American Scientist

To the Editors:

I found Howard A. Smith’s article “Questioning Copernican Mediocrity” (July–August) interesting, especially the discussion of the radius within which we might reasonably hope to communicate with alien life forms. His article also reminded me why I’ve long thought that the last term in the Drake Equation, which famously estimates the number of intelligent extraterrestrial civilizations in our galaxy, is the most significant in understanding the Fermi Paradox.

Among the many factors in the equation that Frank Drake considered in 1961, the length of time that a technological civilization releases detectable signals into space now seems the weakest link. We have been releasing such radio signals for barely more than 100 years. It seems possible that within another 100 years there will be no one left on Earth sending such signals. Our exploding population, rapid exhaustion of the necessary resources to support a technological civilization, already visible destruction of a climate and environment that can sustain life on Earth, and threats of nuclear annihilation—all of these suggest that perhaps no technological civilization that evolves anywhere in the universe lasts long enough to broadcast its existence for a sufficient amount of time to be found by another short-lived technological civilization.

I presume that whatever direction evolution might take on other planets will be governed by the same principles that Charles Darwin discovered here on Earth. Like us, such planets’ intelligent species (if any) will find it difficult or even impossible to overcome their tendency to overpopulate and overexploit their ecological niche, ultimately leading to their rapid extinction or reduction to a pretechnological state of living. If there is intelligent life on other planets, it is most likely to be either preindustrial or post-technological. In either case, we wouldn’t be likely to find it.

If my speculations are true, Smith’s plea that we treat our special planet with more respect takes on even greater significance. We may indeed be alone, but in case we are not, perhaps we should try harder to last long enough to be found.

John Cushing
Evergreen State College (Emeritus)
Bend, Oregon

Dr. Smith responds:

I thank Dr. Cushing for his comments. I think that the most uncertain factors in the Drake Equation are the ones estimating the proportion of planets harboring conscious life, because we know the least about them. Regarding the lifetime of civilizations, however, Stephen Hawking famously echoes sentiments similar to Dr. Cushing’s when he speaks out against contacting aliens. He simplistically claims that because they will be much more advanced than we are and presumably will have also evolved through Darwinian processes, they will be, to his way of thinking, dangerously violent.

I am more hopeful than either Dr. Cushing or Hawking; after all, evolutionary biologists have pointed out that sentiments such as altruism and gratitude are also the products of evolution. My opinion is that if an advanced civilization is able to last more than a few millennia without destroying itself or its world, it will have learned how to master its negative impulses. Perhaps the biggest benefit we can derive from challenging our cosmic mediocrity is the added impetus to learn this lesson ourselves.

To the Editors:

In his recent feature, Howard A. Smith seems to be asserting that the fact of something being rare means that it is necessarily special. This error has been decried by numerous scientists, including Richard Feynman, who mocked the notion in his unique way: “You know, the most amazing thing happened to me tonight.... I saw a car with the license plate ARW 357. Can you imagine? Of all the millions of license plates in the state, what was the chance that I would see that particular one tonight? Amazing!”

If the universe averages one planet with intelligent life per galaxy, Earthlings would never detect other intelligent beings but would nonetheless not be special in any way. In other words, one of 100 billion examples of intelligent life in the universe is hardly special. Frankly, the notion that humans are special is still theological.

John Foster
Columbus, Ohio

Dr. Smith responds:

The “ad hoc fallacy” that Feynman illustrates is not applicable to this situation. “The state” cited in the example has millions of other license plates, and each one is indeed equally “amazing” a priori. But the universe has no other intelligent life we have seen (nor do we know whether any exists). We are an example of one. If a person responds that we are just a collection of molecules in a universe filled with lots of planets and molecules, then it is important to include the “priors” of the case before calculating the statistics, as one would in a detailed Bayesian analysis: If one knows ahead of time that the very particular license number “ARW 357” entitles one to win $1 trillion, then one must admit that all other license plates are worthless. We don’t know whether the collection of intelligent molecules here on Earth is so very particular, but it might be.

We moderns are becoming accustomed to living with the realization that some things are fundamentally not knowable: quantum mechanical predictions, the outcome of deterministic but chaotic systems, and events in the universe beyond our (receding) cosmic horizon are examples.

My article asks the reader to puzzle over three consequences of the limits of knowing (and I talk more about these matters in the 2016 Zygon article I cite). (1) Living with uncertainty: From what we do know, for hundreds or thousands of human generations (maybe even longer) we are likely to be the only intelligent beings around, though we probably will not know for sure that we are. (2) Recognizing beliefs: Yes, we might nonetheless prefer to believe we are cosmically average—or the opposite: that we are a cosmically amazing species. But personal beliefs such as these are matters of taste, and it is worth asking ourselves what underlies that belief. Perhaps some philosophical attachment or psychological need prompts us to see ourselves as being either insignificant or significant. Still, we must try to ground our personal beliefs in the scientific facts. (3) Admitting we are rare: While we wait, perhaps forever, to find out whether there are aliens, we meanwhile ought to recognize that in the volume of the universe in which Homo sapiens can ever exert influence, which is perhaps thousands of light years in diameter, we are probably unusual and could be unique. Does that make us rare, that is: “a thing not found in large numbers and so of interest or value?” I would say so. The Earth is too. The word “special” Dr. Foster uses is loaded with subjectivity and I try to avoid it. Both Dr. Foster, whom I thank for his question, and I are probably average examples of Homo sapiens, but I daresay we are both special. It does not follow that if we are special and intelligence is rare, a theological explanation is required.