Arthur Kantrowitz? Gerard K. O’Neill? Timothy Leary? Arthur C. Clarke? Anonymous?
Question for Quote Investigator: Grand futuristic projects such as the following four examples have been greeted with a mixture of hope, excitement, skepticism, and derision:
(1) Laser propulsion systems for spacecraft
(2) Space-based solar power systems
(3) Space habitats with thousands or millions of people
(4) Space elevators on the Earth or the moon
A proponent was asked to give a timeline for the development of one of these advanced technological systems. The reply was ingenious:
You’ll have the result ten years after you’ve stopped laughing.
This statement has been attributed to U.S. physicist Arthur Kantrowitz, U.S. physicist Gerard K. O’Neill, U.S. psychologist Timothy Leary, and English science fiction author Arthur C. Clarke. Would you please explore this topic?
Reply from Quote Investigator: The earliest match found by QI appeared in “The CoEvolution Quarterly” in September 1975. The clever response was attributed to Arthur Kantrowitz by Gerard K. O’Neill.
Kantrowitz was the longtime director of the Avco-Everett Research Laboratory. He and his colleagues made advances in multiple technologies, e.g., supersonic wind tunnel design, magnetohydrodynamic power generation, superconducting magnets, and laser propulsion.1
O’Neill was a Professor of Physics at Princeton University who pioneered particle storage rings for high-energy physics. He also designed space habitats and advocated for space manufacturing. In 1975 O’Neill was interviewed by editor and entrepreneur Stewart Brand who asked him about the timeline for developing a space habitat housing thousands of people. O’Neill presented the words of Kantrowitz. Boldface added to excerpts by QI:2
Arthur Kantrowitz, the president of AFCO-Everett was out visiting us a few days ago. He happens to be quite enthusiastic about this work, and he says that his answer for things of that kind is to say, “You’ll have the result ten years after you’ve stopped laughing,” which is I think, a pretty good answer.
The most responsible answer I could give is to say that if I really had the responsibility for getting it done by a certain time and the authority to do it in what I would consider the right way, then I would be willing to make a very strong commitment that it could be done in 15 years from time-zero. Whatever that time-zero is.
QI believes this saying should be credited to Arthur Kantrowitz although the evidence is indirect. QI has not yet found a citation containing the quotation directly from Kantrowitz.
Below are additional selected citations in chronological order.
In 1977 the interview with O’Neill was reprinted in the book “Space Colonies” edited by Stewart Brand. Thus, the quotation ascribed to Kantrowitz achieved further distribution.3
In January 1977 journalist William Overend interviewed psychologist Timothy Leary in the “Los Angeles Times”. Leary advocated for space migration and life extension research. Leary credited O’Neill with the saying:4
“On a shrinking planet with a growing population, we can only play the old mammalian games of politics and territory. The truth is, we can’t afford to live longer down here. We need a new frontier.”
And when will this actually happen?
“Gerard O’Neill is the Princeton physicist who is the leading expert on space colonization,” Leary says. “He designed some of the collision rings that are used in high-energy particle research, and he’s been working on this with NASA. His answer is that it will happen 10 years after you stop laughing.”
In May 1977 an editorial in “The Globe and Mail” of Toronto, Canada ridiculed a futuristic proposal by Gerard O’Neill for manufacturing solar power collectors in space using material extracted from the moon.5 The following week a letter writer disagreed with the skeptical stance of the newspaper and quoted an unnamed proponent:6
One of the project’s supporters was recently asked how quickly a space-manufacturing system could be operational. He replied, “Ten years after you stop laughing.” Well, I guess, thanks to The Globe and other similar press reaction, we can keep laughing a while longer. Too bad.
The BBC broadcast a television series titled “Spaceships of the Mind” which discussed space habitats and space factories. In June 1978 a newspaper in Coventry, England published a review of an episode which highlighted an instance of the quotation although the speaker was unnamed:7
But the film’s strong conclusion that the science-fiction world may be close at hand was tersely summed up by one commentator.
Asked how soon mankind could start using minerals from space, he replied: “Ten years after you stop laughing about the idea.”
Also, in June 1978 “The Listener” magazine of London reviewed an episode of the same BBC television series and reprinted the quotation:8
But here I play into the hands of one of the experts who, when asked when raw materials in space might start becoming valuable to earthlings, said: ‘Ten years after you stop laughing.’
