Where Is Everybody?

by Nicholas Mee on July 14, 2017

Enrico Fermi

Enrico Fermi was born in Rome in 1901. He was one of the great physicists of the 20th century and made many important contributions to physics including a ground breaking theory of the weak nuclear force that predicted the existence of neutrinos. He was also a leading experimental physicist and created the first nuclear reactor under the sports fields at the University of Chicago in December 1942. The artificial element number 100 fermium is named in his honour.

One day while working at the nuclear research centre at Los Alamos in 1950 Fermi strolled to lunch with his colleagues Emil Konopinski, Edward Teller and Herbert York. Press speculation about alien spacecraft was rife at the time and the conversation turned to recent reports of UFO sightings and a newspaper cartoon blaming aliens for the theft of municipal rubbish bins. Later, during lunch Fermi suddenly exclaimed: ‘Where Is Everybody?’. Teller recalled long afterwards that this was met with roars of laughter. Everyone knew what Fermi meant, but his startling question seemed to come from nowhere. Fermi followed up his lunchtime observation with a series of calculations estimating the probability that technologically advanced civilizations would arise and concluded that we ought to have been visited long ago and many times over. The lack of evidence for such visitations has become known as the Fermi paradox.

The aliens and the municipal trashcans. Drawing by Alan Dunn (c) 1950, 1978. The New Yorker Magazine Inc.

The Fermi Paradox

Crude inferences based on the vast number of stars in our galaxy might suggest that plenty of intelligent lifeforms must be out there somewhere. But according to Fermi this might not be the case. His argument boils down to the following observations. The first stars in the galaxy appeared soon after the Big Bang 13.8 billion years ago. There would have been a long time lag in setting the stage for the arrival of sentient beings. Billions of years would pass while carbon, nitrogen, oxygen and the other elements of life accumulated in quantities sufficient for life-bearing planets to arise. But the Earth is a mere 4.57 billion years old and it has taken all of this 4.57 billion years for a technological civilization to evolve. Many stars are older than the sun and the evolution of intelligence on Earth was a long and slow process. There is every reason to suppose therefore that intelligent life could have appeared on other worlds long before ours. If the conditions for the evolution of intelligent life are prevalent throughout the galaxy, then we should expect that technological civilizations have arisen millions if not billions of years ago.

The Milky Way as seen from northern Chile. Credit & Copyright: Serge Brunier

It is just 5,500 years since the earliest writing in Ancient Sumeria and Egypt, 400 years since the first telescope, 120 years since the first radio communications and 30 years since the dawn of the World Wide Web. The whole of human technology has arisen within a brief few thousand years, so we must expect the technology of any ancient alien civilization to have long surpassed our own. Nevertheless, we are already contemplating the possibility of sending nanoprobes to the stars, as proposed in Breakthrough Starshot. (For more about Breakthrough Starshot see the post: To Boldly Go… .) It is only natural that other civilizations are equally curious and have similar desires to explore the stars. But we can barely imagine the capabilities of a civilization 1000 years in advance of our own, never mind one a million years in advance. It seems reasonable to suppose that such a civilization would have developed fleets of robotic probes that could colonise planets in distant star systems and utilise the resources of those planets to build new fleets of robotic probes that could seek out new star systems to explore and colonise.

The diameter of our galaxy is around 100,000 light years. At one fifth of the speed of light, the speed envisaged by Breakthrough Starshot, it would take no more than half a million years to cross the entire galaxy. There is no reason why, in principle, fleets of self-replicating robotic probes could not colonise the entire galaxy within one or at most a few million years, and, as Fermi pointed out, if the galaxy really does harbour technological civilizations, then they should have been around for much longer than this. So the colonisation of the galaxy should already have happened. So, as Fermi said: ‘Where Is Everybody?’


The first hydrogen bomb test, code-named Ivy Mike.

A number of answers have been put forward to explain the Fermi paradox. One disheartening possibility is that technological civilizations do frequently arise, but they are short-lived as their technology inevitably leads to self-destruction and the rapid demise of the civilization. This was a concern of the delegates who met to discuss the search for extraterrestrial intelligence (SETI) at Green Bank observatory in 1961. (SETI is discussed in the post: Somewhere Over the Rainbow.) This was at the height of the Cold War, less than a year before the Cuban Missile Crisis which threatened humanity with a return to the Stone Age and possibly even total annihilation. The threat of nuclear holocaust may have receded somewhat, but we now have global warming and ecological degradation to contend with. Who knows whether we will survive long enough to colonise the galaxy.

The Zoo Hypothesis

For the more optimistic there are other explanations such as the possibility that they are here, but we haven’t noticed! Perhaps we have been visited by stealth nanobots, but the extraterrestrials choose not to disclose their presence. Explanations of this sort go by the name of the Zoo Hypothesis.

We Really Are the First!

Then there is the daunting possibility that there are no other alien civilizations and we really are the first technological civilization to evolve in the Milky Way galaxy. This startling proposition is sometimes known as the Rare Earth Hypothesis.

In the words of Sir Arthur C. Clarke:

‘Two possibilities exist: either we are alone in the universe or we are not.
Both are equally terrifying.’


Further Information

There is more information about Enrico Fermi and his pioneering work in nuclear physics in my book: Higgs Force: Cosmic Symmetry Shattered.


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