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Our future, our universe, and other weighty topics


Thursday, January 12, 2017

Dubious Facets of the SETI Sales Pitch

SETI is the scientific search for extraterrestrial intelligence, primarily by using radio telescopes. When I went to the homepage of the SETI Institute (SETI.org) on January 2, 2017, the first thing I saw was a great big red “Donate Now” button. I have a rule about donating to organizations: I insist that they show no signs of being anything less than completely straightforward and candid. But does the SETI Institute meet such a criteria?

The crucial question you should consider before donating to the SETI Institute is: what are the chances that success will be achieved, and that some radio signals will be discovered from extraterrestrial civilizations? That depends on what the chances are of intelligent life existing elsewhere in our galaxy. The SETI Institute has a FAQ page, and one of the “frequently asked questions” is “Why do we think that life is out there?” This is the entire answer given in the FAQ.

Over the last half-century, scientists have developed a theory of cosmic evolution that predicts that life is a natural phenomenon likely to develop on planets with suitable environmental conditions. Scientific evidence shows that life arose on Earth relatively quickly (only 100 million years after life was even possible), suggesting that life will occur on any planets that have the requisite characteristics, such as liquid oceans (either on the surface or underground). With the recent discovery that the majority of stars have planets – the number of potential habitats for life has been greatly expanded.
In addition, exploration of our own solar system and analysis of the composition of other systems suggest that the chemical building blocks of life – such as amino acids – are naturally produced and very widespread. There are several hundred billion other stars in our Galaxy, and more than 100 billion other galaxies in the part of the universe we can see. It would be extraordinary if we were the only thinking beings in all these vast realms.

This answer is questionable. Let's start with the first sentence: “Over the last half-century, scientists have developed a theory of cosmic evolution that predicts that life is a natural phenomenon likely to develop on planets with suitable environmental conditions.” This strongly implies that during the past 50 years there has been some revolution in our understanding of the likelihood of life developing on a random planet the right distance from a star. But no such thing has occurred. Thinking on this matter is pretty much as it was 50 years ago.

Far from having any theory that predicts that life is likely to arise whenever there are suitable environmental conditions, we still have a set of facts that seem to suggest the opposite. We know that even the most primitive life would require self-replicating molecules, a genetic code that acts like a complex system of symbolic representations, and proteins that seem fantastically improbable to have arisen by chance. Then there's the difficulty of accounting for the origin of the very complex machinery in cells. The facts we have discovered are still quite consistent with the idea that the origin of life would be unlikely to occur on one planet in a trillion, because of the unlikelihood of these things all occurring because of lucky chemical accidents.

The second sentence in the FAQ answer is: “Scientific evidence shows that life arose on Earth relatively quickly (only 100 million years after life was even possible), suggesting that life will occur on any planets that have the requisite characteristics, such as liquid oceans (either on the surface or underground).” SETI enthusiasts have been making this claim for decades, but it is very dubious indeed, relying on two assumptions: (1) that the earth's oceans appeared about a billion years after the earth formed; (2) that life also originated about a billion years after the earth formed.

Our planet is 4.6 billion years old, and claims are made that there are geological signs of life dating back to 3.5 billion years. But such claims are doubtful, as they rely on what are called stromatolites, unusual-looking geological features which some claim were formed by bacteria. We see no cells or biological structures in the oldest stromatolites. The claim that very old stromatolites (older than 3 billions years) are signs of ancient life relies on a rather complicated and debatable line of reasoning. It's quite possible that they are not signs of early life, and that there are alternate geological explanations. This scientific paper says the evidence for life older than 2.5 billion years is “meager and difficult to read.”

Moreover, as discussed here, many scientists think that the earth's oceans are almost as old as the earth itself, having been brought here by comet bombardments. If that assumption is true, there may have been as much as a billion years between the time when life first had a chance to arise on our planet, and the time that it first did arise. If the shaky claims about the oldest stromatolites are in error, there may have been as much as 1.5 billion years between the time when life first had a chance to arise on our planet, and the time that it first did arise. So the claim long made by SETI enthusiasts that life arose here on our planet “almost at the first opportunity” is quite doubtful.

