Physics, Earth & Space Icon Physics, Earth & Space

The Silence of the Space Aliens

Image credit: NASA Universe, via Flicker (cropped).

National Geographic jokes about the silence of the space aliens.

For more than 50 years, we’ve been eavesdropping on the cosmos, searching for transmissions that would reveal the existence of intelligent, extraterrestrial life.

To date, nobody’s bothered to call.

Is it something we said?

As the silence keeps up, the alternatives get narrow. (1) We are alone in the universe as intelligent beings or (2) “the morbid alternative: Intelligent life periodically emerges on other worlds, but has an unfortunate tendency to self-destruct.” (3) A third possibility is that aliens know about us but cloak their presence for some reason.

Possibility #2, that alien civilizations have a tendency to self-destruct, has been seriously considered by some who look at humans’ bad example of creating devastation “during our relatively brief span as the dominant species on this planet.”

That’s why a trio of scientists recently published a guide to help astronomers detect alien apocalypses — whether it’s the chemical signature of a world filled with rotting corpses, the radioactive aftermath of nuclear warfare, or the debris left over from a Death Star scenario where an entire planet gets blown to bits. [Emphasis added.]

Extinct Aliens and the Design Inference

We see here the makings of a design inference. It might be called Cosmic Forensics. Since forensics is a type of intelligent design science (e.g., determining whether a death was natural or intentional), why not apply the same principles to alien beings? It is, after all, a search for extinct extraterrestrial intelligence (SEETI). That’s a goal far beyond astrobiology, the search for biomarkers that could indicate life down to the microbial level. SETI and SEETI are looking for beings “at least as clever as we are,” as Seth Shostak likes to say.

The clues for SEETI could be very indirect and faint:

SEETI research, however, is not looking for biosignatures — signs of life. Instead, scientists have to hunt down necrosignatures — signs of death — that would indicate destruction on a colossal scale.

Consider a scenario in which biological warfare rapidly wiped out a planet’s population. Microorganisms that cause decomposition would gorge themselves on alien corpses. In doing so, they would excrete chemical compounds, dramatically increasing the levels of methane and ethane in the atmosphere.

If the population size of the alien world were comparable to that of Earth, the methane and ethane gases would dissipate in about a year, so there would be only a short window of opportunity to detect the cataclysm.

However, if the biological arsenal included a genetically modified virus capable of jumping species, then the planet’s casualties might also include its animal life. In that case, the telltale signs of catastrophic biowarfare could be visible for several years.

The leftover glow of a nuclear holocaust could be another clue. Planets don’t typically nuke themselves. Some intelligent cause would have had to push the button.

Evidence of Intention

It’s repulsive to think about global destruction, but intelligent design doesn’t distinguish moral purposes from immoral ones. ID merely looks for evidence of something intentional. Like SETI, SEETI depends on the researcher being able to tell the difference between a purposeful act and a natural act.

SEETI thinkers even consider “speculative technologies” of aliens. If advanced civilizations create self-replicating nanobots that run haywire, they could reduce a planet to a “grey goo” of dust where once an intelligent society thrived. 

But, what sort of evidence would exist for this heinous act? One remote possibility is the detection of artificial compounds in the debris disc, indicating that the planet was once home to a technologically-advanced civilization.

A “heinous act” is an intentional act, implying moral and intellectual responsiblity. We don’t call a lion taking down a wildebeest “heinous.” Something unnatural has happened.

More of the Same?

Perhaps, as evolutionists, the trio of scientists contemplating SEETI as a research program view human planetary destruction on a continuum with animal death — just a particularly egregious advanced form of ecological collapse. Why, then, call it SEETI with emphasis on the “I”? Animals like birds and dolphins have intelligence. Is human intelligence just more of the same? 

Their language betrays something unique about human intelligence that carries over to alien intelligence. They talk about warfare. Animals have predator-prey relationships, but they don’t engage in warfare. Animals don’t “genetically modify” other organisms for the purpose of wiping them out. Animals don’t create “artificial compounds” that can be distinguished from natural compounds. 

The SEETI thinkers are looking for signs of intention. Even in global death, they believe they could separate natural causes from intelligent causes. That’s the design inference.

This article was originally published in 2015.