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In fiction, engineering, and thought experiments, unobtainium is a material ideal for a particular application but impractically hard to get. Unobtainium originally referred to materials that do not exist at all, but more recently, it has been used to describe real materials that are unavailable due to extreme rarity or cost. Less commonly, it can mean a device with desirable engineering properties for an application that are exceedingly difficult or impossible to achieve.

The properties of any particular example of unobtainium depend on the intended use (e.g., a pulley made of unobtainium might be massless and frictionless). But for a nuclear rocket, unobtainium might have the needed qualities of lightness, strength at high temperatures, and resistance to radiation damage: A combination of all three qualities is impossible with today's materials. The concept of unobtainium is often applied hand-wavingly, flippantly, or humorously.

The word "unobtainium" derives humorously from "unobtainable", with -ium, a suffix for chemical element names. It predates the similar-sounding systematic element names, such as ununennium. An alternate spelling, unobtanium, is sometimes used, perhaps based on the spelling of real elements like titanium and uranium.

Engineering origin[edit]

Since the late 1950s,[a][1] aerospace engineers have used the term "unobtainium" when referring to unusual or costly materials, or when theoretically considering a material perfect for their needs in all respects, except that it does not exist. By the 1990s, the term was in wide use, even in formal engineering papers such as "Towards unobtainium [new composite materials for space applications]."[2][3]

The word "unobtainium" may well have been coined in the aerospace industry to refer to materials capable of withstanding the extreme temperatures expected in re-entry.[1] Aerospace engineers are frequently tempted to design aircraft which require parts with strength or resilience beyond that of currently available materials.

Later, 'unobtainium' became an engineering term for practical materials that really exist, but are difficult to get.[4] For example, during the development of the SR-71 Blackbird spy plane, Lockheed engineers at the "Skunk Works" under Clarence "Kelly" Johnson used 'unobtainium' as a dysphemism for titanium. Titanium allowed a higher strength-to-weight ratio at the high temperatures the Blackbird would reach, but its availability was restricted because the Soviet Union controlled its supply.[b]

Contemporary popularization[edit]

By 2010, the term had diffused beyond engineering, and now can appear in the headlines of mainstream newspapers, especially to describe the commercially useful rare earth elements (particularly terbium, erbium, dysprosium, yttrium, and neodymium). These are essential to the performance of consumer electronics and green technology, but the projected demand for them so outstrips their current supply that they are called "unobtainiums" within the ore industry[5] and by commentators on the US Congressional hearings into the supply security of rare-earths.[6][7]

'Unobtainium' has come to be used as a synonym for "unobtainable" among people who are neither science fiction fans nor engineers to denote an object that actually exists, but which is very hard to obtain either because of high price (sometimes referred to as "unaffordium") or limited availability. It usually refers to a very high-end and desirable product. Examples are rear cassettes in the mountain biking community,[8] parts that are no longer available for old-car enthusiasts,[9][10] parts for reel-to-reel audio-tape recorders, and rare vacuum tubes such as the 1L6 or WD-11 that can now cost more than the equipment in which they were fitted.[11]

There have been repeated attempts to attribute the name to a real material. Space elevator research has long used "unobtainium" to describe a material with the necessary characteristics,[12][13] but carbon nanotubes might have these characteristics.[14] The eyewear and fashion wear company Oakley, Inc. also frequently denotes the material used for many of their eyeglass nosepieces and earpieces, which has the unusual property of increasing tackiness and thus grip when wet, as unobtanium.[15]

Science fiction[edit]

A piece of the valuable "unobtanium" from Avatar

It was first used in The Core in 2003,[16] and also used in James Cameron's 2009 movie Avatar, as a substance that was named "unobtanium". In the film, it is a room-temperature superconductor mined on the fictional moon Pandora that makes crewed interstellar space travel to the planet financially feasible.[17]

Similar terms[edit]

The term handwavium (suggesting handwaving) is another term for this hypothetical material, as are buzzwordium, impossibrium, raritanium, and hardtofindium.[citation needed]

The related term phlebotinum (a derisive term, drawn from phlebotomy) is used to describe a technological plot device created by a science fiction writer to "magically" advance the plot to a desired point.[18]

The term eludium (also spelled with variants such as illudium) has been used to describe a material which has "eluded" attempts to develop it. This was mentioned in several Looney Tunes cartoons, where Marvin the Martian tried (unsuccessfully) to use his "Eludium Q-36 Explosive Space Modulator" to blow up the Earth.[19]

Another largely synonymous term is wishalloy,[20] although the sense is often subtly different in that a wishalloy usually does not exist at all, whereas unobtainium may merely be unavailable.

A similar conceptual material in alchemy is the philosopher's stone, a mythical substance with the ability to turn lead into gold, or bestow immortality and youth. While the search to find such a substance was not successful, it did lead to discovery of a new element: phosphorus.[21]

See also[edit]


  1. ^ "unobtainium, n. A substance having the exact high test properties required for a piece of hardware or other item of use, but not obtainable either because it theoretically cannot exist or because technology is insufficiently advanced to produce it. Humorous or ironical." Listed in "Interim Glossary, Aero-Space Terms," as compiled by Woodford Heflin and published in February 1958 by the Air University of the US Air Force.
  2. ^ Relatively large amounts of titanium are used in aircraft such as the F-15, F-18, and F-22 fighters and the B-1 bomber.