Even if it were true that life on Earth arose 100 million years after it first had the opportunity to arise, this would not be a strong reason for thinking that life in the universe is common. Consider this case. You open your new pastry shop one day, and within an hour someone comes in trying to order a pizza. The chance of this happening is very low. You would be mistaken if you reasoned that the chance of such a thing happening must have been high, or else it would not have occurred within the first hour of your shop being open. You are not entitled to draw such conclusions based on the timing of a single occurrence.

The article here states the following by MIT professor Joshua Winn (referring to this scientific paper):

There is a commonly heard argument that life must be common or else it would not have arisen so quickly after the surface of the Earth cooled," Winn said. "This argument seems persuasive on its face, but Spiegel and Turner have shown it doesn't stand up to a rigorous statistical examination — with a sample of only one life-bearing planet, one cannot even get a ballpark estimate of the abundance of life in the universe."

The next claim in the SETI FAQ answer is: “In addition, exploration of our own solar system and analysis of the composition of other systems suggest that the chemical building blocks of life – such as amino acids – are naturally produced and very widespread.” This is true, but ignores the fact that you can't estimate the probability of something complex arising merely from the availability of building blocks. A big auto parts store may have all the ingredients for a car, but the chance of such ingredients forming into a car when a tornado passes by is presumably very, very low.

The same type of misleading talk is served up by a recent book on SETI by astrobiologist David Grinspoon. On page 339 of his book Earth in Human Hands, he states this:

Much that we have learned in over a half century of space exploration seems to tell us that life and complexity are bound to be anything but rare. The basic ingredients and conditions that facilitated the origin and evolution of life here seem to be widespread throughout the universe.

The first sentence is not at all true, and does not follow from the second statement. Everything we have learned from space exploration is still completely consistent with the hypothesis that the appearance of life is a virtually miraculous event that we would not expect to occur on more than 1 planet in a trillion. You cannot make conclusions about the likelihood of great functional complexity arising from the mere availability of ingredients. There may be all the ingredients for a car in a large auto parts store, but that certainly does not allow us to conclude that is likely that one day such ingredients will randomly assemble into a car. 

It is true that there may be some kind of purposeful cosmic teleology that assures life is common in the universe, but our SETI experts seem to never appeal to such a possibility, relying on dubious kind of "the ingredients are there, so it will happen" reasoning. 

When asking for donations, SETI experts can gain an advantage if they make it look like searches for extraterrestrial intelligence are a fairly new undertaking. People are more likely to donate to a promising new project than some longstanding project that has failed so far. So if I tell you there is a promising new cancer drug called thorsmixadine, and that I need some money to fund initial research on it, you will be much more likely to donate to such a project than if I had told you, “They've spent 400 million dollars researching this drug, with no positive results; but I want to spend even more money, so can you can please help?”

In testimony before the US Congress in 2014, the leading SETI scientist Seth Shostak made these claims giving the impression SETI was some fairly fresh project:

We have only begun to search...The fact that we haven’t found anything means nothing. It’s like looking for megafauna in Africa and giving up after you have only examined one city block.

Such statements were misleading. By the year 2014 SETI had been going on for decades, and scientists had checked many thousands of stars for extraterrestrial radio signals. For example, there was Project Phoenix in the 1980's consisting of 2600 hours of observations, using the world's largest radio telescope. A similar project was the SERENDIP project. And when Shostak made his testimony in mid-2014, most of the work reported in this scientific paper had been done. The paper describes a negative search for radio signals coming from 9293 stars, consisting of 19000 hours of observations carried out between May 2009 and December 2015.

An appropriate theme song for SETI would not be the Carpenters' hit We've Only Just Begun but a song with the same tune but different lyrics:

We haven't just begun...to search
So many stars we've checked
But we keep getting nothing at all
We haven't just begun

If our SETI scientists were to be more candid and frank, they would put away their “it's almost a sure thing” talk and put away their “we've only just begun” talk. They would instead give a very candid pitch for donations like the one below. It would probably raise less funds, but at least it would be forthcoming. 

SETI