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.


{ 8 comments… read them below or add one }

Charles Ivie July 19, 2017 at 1:12 pm

At JPL I worked on Pioneer as well as Ranger, Surveyor, Mariner Mars and Venus. Those were exciting times.
A. C. Clark had a set of “laws” and my favorite was “Any sufficiently advanced technology will be indistinguishable from magic.” If you think of the advances in the last hundred or so years it is understandable. Imagine what a DaVinci or a Newton would think if they could be brought into today’s world and witnessed a 747 taking off from Heathrow or television or a traffic jam on one of California’s freeways.

While at Caltech and JPL I worked on a number of interesting projects but one of the most exciting was advanced mission studies where we looked at interstellar mission requirements and objectives. I coauthored a couple of papers on the subject which you may find interesting. There is a link to one of them below.

Also while working as a radio astronomer, which I did for several years, I got involved with SETI and I still run their “SETI at Home” project on several of my computers. While I think that SETI is a worthwhile project I suspect that it is overly optimistic when it comes to detecting ET. If we are lucky we will see evidence of “incidental” emission or maybe a large space structure like that proposed for “Tabbys Star” But, if they are talking to each other I suspect they will use something far more sophisticated than radio.

I met Carl Sagan when we convinced him to chair a series of conferences on the applications of artificial intelligence to the space program. Interesting guy. Our study leader, Dr. Ewald Heer became a character in his book “Contact”.


Charles Ivie July 19, 2017 at 6:45 pm
Nicholas Mee July 19, 2017 at 7:11 pm

I’m very sceptical about Tabby’s star. I’m sure it will turn out to have a natural explanation.


Charles Ivie July 19, 2017 at 8:11 pm

I suspect you are correct. We thought the same about pulsars until we figured out what they really were.


Charles Ivie July 19, 2017 at 8:13 pm

However, Tabby’s star is likely to turn out to be something very interesting even if it isn’t ET.


Paul Horth July 21, 2017 at 8:07 pm

I understand the argument presented, that there has been plenty of time (10 billion years?) for life elsewhere in the galaxy to form, to develop technology and then, in a geologically insignificant period of time, sweep across the galaxy in a wave of exploration. We see no sign of this. I would suggest though, that in some cases, such as here, life got started a little later. Since the number of planets is “astronomical”, maybe enough of them had a late start and are at a stage of development similar to ourselves or a liitle further, and this cohort has not yet followed the earlier ones into full blown exploration, followed by oblivion or something else. It is these galactic contemporaries, not the early starters, which we could hope to detect in some way that we could comprehend.
I would be interested in any comments .
Paul Horth


Nicholas Mee July 21, 2017 at 8:36 pm

Dear Paul
As you say, it’s certainly possible that alien civilizations have evolved elsewhere almost simultaneously with our own and they may be just ahead or just behind us, and this would explain why we are not aware of them.

However, I think Fermi’s argument is essentially probabilistic. It could be quantified, roughly, as follows. We know of no reason why an alien civilization could not have arisen somewhere in the galaxy at some time in the last billion years. If we assume it takes, say, 10 million years to colonize the entire galaxy, then there is only a 1% chance that our civilization has arisen during the period when the first alien civilization is colonizing the galaxy. Of course, there is a lot of guess work going on here, but this is the argument.

Perhaps we are lucky and we have evolved before the aliens have arrived or perhaps the evolution of an advanced civilization is an outrageous fluke that has only happened once in our galaxy.


Carl Larsen July 27, 2017 at 7:21 pm

I concur with all the comments foregoing, and it outlines clearly that the thought processes engaged in formulating a hypothesis about the possibility of Alien life is an extreme possibility, ignoring the religious explanation for mankind and his uniqueness, because of the infinitely huge distances, and the timing of the formulation of life, and the demise of the same will have, maybe, taken place many times with no crossover or collision with other intelligent life elsewhere. it may have, and maybe will happen again and again, all in different timeframes, without ever witnessing the presence of the other; a bit like the domino effect…they happen, but always before and after any other and never simultaneously. The only proof will be remnants of structures on the exoplanets, should we ever be able to visit them. So far, nothing has been discovered.


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