A Brief-ish History of SETI. Part VII: Brief Windows and Transcendence - Universe Today

The Drake Equation: a mathematical formula for estimating the probability of finding advanced civilizations in the Universe. Credit: University of Rochester

Welcome back to our continuing series on the Brief-ish History of SETI. In our previous installments, we looked at the early history and the first experiments in the Search for Extraterrestrial Intelligence (SETI), followed by the first example of a modern SETI survey (Project Ozma) led by famed Cornell professor Frank Drake, the Drake Equation, and the enduring legacy of both. This was followed by some of the most enduring theories about what advanced civilizations might look like, including our own someday.

Next, we examined the first attempt at Messaging Extraterrestrial Intelligence (METI) and what is still considered the best candidate for an extraterrestrial signal (the Arecibo Message and the WOW! Signal), followed by the first physical message sent to interstellar space. And in our last installment, we examined two fundamental (and related) theories on why humanity has neither seen nor heard from an advanced extraterrestrial civilization (ETC), and the possible implications for humanity.

Today, we will examine some of the more practical suggestions as to why humanity has neither seen nor heard from an advanced extraterrestrial civilization (ETC), consistent with many of the arguments Sagan and Newman argued in their seminal paper (nicknamed "Sagan's Response"). We'll also examine some of the most mind-blowing and exotic explanations that take the concept of advancement in a whole different direction (and a whole different level!).

The Longevity Factor

First up, there's what this author likes to call the "Brief Window Hypothesis," a proposed resolution to the Fermi Paradox that takes its cue from Frank Drake himself and from what he claimed was the most important parameter in his famous equation. This was none other than the time an extraterrestrial would have to transmit messages into space (L), otherwise known as the longevity factor. Basically, Drake posited that the lifetime of a civilization is finite, which was inspired by the very real possibility of nuclear annihilation during the Cold War.

This parameter has also inspired proposed resolutions to Fermi's Paradox. One of the earliest examples came from German astrophysicist and radio astronomer Sebastian von Hoerner, a colleague of Frank Drake's who participated in Project Ozma. In 1961, he penned a paper titled "The Search for Signals from Other Civilizations," in which he argued that the existential window of a technologically-advanced civilization might be too short relative to the time it would take to make contact with another intelligent species. As he wrote:

We should not underestimate the power of two critical factors that can terminate the life of a civilization once the technical state has been reached. Science and technology have been brought forward (not entirely, but to a high degree) by the fight for supremacy and the desire for an easy life.

Both of these driving forces tend to destroy if they are not controlled in time: the first one leads to total destruction, and the second one leads to biological or mental degeneration. In summary, we assume that a state of mind not too different from our own will have developed at many places but will have only a limited longevity.

Another issue with most proposed resolutions to Fermi's Paradox is the inherent assumption that advanced civilizations will experience exponential growth. In contrast, some researchers have presented scenarios in which ETIs were unable to sustain this growth pattern, which is why none have succeeded in becoming a galactic civilization. In 2009, Jacob D. Haqq-Misra of the Blue Marble Space Institute of Science (BMSIS) and Seth D. Baum of the Global Catastrophic Risk Institute (GCRI) argued this very point in a study titled "The Sustainability Solution to the Fermi Paradox."

Essentially, they ventured that "[t]he absence of ETI observation can be explained by the possibility that exponential or other faster-growth is not a sustainable development pattern for intelligent civilizations." Drawing on lessons from human history, Haqq-Misra and Baum showed that exponential growth has been a common feature, often to the detriment of the civilizations involved. This has led geologists to coin the term "Anthropocene," which acknowledges that humanity is currently the single greatest determining factor in Earth's evolution.

When applied to exo-civilizations, they claimed, the same tendency could explain why we don't hear from aliens:

The Fermi Paradox ultimately concerns the spatial expansion of civilizations, but spatial expansion is closely linked with expansion in population, environmental impact, and resource consumption. For example, migration is often driven by resource shortages, which in turn may result from...