Also, in 1978 British science writer Nigel Calder published a companion book to the BBC series titled “Spaceships of the Mind”. Calder attributed the saying to Kantrowitz:9
So perhaps I should say a little more about the nature of big ideas. They are not, in the first instance at least, goals in a prescriptive sense — barely even projects. They are more like invitations which people can accept or decline.
An American engineer Arthur Kantrowitz caught the spirit of the big idea with his standard answer for those who asked how soon space might be clearly shown to create new hope for mankind. ‘Ten years after you stop laughing,’ he would tell them.
In 1979 prominent science fiction author Arthur C. Clarke addressed the 30th International Astronautical Congress and surveyed the concept of a “space elevator”. Clarke’s speech was printed in the journal “Advances in Earth Oriented Applications of Space Technology” in 1981. Clarke spoke about when a “space elevator” would be built:10
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.
A separate QI article about Clarke’s remark is available here.
In conclusion, QI believes that Arthur Kantrowitz deserves credit for this expression based on the testimony of Gerard K. O’Neill in “The CoEvolution Quarterly” of September 1975. During subsequent years instances of the saying were used by Timothy Leary, Arthur C. Clarke, and others.
Image Notes: Public domain illustration of an O’Neill cylinder space habitat from NASA/Rick Guidice. The image has been cropped and resized.
Acknowledgement: Great thanks to astrophysicist Jason T. Wright whose inquiry about the quotation attributed to Arthur C. Clarke led QI to formulate this question and perform this exploration. Wright obtained scans of the important article in “Advances in Earth Oriented Applications of Space Technology”.
- Website: National Academy of Engineering, Article title: Biographical sketch of Arthur R. Kantrowitz 1913-2008, Article author: Francis E. Kennedy (Submitted be the NAE Home Secretary), Date on webpage: undated, Website description: National Academy of Engineering (NAE) was founded in 1964; NAE is a nonprofit institution with offices in Washington, DC that provides engineering advice. (Accessed nae.edu on April 19, 2025) link ↩︎
- 1975 Fall (September 23, 1975), The CoEvolution Quarterly, Issue 7, Is the surface of a planet really the right place for an expanding technological civilization, Interview of Gerard K. O’Neill conducted by Stewart Brand, Start Page 20, Quote Page 25, Published by POINT, Sausalito, California. (Verified with scans) ↩︎
- 1977, Space Colonies, Edited by Stewart Brand, Chapter: Is the surface of a planet really the right place for an expanding technological civilization, Interview of Gerard K. O’Neill conducted by Stewart Brand, Start Page 22, Quote Page 27, A CoEvolutionBook of the Whole Earth Catalog, Published by POINT, Sausalito, California. Distributed by Penguin Books, New York. (Verified with scans) ↩︎
- 1977 January 30, Los Angeles Times, Timothy Leary: Messenger of Evolution, Section V: View, Start Page 1, Quote Page 18, Column 3, Los Angeles, California. (ProQuest) ↩︎
- 1977 May 24, The Globe and Mail, Section: Editorial, In a green cheese mine, Quote Page 6, Column 5 and 6, Toronto, Ontario, Canada. (ProQuest) ↩︎
- 1977 May 30, The Globe and Mail, Section: Letters to the Editor, Letter title: Solar power, Letter from: John Burghardt of Toronto, Quote Page 6, Column 1 and 2, Toronto, Ontario, Canada. (ProQuest) ↩︎
- 1978 June 22, Coventry Evening Telegraph, Last night’s television by Roger Harrabin, Quote Page 3, Column 4, Coventry, West Midlands, England. (Newspapers_com) ↩︎
- 1978 June 29, The Listener, Volume 99, Number 2566, Television: Surprise, surprise by Joseph Hone, (Review of television program Spaceships of the Mind BBC2), Start Page 843, Quote Page 844, Published by The BBC, London. (Verified with scans) ↩︎
- 1978, Spaceships of the Mind by Nigel Calder, Chapter 1: On Big Ideas, Quote Page 8, Column 2, The Viking Press, New York. (Verified with scans) ↩︎
- 1981, Advances in Earth Oriented Applications of Space Technology: An International Journal, Volume 1, Number 1, The Space Elevator: ‘Thought Experiment’, or Key to the Universe? by Arthur C. Clarke, (Note: Address to the XXXth International Astronautical Congress, Munich, 20 September 1979), Start Page 39, and Quote Page 47, Column 1, Pergamon Press Inc., Elmsford, Oxford, England. (Verified with scans) ↩︎