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Our future, our universe, and other weighty topics


Thursday, October 12, 2017

SETI Success Before 2035 Is Very Unlikely Unless There Is Teleology

In my favorite spot for finding unwarranted claims by scientists (the Nautilus web site), there is a recent post by astronomer Seth Shostak entitled “Why We’ll Have Evidence of Aliens—If They Exist—By 2035.” Shostak tries to argue that the great big pie-in-the-sky of “signals from extraterrestrials” will be delivered within a decade or two. But his argument is very unconvincing.

Shostak's argument essentially boils down to merely saying something kind of along the lines of we're looking real hard, in more ways, in more places, and with more frequencies, and that will do the trick. Shostak mentions optical SETI, the search for optical pulses from extraterrestrials (a bit like getting a flashlight signal across the stars). The way he describes things, you might think that this type of search was in its infancy. But, to the contrary, a scientific paper not mentioned by Shostak reported on a search for optical signals coming from sun-like stars. Almost 5,000 such stars were searched over the course of two years, but no such signal was found.

Shostak also tells us, “There is a completely different approach that has yet to be explored in much detail: to look for artifacts—engineering projects of an advanced society.” From the way he writes, you'd think that no one had done such a search. But Shostak fails to mention a search of 100,000 nearby galaxies looking for signs of extraterrestrial engineering, a search that came up empty.

The main way of searching for extraterrestrial civilizations is to attempt to pick up radio signals from other planets. Shostak tells us, “Within two decades, SETI experiments will be able to complete a reconnaissance of 1 million star systems, which is hundreds of times more than have been carefully examined so far.” Hundreds of times more? That would only be true if fewer than 5000 stars had been searched so far. But this paper alone discusses 9293 stars that were unsuccessfully searched for extraterrestrial signals. Were we to add up the total number of stars searched for radio signals by astronomers, in 50 years of SETI efforts, it would be a number much greater than 9293.

Shostak talks about two approaches to searching for extraterrestrial signals: “One is to scan as much of the sky as possible; the other is to zero in on nearby star systems.” He suggests the second approach is better, saying that if extraterrestrials live on planets, “It’s better to devote precious telescope time to examining nearby star systems.” But a 2006 article says, “Recent work confirms long-standing suspicions that star-by-star targeting should be abandoned in favor of scanning the richest star fields to encompass very large numbers of stars, even if most of them are very far away.” That's the approach that has already been taken by projects such as the SERENDIP project. But they came up empty.

Shostak then states the following:

SETI practitioners from Frank Drake to Carl Sagan have estimated that the galaxy currently houses somewhere between 10,000 and a few million broadcasting societies. If these estimates are right, then examining 1 million star systems could well lead to a discovery. So, if the premise of SETI has merit, we should find a broadcast from E.T. within a generation.

Such estimates are just examples of picking numbers out of a hat, and both of the people Shostak sites were astronomers, not people with degrees in biology. There are very strong reasons for believing that unless there is something special going on in terms of cosmic teleology, something to better the long odds, the chance of extraterrestrial civilizations arising anywhere else in our galaxy are very low.

Lets consider some of the things that need to go right in order for a communicating civilization to arise on another planet:
  1. Life has to begin, consisting of cells that would have to be very complex for even the simplest life.
  2. At about the same time, a genetic code has to somehow arise.
  3. Life has to progress from the simplest cells (prokaryotes) to the vastly more complicated cells called eukaryotes.
  4. Life has to progress to macroscopic life with complicated organ systems.
  5. Macroscopic life has to evolve into intelligent life.
  6. Intelligent life has to develop both language and limbs sufficient to make tools, as well as the advanced consciousness and abstract thinking needed for a species to have an interest in communicating with other species on other planets.
The first of these things is something that seems so unlikely to occur by chance that we should not assume it has accidentally occurred even one other time on billions of other planets in our galaxy. Darwinian ideas are of no value in explaining life's origin, since natural selection can only occur when life exists. Even the most primitive microorganism known to us seems to need a minimum of more than 200,000 base pairs in its DNA (as discussed here).

The origin of even the simplest life seems to require fantastically improbable events. Protein molecules have to be just-right to be functional. It has been calculated that something like 1070 random trials would be needed for a functional protein molecule to appear; and many such protein molecules are needed for life to get started. And so much more is also needed: cells, self-replicating molecules, a genetic code that is an elaborate system of symbolic representations, and also some fantastically improbable luck in regard to homochirality. Homochirality is the fact that in a laboratory the components of sugars and amino acids are chemicals that are “left-handed” or “right-handed” in equal numbers, but in living things essentially all sugars are made of “right-handed” components and all proteins made of “left-handed” components – a situation that seems fantastically unlikely to have occurred by chance.

If by some miracle life were to arise on a planet, from a naturalistic perspective it seems extremely likely that cells would simply stay stuck in a prokaryotic state, rather than making the leap to the much more complicated eukaryotic cells. The prevailing theory (or perhaps one should say “fairy tale”) on how such a leap occurred is not even a Darwinian explanation, but a very far-fetched endosymbiosis story involving “incorporation by ingestion” that tries to kind of say, “Cells got vastly more complicated by eating other cells.” We are asked to think that a biological organism could become vastly more complex just by gobbling up other things. In the recent book Aliens, biologist Matthew Cobb gives a description of current thinking on this topic, emphasizing the improbability of it:

What happened on Earth – known as eukaryogenesis – was not the product of random mutation and the subsequent sifting of acquired characters that have differential fitness (the essence of natural selection). Instead there appears to have been a single event of mind-boggling improbability, for it involved two life forms interacting in a most novel way....Prior to that moment, all life had consisted of small microbes with no cell nucleus and no mitochondria. Everything changed when one unicellular life form, known as an archaebacterium, ended up inside another, called a eubacterium.

