to talk about today is a space transportation system so outrageous that many of you may consider it not even science-fiction, but pure fantasy. Perhaps it is; only the future will tell. Yet even if it is regarded as no more than a ‘thought-experiment’, it is one of the most fascinating and stimulating ideas in the history of astronautics.

Apparently, Clarke’s vivid quotation was modeled after an earlier remark made by Arthur Kantrowitz who was an influential proponent of an innovative idea for space transportation called laser propulsion. Clarke speculated about the time needed to develop the space elevator:

And when will we have that? I wouldn’t like to hazard a guess, so I’ll adapt the reply that Arthur Kantrowitz gave, when someone asked a similar question about his laser propulsion system:

The Space Elevator will be built about 50 years after everyone stops laughing.

QI has not yet located the earlier comment by Kantrowitz about laser propulsion.

There is some evidence that Clarke later endorsed a shorter time as indicated in the selected citations in chronological order listed below.

In 1984 Clarke published “Ascent to Orbit”, a collection of his technical writings. The quotation above was included in an article titled “The Space Elevator: ‘Thought Experiment’, or Key to the Universe?” 2

In 1985 “The Atlantic Monthly” printed an article titled “Business in Space” by David Osborne that included the quotation: 3

It could carry people to facilities in geosynchronous orbit without the enormous expense of energy entailed by, say, a moon launch. Or, acting as a kind of sling, it could hurl space vehicles beyond the reach of gravity for long voyages. Clarke predicts that the space elevator will be built “about fifty years after everyone stops laughing.”

In 1999, just before the new millennium, Scot Lehigh, a journalist with the “Boston Globe”, wrote about a collection of futuristic predictions such as fusion power, maglev trains, moon colonies, and a space elevator: 4

That was a nostrum Clarke tried to popularize in the 1970s and ’80s. “Clearly, if a satellite can remain poised forever above the same spot on the equator, then, in principle, it should be possible to lower a cable from orbit to Earth, performing an Indian rope trick 36,000 kilometers high,” he wrote. Cagily vague on the time line, he said it would happen “50 years after everyone stops laughing.”

In 2003 Clarke and his co-author Stephen Baxter published the novel “Time’s Eye”. The 2005 reprint edition included an interview with the two authors during which Clarke updated his quotation and changed the number of years from fifty to fifteen: 5

Q: Sir Arthur, the New York Times recently ran a long article about an idea near and dear to your heart: the space elevator. When do you think we’ll see this dream, the subject of your 1980 Hugo Award-winning novel The Fountains of Paradise, become a reality?

AC: About fifteen years after everyone stops laughing!

Clarke died in March 2008, and in July 2008 “The Independent on Sunday” based in London printed a piece about his posthumous book “The Last Theorem”: 6

The novel outlines a plot by aliens to invade Earth; an astronomy student’s obsession with Fermat’s last theorem; a UN bombing campaign; and another of Clarke’s predictions – space elevators. The concept involves a huge cable connecting the Earth to orbital altitude, along which elevators can be launched using electromagnetic vehicles.

“I’m often asked when I think the space elevator will be built,” Clarke said in his last interview. “My answer is about 10 years, when everyone stops laughing.”

In 2009 Michel van Pelt published “Space Tethers and Space Elevators” which included two versions of the saying ascribed to Clarke: 7

In the early 1990s, Clarke was asked when the space elevator would become a reality. He answered, “Probably about 50 years after everybody quits laughing.” At the Space Elevator 2nd International Conference held in Santa Fe in 2003, he had become more optimistic, updating his estimate to “10 years after everybody stops laughing … and I think they have stopped laughing.”

In conclusion, Arthur C. Clarke did make the wry space elevator comment with a fifty year time period in 1979. Later he revised the period to fifteen years. There is also some indirect evidence that he employed a version with ten years.

(Great thanks to Jason T. Wright whose inquiry led QI to formulate this question and perform this exploration.)


  1. Website: Island One Society, Reprint Article: Year: 1981, Journal: Advances in Earth Oriented Applications of Space Technology (the website incorrectly used the words “applied” and “technologies” in the journal name), Volume 1, Article Title: The Space Elevator: ‘Thought Experiment’, or Key to the Universe?, Author: Arthur C. Clarke, Note: Address to the XXXth International Astronautical Congress, Munich, 20 September 1979, Start Page 49, Quote Near Final Page, Publisher: Pergamon Press Ltd., U.K. Website description: Island One Society website operated by Dale Amon. (Accessed on June 8, 2017; QI has not verified the article in the original journal) Page 1 link Page 3 link
  2. 1984, Ascent to Orbit: A Scientific Autobiography: The Technical Writings of Arthur C. Clarke, Chapter 21: The Space Elevator: ‘Thought Experiment’, or Key to the Universe?, (Note states: Published in Advances in Earth Orientated Applications of Space Technology, Vol. 1, Num. 1, 1981, pg. 39-49; the word “orientated” should have been “oriented”), Start Page 183, Quote Page 193, A Wiley-Interscience Publication: John Wiley & Sons, New York. (Verified with hardcopy)
  3. 1985 May, The Atlantic Monthly, Business in Space by David Osborne, Start Page 45, Quote Page 51, Column 1, The Atlantic Monthly Company, Boston, Massachusetts. (Verified with hardcopy; also available via scans in 1985 Congressional Subcommittee hearing on “Patents in Space” in HathiTrust) link
  4. 1999 November 5, Santa Cruz County Sentinel, The millennial question: Where’s that amazing future? by Scot Lehigh (The Boston Globe), Start Page A1, Quote Page A10, Column 1, Santa Cruz, California. (Newspapers_com)
  5. 2005 Copyright, Time’s Eye by Arthur C. Clarke, Stephen Baxter, Series: Book 1 of Time Odyssey, Section: Interview with Arthur C. Clarke and Stephen Baxter, Quote Page 370, Del Rey: Ballantine Books, New York. (Google Books Preview)
  6. 2008 July 6, The Independent on Sunday, Article: Arthur C Clarke’s last words – from beyond the stars – News: The science fiction master’s final novel, the product of a collaboration, is soon to be published posthumously, Byline: Paul Bignell, Page 18 and 19, London, England. (NewsBank Access World News)
  7. 2009, Space Tethers and Space Elevators by Michel van Pelt, Quote Page 57, Copernicus Books: Springer Science & Business Media, New York. (Google Books Preview)