What Is the Fermi Paradox?

In the summer of 1950, four physicists walked to lunch at Los Alamos talking about a wave of flying saucer reports and a New Yorker cartoon that blamed aliens for New York’s missing trash cans. Over the meal, Enrico Fermi asked some version of “Where is everybody?” Herbert York later recalled that Fermi then ran the numbers and concluded that Earth should have been visited long ago, and many times over.

Eleven years later, the astronomer Frank Drake turned the question into an equation. It multiplies seven factors, from how fast the galaxy makes stars to how long a civilization stays detectable, to estimate how many civilizations we might hear from. Astronomy has since filled in the first terms: more than 6,000 planets beyond our solar system are now confirmed, and roughly one Sun-like star in five may host an Earth-size planet in the zone where liquid water is possible. The biological and social terms are still unknown.

Scientists have offered dozens of answers. Life may be rare, or we may be early. Civilizations may not last, or we may simply not have looked hard enough. One answer was set aside at the start by assumption: that someone is already here. The most influential version of the argument rests on the premise that “there are no intelligent beings from outer space on Earth now.” That premise is exactly what the UAP disclosure debate puts to the test.

Sources: Eric M. Jones, “Where Is Everybody?” An Account of Fermi’s Question, Los Alamos National Laboratory (1985) · Michael H. Hart, Quarterly Journal of the Royal Astronomical Society (1975) · NASA Exoplanet Archive · Petigura, Howard and Marcy, PNAS (2013)

A Question Asked Over Lunch

The paradox carries Fermi’s name, but he never wrote it down, and the men at the table did not remember it the same way.

The best record of the lunch comes from Eric Jones, a Los Alamos scientist who wrote to the three surviving guests in 1984 and 1985: Emil Konopinski, Edward Teller and Herbert York. All three remembered Fermi’s question. Teller recalled it as “Where is everybody?” York remembered “Don’t you ever wonder where everybody is?”

Teller also remembered Fermi asking how likely it was that, within ten years, we would see clear evidence of a material object moving faster than light. Teller guessed one in a million. Fermi said one in ten was closer.

The astronomer Robert Gray has argued that Fermi was mostly doubting interstellar travel, not doubting that life exists elsewhere. The formal argument that “they are not here, so they do not exist” was published by Michael Hart in 1975 and extended by Frank Tipler in 1981. The phrase “Fermi paradox” did not appear in print until 1977.

Sources: Jones (1985) · Robert H. Gray, “The Fermi Paradox Is Neither Fermi’s Nor a Paradox,” Astrobiology (2015) · Hart (1975) · Frank J. Tipler, “Extraterrestrial Intelligent Beings Do Not Exist,” Physics Today (1981)

The Drake Equation

Frank Drake wrote his equation as an agenda for a meeting, not as a way to get an answer. It is still the best map of what we know and what we don’t.

In 1961, Drake hosted ten scientists at the National Radio Astronomy Observatory in Green Bank, West Virginia, for the first meeting on searching for extraterrestrial intelligence. Carl Sagan, Philip Morrison and Otto Struve were among them. To organize the discussion, Drake wrote:

N = R* × fp × ne × fl × fi × fc × L

• R*: how many stars the Milky Way forms each year
• fp: the fraction of those stars with planets
• ne: how many planets per system could support life
• fl: the fraction of those planets where life actually begins
• fi: the fraction of those where intelligence evolves
• fc: the fraction of those that produce signals we could detect
• L: how long such a civilization keeps sending them

The group concluded that the answer depends mostly on L, and estimated somewhere between 1,000 and 100 million civilizations in our galaxy.

Sixty-five years on, the first three terms are largely measured. Nearly every star appears to have planets, and Kepler data suggested that about 22 percent of Sun-like stars have an Earth-size planet in the habitable zone. The last four terms are still guesses.

Two studies show how far apart the guesses can land. In 2016, Adam Frank and Woodruff Sullivan asked how unlikely a technological species would have to be for us to be the only one. Their answer: less than about one chance in 10 billion trillion per habitable planet across the universe. In 2018, Anders Sandberg, Eric Drexler and Toby Ord went the other way. Once the real uncertainty in each term is taken into account, they found, it is quite possible that we are alone.

Sources: Petigura, Howard and Marcy, “Prevalence of Earth-size planets orbiting Sun-like stars,” PNAS (2013) · A. Frank and W.T. Sullivan, Astrobiology (2016) · Sandberg, Drexler and Ord, “Dissolving the Fermi Paradox” (2018)

The Proposed Answers

Most answers fall into a few families. Each one changes what we should expect to find, and where.

We are rare. Something makes the step from chemistry to civilization extremely hard. The economist Robin Hanson called this the Great Filter (1996). If the filter is behind us, we are lucky. If it is ahead, it is a warning.

We are early. The conditions for complex life may only recently have become common, so we could be among the first.

Civilizations don’t last. If technological societies destroy themselves or fade quickly, L is small and few overlap with us in time.

We haven’t looked. A 2018 study by Jason Wright and colleagues estimated that the radio search for intelligence so far is comparable to checking a large hot tub’s worth of water for fish in all of Earth’s oceans.

They are staying out. The “zoo hypothesis,” proposed by John Ball in 1973, suggests that advanced civilizations may deliberately leave a young one alone.

They are here. Hart listed this possibility in 1975 and rejected it. His argument starts from what he called “Fact A”: “There are no intelligent beings from outer space on Earth now.”

Sources: Robin Hanson, “The Great Filter” (1996) · Wright, Kanodia and Lubar, “How Much SETI Has Been Done?” Astronomical Journal (2018) · John A. Ball, “The Zoo Hypothesis,” Icarus (1973) · Hart (1975)

Where the Paradox Meets Disclosure

The Fermi paradox is only a paradox if Fact A is true. For the first time, that premise is being tested in public.

Since 2017, the U.S. government has acknowledged that military personnel regularly encounter objects they cannot identify. In July 2023, a former intelligence officer, David Grusch, told a House subcommittee under oath that the government has run a decades-long program to recover craft of non-human origin. The Pentagon’s All-domain Anomaly Resolution Office said in 2024 that it found no evidence to support such claims. Scientists have started looking too: Harvard’s Galileo Project, launched in 2021, searches the sky near Earth for objects that might be technology from elsewhere.

None of this settles the question. But it changes how the question should be asked. If even one of those accounts proves true, Fermi’s “Where is everybody?” becomes a different question: why weren’t we told? That is the question the New Paradigm Institute was founded to answer, through law, through the record, and by preparing the public for what the answer may mean.

Sources: House Oversight subcommittee hearing, July 26, 2023 · AARO, Report on the Historical Record of U.S. Government Involvement with UAP, Vol. 1 (2024) · The Galileo Project, Harvard University

Related

• What Is the Kardashev Scale? · Core Learning Tool
• Could Disclosure Re-Enchant the Universe? · Full Disclosure, episode 18
• The UAP Disclosure Timeline · Core Learning Tool
• What Did David Grusch Tell Joe Rogan? · Full Disclosure, episode 15