About Drake equation
The Drake equation is a probabilistic argument written by radio astronomer Frank Drake in 1961 to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way. Because several of its terms rely on pure conjecture, the formula cannot support firm conclusions and yields results ranging from less than one civilization to tens of millions. Its primary value is setting out what scientists need to know and serving as an agenda for discussion.
The full story, section by section
The story of Drake equation in 6 parts. Tap any part to read it in full.
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The equationIn the form first published in Drake's 1965 paper, the equation is N = R∗ · fp · ne · fl · fi · fc · L, where N is the number of civilisations in the galaxy with which communication might be possible, and:Read this part →
image shows drake equation in higher quality . drake equation is used to estimate chances of finding life on other planets. · Photo: Mohammad Alrohmany, CC BY-SA 3.0, Wikimedia Commons -
HistoryIn September 1959 the physicists Giuseppe Cocconi and Philip Morrison argued in Nature that radio telescopes were now sensitive enough to detect transmissions from other civilisations.Read this part →
The Green Bank Telescope at the National Radio Astronomy Observatory, Green Bank, West Virginia, where Drake ran Project Ozma and the 1961 meeting · Photo: Jarek Tuszyński, CC BY-SA 3.0, Wikimedia Commons -
EstimatesThe group's "educated guesses" were:Read this part →
Adam Frank explains which terms in the Drake equation were recently estimated at the Rochester Academy of Science Annual Spring Lecture 2024 at the RIT Carlson Center for Imaging Science, Room 1125. The lecture was entitled "A Little Talk About Alien… · Photo: DanielPenfield, CC BY-SA 4.0, Wikimedia Commons -
Criticism and modificationsCritics note that, apart from star formation and planets, the terms rest on conjecture about life, intelligence and civilisation, where we have only one example.Read this part →
Dr. Drake, revisiting the variables of the Drake Equation, several decades after its inception. · Photo: Raphael Perrino, CC BY 2.0, Wikimedia Commons -
The Fermi paradoxA long-lived civilisation could spread across the galaxy even at slow speeds, yet no confirmed sign of alien life has been found, hence Enrico Fermi's question "Where is everybody?" In Drake-equation terms the proposed answers fall into th…Read this part → Illustration drawn for this site — not a photograph.
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In popular cultureGene Roddenberry cited the equation in support of the many inhabited worlds of Star Trek.Read this part → Illustration drawn for this site — not a photograph.
Key people
The people at the centre of the story — witnesses, investigators, officials and sceptics:
- John C. LillyJohn C. Lilly was an American physician, neuroscientist, and writer who invented the sensory-deprivation tank in 1954 and became famous for his attempts to communicate with dolphins. Later in life, t…
- Carl SaganCarl Edward Sagan was an American astronomer, planetary scientist, and science communicator who lived from 1934 to 1996. He played a major role in space missions, discovered Venus's high surface temp…
Programs, organizations & documents
The official programs, groups and papers involved:
🏛️ Program or study · 2 min readSETIThe Search for Extraterrestrial Intelligence: listening for signals from civilisations on other worlds.
🏢 Organization · 10 min readBAASSBigelow Aerospace Advanced Space Studies (BAASS) was a company formed in 2008 by businessman Robert Bigelow to carry out the Pentagon-funded Advanced Aerospace Weapon System Applications Program (AAWSAP). Over roughly two years, the company collected UFO repo…Related topics & places
Ideas, terms and places that come up in the story:
📖 Term · 5 min readFermi paradoxThe Fermi paradox is the contradiction between the high probability that extraterrestrial civilizations exist and the lack of any clear evidence for them. The term originated from a 1950 lunchtime conversation in Los Alamos involving physicist Enrico Fermi, w…
🧭 Topic overview · 2 min readAre aliens real?What science and the official investigations say about whether extraterrestrial life exists and whether it has visited Earth.🏛️ Official records
- AAWSAP DIRD, An Introduction to the Statistical Drake Equation, March 2010Department of War · 2010-03-11This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIR…
🛸 UFO sightings about Drake equation
Sightings that mention Drake equation
More in the encyclopedia
Other articles that link to or mention Drake equation:
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- Ultraterrestrial hypothesisThe ultraterrestrial hypothesis is the idea that UFOs and their occupants originate from other dimensions or realities coexisting with Earth rather than from other planets. Writer John Keel coined th…
- Ancient astronautsAncient astronauts is a set of pseudoscientific beliefs holding that intelligent extraterrestrials visited Earth in prehistoric or ancient times to shape human cultures, technologies, and religions. …
- TransmediumTransmedium describes objects that reportedly move between different environments like space, air, and water without difficulty. United States law includes transmedium devices as a category of uniden…
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- Nordic aliensNordic aliens are described in UFO literature as tall, human-like extraterrestrials with blond hair, blue eyes, and fair skin who are said to originate from the Pleiades star cluster. These benevolen…
Questions & answers
What is Drake equation?
Drake equation: The Drake equation is a probabilistic argument written by radio astronomer Frank Drake in 1961 to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way. Because several of its terms rely on pure conjecture, the formula cannot support firm conclusions and yields results ranging from less than one civilization to tens of millions. Its primary value is setting out what scientists need to know and serving as an agenda for discussion. Read: Drake equation →
Who is John C. Lilly?
John C. Lilly was an American physician, neuroscientist, and writer who invented the sensory-deprivation tank in 1954 and became famous for his attempts to communicate with dolphins. Later in life, through isolation tanks and psychedelics, he developed beliefs about cosmic entities and a hierarchy of controllers. Read: John C. Lilly →
Who is Carl Sagan?
Carl Sagan: Carl Edward Sagan was an American astronomer, planetary scientist, and science communicator who lived from 1934 to 1996. He played a major role in space missions, discovered Venus's high surface temperature, co-created interstellar messages, and co-wrote and presented the popular television series Cosmos. He also worked extensively to study UFO reports scientifically while remaining a prominent skeptic of the extraterrestrial hypothesis. Read: Carl Sagan →
What is SETI?
SETI: The Search for Extraterrestrial Intelligence: listening for signals from civilisations on other worlds. Read: SETI →
What is BAASS?
BAASS: Bigelow Aerospace Advanced Space Studies (BAASS) was a company formed in 2008 by businessman Robert Bigelow to carry out the Pentagon-funded Advanced Aerospace Weapon System Applications Program (AAWSAP). Over roughly two years, the company collected UFO reports, studied phenomena at Skinwalker Ranch, and commissioned technical papers on speculative aerospace subjects before its funding ended. Read: BAASS →
What is Fermi paradox?
Fermi paradox: The Fermi paradox is the contradiction between the high probability that extraterrestrial civilizations exist and the lack of any clear evidence for them. The term originated from a 1950 lunchtime conversation in Los Alamos involving physicist Enrico Fermi, who asked "Where is everybody?" Proposed explanations range from life being extremely rare and civilizations dying out quickly to aliens choosing to stay hidden, while decades of searches have found no clear signs of extraterrestrial life. Read: Fermi paradox →
What is Are aliens real??
Are aliens real?: What science and the official investigations say about whether extraterrestrial life exists and whether it has visited Earth. Read: Are aliens real? →