  1. ^ a b Since at least the 1950s: Hansen, James R. (1987) "Engineer in Charge: A History of the Langley Aeronautical Laboratory, 1917–1958." The NASA History Series, sp-4305. Chapter 12, recounting an October 1957 meeting, mentions the problems caused by "the lack of a superior high-temperature material (which the Langley structures people dubbed 'unobtainium')" This paragraph in turn cites Becker, John V. "The Development of Winged Reentry Vehicles, 1952–1963," unpublished, dated 23 May 1983.
  2. ^ Misra, Mohan (Nov–Dec 1990). "Towards unobtainium [new composite materials for space applications]". Aerospace Composites and Materials. 2: 29–32. Archived from the original on 2009-04-24.
  3. ^ Dean, Edwin B. (1989). "Parametric cost analysis: a design function". American Association of Cost Engineers 33rd Annual Meeting. Vol. 25. p. 28. CiteSeerX
  4. ^ "Unobtainium". Metal Suppliers Online. Retrieved 2010-06-04. We can loosely define it as any metal that is specified by Engineering and unavailable to Purchasing
  5. ^ Jeremy Hsu (Sep 20, 2010). "Boeing launches search for crucial rare earth elements". NBC.
  6. ^ Hodge, Nathan (2010-03-16). "Congress Holds Hearings on Unobtainium". Retrieved 2010-06-04. The House Committee on Science and Technology’s investigations and oversight panel is holding a hearing today on rare-earth metal supplies, focusing on China’s near-monopoly on the stuff.
  7. ^ Kosich, Dorothy (2010-01-13). "The Rare Earth Revolution has investors stampeding". Mineweb. Archived from the original on 2014-02-01. Retrieved 2010-06-04. Metals analyst Christopher Ecclestone suggests the hunt for Unobtainium storyline reminds him 'of some of the talk surrounding Rare Earths (REE) these days'
  8. ^ Mat Brett (Jan 5, 2012). "Spin Unobtanium Monobloc Cassette".
  9. ^ Jay Ramey (Dec 10, 2019). "Hey, Lancia Delta Integrale owners, FCA found some unobtainium-level stuff you might be interested in". autoWeek.
  10. ^ Chris Petris, How to Restore Your Corvette, 1963-1967, p. 13, CarTech Inc, 2012 ISBN 193470976X.
  11. ^ Rob Squire (Jul 18, 2018). "On the Bench #65" (PDF). AudioTechnology.
  12. ^ Arnold, James R.; Thompson, William B. (1992). "Advanced propulsion for LEO-Moon transport: II. Tether configurations in the LEO-Moon system: The Role of "Unobtainium"". Nasa. Johnson Space Center, the Second Conference on Lunar Bases and Space Activities of the 21St Century, Volume 1. Lunar and Planetary Institute: 57. Bibcode:1992lbsa.conf...55A.
  13. ^ "Wanted: unobtainium Going Up? Private Group Begins Work on Space Elevator". Archived from the original on 2010-04-06. Retrieved 2010-05-19.
  14. ^ DAVID APPELL (Jun 14, 2017). "BUILDING AN ELEVATOR TO SPACE". Pacific Standard.
  15. ^ Graham Cottingham (Jun 21, 2019). "Oakley Cycling Sunglasses". Cycling News.
  16. ^ "The Core", Wikipedia, 2022-08-02, retrieved 2022-08-10
  17. ^ This property of Unobtanium is stated in movie guides, rather than in the film. Wilhelm, Maria; Dirk Mathison (November 2009). James Cameron's Avatar: A Confidential Report on the Biological and Social History of Pandora. HarperCollins. p. 4. ISBN 978-0-06-189675-0.
  18. ^ Lang, Anouk (October 2010). "'The Status is Not Quo!': Pursuing Resolution in Web-Disseminated Serial Narrative". Narrative. 18 (3): 367–381. doi:10.1353/nar.2010.0002. S2CID 162650104. ... Joss Whedon's work is such that there is an invented term—'phlebotinum'—which he and other writers employ when talking about devices they use to move the plot on which are incidental to the action.
  19. ^ Differences of opinion exist regarding the correct pronunciation; Chuck Jones rendered the modulator's name as Q-36 in print in Chuck Amuck : The Life and Times of an Animated Cartoonist (New York: Farrar Straus & Giroux, 1989; ISBN 0-374-12348-9), p. 213
  20. ^ Heppenheimer, Thomas A. (1999). "NASA SP-4221: The Space Shuttle Decision – NASA's Search for a Reusable Space Vehicle". Chapter 8
  21. ^ "Experts Warn of Impending Phosphorus Crisis", by Hilmar Schmundt, Spiegel, 21 April 2010

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