E.T., Phone Here

In the early spring months of 1950, the city of New York witnessed an outbreak of juvenile delinquency. Late at night, prowling gangs were stealing those iconic Department of Sanitation iron-mesh trash cans from New York’s street corners”and local newspapers at the time were in a dither.

That was also the time when America was going through one of its many flying-saucer crazes, a mania that would in that same decade bequeath to pop culture the delightfully cheesy sci-fi movie The Day the Earth Stood Still and the equally cheese-laden TV hit The Twilight Zone .

The coincidence of these two “leading cultural indicators” prompted the always whimsical New Yorker to publish a captionless cartoon by Alan Dunn in its 20 May 1950 issue, which showed a flotilla of flying saucers bivouacked on the Great Lawn of Manhattan’s Central Park: in the foreground could be seen aliens schlepping up DSNY trash cans into the cargo holds of their spaceships.

While all this was going on, the famous Italian-American physicist Enrico Fermi was working away at the famous government laboratory in Los Alamos, New Mexico. One day, he was chatting to Edward Teller and Herbert York as they walked over to a cafeteria for lunch, where they were joined by Leo Szilard, Eugene Wigner, and John von Neumann (all except Fermi and York were Hungarian émigrés).

Their topic was the recent spate of UFO sightings. (Roswell, site of perhaps the most famous claim of alien-visitation, was after all in the same state.) At that point another colleague, Emil Konopinksi, joined the group and told his fellows of the Dunn cartoon. Fermi drolly remarked that Dunn’s was a reasonable theory because it accounted for two distinct phenomena: the disappearance of trash cans and those recent reports of flying saucers. Just what scientists are supposed to do!

When the men sat down to lunch, discussion turned to other topics. Then, in the middle of the conversation and seemingly out of nowhere, Fermi asked: “Where is everybody?” Thus was born what has become known ever since then as Fermi’s Paradox.

Orbiting a middling star nestled among a teeming flock of other suns in our galaxy, which is itself one galaxy among billions of others, the earth must be one of countless planets just like it, so obviously we are not alone. But if there are so many ETs out there, then, as Fermi asked, where is everybody?

Fermi’s is a genuine paradox, because the same principle that is invoked by others to say that intelligent aliens are out there he used to refute the assertion. That principle is called the Copernican Principle or, perhaps more helpfully, the Principle of Mediocrity, which in colloquial terms means “We ain’t that special, so get over it.”

If we suppose”as the Mediocrity Principle tells us we must”that we have appeared somewhere in the middle of countless other episodes of intelligent beings emerging from their countless earth-like planets, then these earlier aliens must already have evolved far beyond our own pathetically primitive civilization. So they should already have arrived, and a long time ago too”just to show off their fancy new hotrod spaceships, if for no other reason. We would. But they haven’t. A paradox.

There are of course ways of short-circuiting this paradox, the subject of a most amusing book by the physicist Stephen Webb”whose amusement starts with its lengthy title: If the Universe is Teeming with Aliens, Where is Everybody? Fifty Solutions to the Fermi Paradox and the Problem of Extraterrestrial Life .

There are three basic options for answering Fermi: either aliens have already been here (Hollywood’s preferred solution); or they exist yet have chosen, for whatever reason, not to communicate with us (which is possible, but runs afoul of Ockham’s razor); or they don’t exist (Fermi’s solution).

Actually, solution #1 was already mooted that day at lunch when Fermi first enunciated his paradox. Szilard said, no doubt with a twinkle in his eye: “They are among us, and they call themselves Hungarians,” presumably a droll reference to the Hungarians’ remarkable intelligence.

And of course all those people who claim that the pyramids in Egypt were built by visitors from outer space, or that they themselves have been abducted by aliens, or actually saw flying saucers landing on their patios right next to papa’s home-built barbecue pit, have resolved the paradox to their satisfaction. Don’t believe them? Well, just check out the photographs taken on their iPhones and posted on their Facebook pages! (Skeptics might refer to unidentified flying objects, but they’re not at all unidentified to the folks who laps up supermarket tabloids.)

Webb has no trouble dispatching these reports of UFOs (and takes Hungarian chauvinism in stride too). The big problem with option #1”and it is a big, big problem”is the “slowness” of the speed of light.

Now the speed of light might seem pretty fast to us. But when judged against the vast distances in the universe, it plods along like a Sunday stroller out to take in the sights. It takes a full four years for the light coming from earth’s nearest star to get here, and billions of years for light from distant galaxies to get here. On earth, down in this woe-begotten vale of tears, even Indian smoke signals get better results.

Moreover, photons are able to travel at the speed of light only because they’re massless . Something as heavy as a spaceship laden with supplies for a long journey would take prodigious amounts of energy, and even then it would arrive at many of the Milky Way destinations we’d like to visit in about the same amount of time it took the human species to evolve from its last hominid ancestors about 200,000 years ago. And as for intergalactic travel, forget about it.

But since radio waves also travel at the speed of light, surely we should have picked up by now signals from the exo-versions of I Love Lucy and The Ed Sullivan Show . But so far, nothing has been picked up”despite numerous toilsome efforts of those dedicated drones who check their computers and radio telescopes every night at the Search for Extraterrestrial Intelligence (SETI) project. No ET seems to be phoning here.

So maybe the third solution is the only one left. Certainly we’d have to conclude we are truly alone if evolution on earth is as contingent as some evolutionary biologists say it is. For example, the late Steven Jay Gould claimed that if we rewound the “tape of evolution,” it would be extremely unlikely that humans would emerge again. Daniel Dennett retorts in Darwin’s Dangerous Idea that in that case SETI would make as much sense as the search for extraterrestrial kangaroos.

But even if the emergence of intelligent humans is quasi-inevitable, that still doesn’t mean that the Mediocrity Principles now kicks in. Perhaps the features of our solar system make earth unique as a home fit for life. Such is the argument of Simon Conway Morris’s book, whose subtitle gives away the thesis: Life’s Solution: Inevitable Humans in a Lonely Universe .

Conway Morris teaches both evolutionary biology and earth sciences at Cambridge University, which gives him a double expertise in this debate. (He is also a practicing Christian and gives Richard Dawkins a scorching blast of well-deserved criticism in his book).

According to him (and numerous others cited by Webb), Jupiter’s position and size are crucial, enabling it to serve as a kind of deflector shield to keep most asteroids and comets from hammering away at earth on a regular basis. Moreover, the moon had to come into being with only this mass and this orbit in order to stabilize earth’s own rotation around its current tilted axis, which of course has to be tilted “just so” to allow the right weather fluctuations to permit life. And how likely is that to be replicated elsewhere? these authors rhetorically ask.

Webb concludes his book”after covering far more options than I have outlined here”by insisting that we are indeed alone. Myself, I’m rather agnostic on the debate and can identify with W. H. Auden’s chipper cleric in his poem “Letter to Lord Byron”:

At least my modern pieces shall be cheery
Like English bishops on the Quantum Theory.