On another page Cobb says this:

We could in principle calculate the probability of the appearance of eukaryotes, but we would soon run out of zeros...That weird hybrid was our ancestor, and its existence – and therefore ours – was incredibly improbable. As far as we are aware, no such event happened before or since.

It also seems extremely likely that life would just stay in a microscopic state rather than making the leap to multi-cellular life forms consisting of multiple layers of organization such as cells, tissues, organs and organ systems. On Earth this seems to have happened in a sudden burst, at about the Cambrian Explosion about 540 million years ago. Scientists have never adequately explained this sudden blossoming, in which most major phyla of animals suddenly appeared.

To plausibly explain the appearance of large, multi-cellular, macroscopic life consisting of cells, tissues, limbs, organs, and organ systems, we would need a theory explaining gigantic amounts of biological organization. But we don't have that – merely something vastly less, the theory of accumulation that is Darwinism (a theory of the accumulation of favorable random mutations). 

To clarify the difference between the two (organization and accumulation), below we see a depiction of organization, the metabolic pathways in the human body:

metabolism
    Credit: US Department of Energy

And here is an example of accumulation:


Then there are the difficulties of explaining the appearance of intelligent life, the type of life that might be interested and capable of interstellar communication. In the case of humanity, we have a species with about 10 fundamental mental characteristics that separate us from the animals: things such as abstract thinking, language ability, mathematical ability, philosophical ability, spirituality, ethics, altruism, self-consciousness, and intellectual curiosity. As argued here, none of these things increased the ability of humans to survive in the wild, so we cannot explain such things as being due to natural selection. 

In moments of candor, some evolution experts such as George Gaylord Simpson and Ernst Mayr argued that the appearance of humanity was such a fluke that we should not at all expect it to happen on any other planet in the galaxy. In the recent book Aliens, biologist Matthew Cobb states that “a study of the key points in life's history” leads us to the pessimistic conclusion that “there are no alien civilizations.”

You can summarize the situation as follows: based only on what we currently know for sure, if an extraterrestrial planet existed the right distance from its sun, with overwhelming likelihood no life would arise on the planet; and if life did by great luck appear on the planet, it would with overwhelming likelihood stay in the simple prokaryotic microscopic state; and if the vastly more complex eukaryotic microscopic state did by great luck arise, with overwhelming likelihood the planet would never see multi-cellular life with limbs and tissues and organ systems; and if by great luck very organized multi-cellular life arose, it would with overwhelming likelihood not reach anything like the consciousness, linguistic fluency and manual dexterity needed for interstellar communication.

Given such a reality, there is no basis for the estimates Shostak cites for the number of communicating civilizations in our galaxy (between 10,000 and a million). If we realistically consider things based purely on known biology and chemistry, without assuming anything special helps life along, our best guess should be that there is no other civilization in our galaxy. There are billions of other galaxies, so such an estimate would not preclude there being many other civilizations scattered across the universe's galaxies. But the chance of communicating with a civilization in another galaxy is remote. The fact that SETI has been searching for extraterrestrial civilizations for decades without finding anything is consistent with an estimate that we are the only civilization in our galaxy, and is rather inconsistent with claims that there are 10,000 or more extraterrestrial civilizations in our galaxy.

But there is one reason for thinking that there might be many civilizations in our galaxy. Given the seemingly terrible odds of intelligent life appearing even once in a galaxy, it may be best to assume that there must have been some special “X factor” that helped intelligent life appear. We can use the vague term “cosmic teleology” to describe such a thing. A kind of “big umbrella” term that can cover many possibilities, the term “cosmic teleology” covers everything from the possibility of deliberate supernatural assistance to the possibility that there is some kind of cosmic life-force that causes biological life to become progressively more organized. The fact that many a biologist has declared such a concept to be taboo and forbidden is no reason at all why we should avoid it.

A believer in cosmic teleology can be a believable optimist when it comes to the search for extraterrestrial intelligence (SETI). For example, such a person might maintain that we will succeed in finding extraterrestrials within 50 years, because there is some cosmic life-force that acts throughout the galaxy, causing life to appear on every habitable planet, and also causing life to become  ever-more organized. But someone who has not articulated any doctrine of cosmic teleology is not a believable short-term optimist about SETI. Similarly, if you have for some reason a compelling theory you can count cards or read minds or influence the rolls of dice with mind-over-matter, you might have a good basis for optimism about going to Las Vegas and coming back with $100,000 in winnings; but if you have no such theory, you have no business being optimistic about such an outcome.

As for Shostak's claim that we will make contact with intelligent extraterrestrials within 20 years (because the search technology is getting better and better), it seems no more convincing than the claim that we will be able to telephone the dead within 20 years, because smartphones are getting better and better. 50 years of SETI failure suggests that if extraterrestrial civilizations exist, they are very hard to find, and that it is unlikely that we will find any extraterrestrial civilizations within the next 20 years.