Where have all the ETs gone?

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At Los Alamos National Laboratory in the summer of 1950, four physicists sat down to lunch. One was Nobel laureate Enrico Fermi, a scientific genius arguably on a par with Albert Einstein. UFOs were in the news, and the four men briefly chatted about interstellar travel and aliens. Three of them moved on to other subjects, but as Prof. Adam Frank noted in his book "Light of the Stars," Fermi continued to ruminate and then blurted, "But where are they?"

That is, if extraterrestrial technologically advanced life existed, why hadn't we encountered it? Given the age of the universe (13.7 billion years), the stunning number of stars (and now we know for sure, planets), and the assumption that the evolution of life is not a special case on Earth, the cosmos should be teeming with life.

Fermi's cut-to-the-chase question became known as "Fermi's Paradox." Adam Frank's version: "If technologically advanced exo-civilizations are common, then we should already have evidence of their existence either through direct or indirect means."

After all, our solar system is only four billion years old — one-third the age of the universe — and we exist. Countless star/planet systems preceded us by billions of years, and how many of them produced life? Our Milky Way galaxy has over 100 billion stars, and based on the current detection rate is probably home to a trillion planets or more. And there are billions of other galaxies. Opportunity for the development of life and intelligence is profound. But we haven't encountered exo-civilizations.

Four decades ago, astrophysicist Michael Hart calculated the likelihood of galactic colonization, and Adam Frank summarized the result in his book: "Assuming an exo-civilization appeared that built ships capable at traveling ten percent of the speed of light, Hart showed that within just 650,000 years [a mere fraction of the age of the cosmos] these creature would cross the width of the galaxy … radiating outward from their home world, and quickly colonize every star system."

Some are convinced we have indeed been visited by ETs, but there's no credible evidence. Personally, I'd be thrilled to have proof of an advanced technological society from outside our solar system. It would indicate that all such societies do not self-destruct and there might be hope for us. Why? Because one answer to Fermi's question is that between weapons of mass destruction and ecological catastrophe, both of which may be a universal byproduct of technology, no advanced civilization survives past a certain threshold. It's an evolutionary experiment with a strong, if not certain, likelihood of failure, and a path we earthlings are treading.

A more benign (perhaps) answer to Fermi's question might be that interstellar travel is always extremely difficult and prohibitively expensive given the cosmic scale. Traveling at the speed of light (186,000 miles per second) it would take four years to reach the nearest star, and so far as we know you can't travel that fast anyway. Granting Micheal Hart's speculative velocity of 10% light speed, 40 years would be required. But for organic life-forms, long duration spaceflight may be impossible.

For example, despite the hype, we've yet to solve the problems of transporting a few humans to Mars, which is just around the corner. Given the intensity of lethal cosmic radiation and the length of the journey, a trip to Mars at this point is essentially a suicide mission. No doubt you could still find people willing to go, but what's the point? If it's knowledge you want, our robot space probes have been doing a superb job. Machine missions to Mars and Venus, for example, have significantly contributed to our understanding of the Earth, particularly our atmosphere and the mechanics of climate change. The machines are relatively inexpensive and don't require complex and costly life support infrastructure.

It's a pipe dream of arrogant billionaires to think we can save human civilization by colonizing Mars with actual people in the near future. Sorry boys, but we need to focus (and spend) on the less glamorous needs of earthlings and our home planet now.

Additionally, reliable reports from military pilots have indicated unidentified anomalous phenomena (UAPs) performing ultraviolent maneuvers at high velocities that are impossible for any existing aircraft technology. If they are indeed spaceships, it's probable no biological being could survive aboard them, and they are at best alien machines. During the recent congressional hearings on UAPs, a retired Air Force officer claimed the federal government was hiding the remains of biological aliens. This seems highly unlikely. Extraordinary claims — as they say — require extraordinary evidence, and such was not presented.

The subset of unexplained UAP reports could also be natural phenomena we don't yet understand. Recall that total solar eclipses, which can now be explained and diagramed by an intelligent grade-schooler, were once considered divine events. It's well that the government is sharing data on UAPs, and while that's no sure antidote to conspiracy theories, the airing of uncertainty is healthy. But I believe biological aliens are one of the least likely explanations.

Nevertheless, that seems the most popular default position regarding UFOs/UAP. Science fiction stories play a role, with aliens often portrayed as either monsters or saviors, to either destroy us or guide us, instilling terror or hope. There's a distinctly religious tone to some portrayals of alien contact, and they do reside in "heaven." Religious movements have been created around the notion of space-faring alien civilizations.

Some readers may recall the sensational news from March 1997 when 39 members of the Heaven's Gate cult committed mass suicide in California. They espoused a blend of Biblical prophecy and "ufology" and were convinced that an alien spacecraft was following Comet Hale-Bopp as it entered the inner solar system. Members believed that after death their mind/soul would be transferred to the craft and they would become immortal extraterrestrial beings. Though Heaven's Gate is an extreme example, many believers have equated aliens with angels, or supported other mash-ups of theology and astrobiology.

Though it's certainly not illogical to assume we are alone in the cosmos (there is no proof yet that we are not), for many it's an uncomfortable — even disturbing — thought, hence the fantasies and speculations. It also smacks of hubris. Yet Fermi's question remains: Where are they? If only intelligent machines accomplish extended space travel, perhaps there'll be no contact until our brand of AI is independently venturing out from the Earth and we carbon-based "biologicals" have served our purpose — evolving just enough to create the silicon-based "digitals" that will own the future, and will have no reason to pay attention to us.

"Where are they?" Maybe they are all exactly where they started from and no further, or maybe they are already extinct on their planets. This is, I know, a highly speculative cautionary tale, but what seems clear is that for the foreseeable future we have only one world on which to live, and if we don't care for it and for each other, ETs — in any guise — are irrelevant.

Peter M. Leschak, of Side Lake, Minn., is the author of "Ghosts of the Fireground" and other books.