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Our future, our universe, and other weighty topics

Monday, December 9, 2019

Misstatements and Dubious Claims of Carl Sagan

Carl Sagan was a scientist who enjoyed great influence in the 1970's and 1980's.  In books, a weekly column and a television show (the original version of the Cosmos series), Sagan advanced rather dogmatically a set of ideas that were widely influential. His ideas are summarized in the visual below depicting stone tablets:

Reality according to Carl Sagan

When I was a young man in my early twenties, Carl Sagan was at the height of his influence, and I bought quite a few of these ideas. But now quite a few of these ideas seem dubious or untenable. As a whole, the Sagan Creed lacks coherence, and parts of it seem to contradict other parts of it. For example, if it were true that the galaxy was teeming with so many extraterrestrial civilizations, why should we not expect that some of them are visiting us now, or have visited us in the past? And if mere chance is behind the origin of life, why should it be that extraterrestrial life should be common? Given the immense improbability of life appearing by chance from lifeless chemicals, it would seem that if mere chance is controlling things, that extraterrestrial life should be very rare or nonexistent. And if there are extraterrestrial civilizations millions of years older than us, why should we think that we would be able to communicate with them using radio? You would think such godlike entities would have some far more sophisticated means of communication. 

Let us look at an interview Carl Sagan gave to the magazine Rolling Stone in 1980, at the height of his influence. Defending the theory of evolution by natural selection in his interview, Sagan provides no evidence that anything has actually been produced by such a process. He merely states, “It’s hard to see how evolution by natural selection wouldn’t work.” To the contrary, anyone examining the unfathomable complexity and information richness of biological organisms should have the strongest reason for doubting that what Sagan mentions should work to produce such wonders. Random mutations can be accurately and concisely described as noise. Darwinian evolution by natural selection can be concisely described as the theory that noise sometimes get incredibly lucky, and that such noise luckily piles up to become incredibly organized systems more functionally intricate than anything humans have created (as well as vast libraries of functional information). It is anything but clear that such a thing could possibly work. People who have good evidence that something works show us the evidence that the thing works. They do not make statements such as “It's hard to see how it would not work.”

Rather suspiciously, while defending Darwinism, Sagan makes an appeal to the claim that we should not rely on common sense. He refers to the “inapplicability of common sense.” He then states the following:

It is true that natural selection as the cause of evolution is a hypothesis. There are other possibilities.”

This does not seem like the ringing endorsement that we might expect if the case for such a cause was very strong.

In the interview Sagan tries to drum up some “the universe helped produce us” enthusiasm by making some very dubious claims. He states this:

Cosmic rays that are produced in the death throes of stars are partly responsible for the mutations that have led to us—the changes in the genetic material. The origin of life was spurred by ultraviolet light from the sun and lightning, which in turn is caused by the heating of the earth by the sun.”

Mutations are noise. The idea that mutations of any type caused the incredibly fine-tuned proteins in humans is no more logical than the idea of typing monkeys producing technical instruction manuals. Since genomes do not actually specify phenotypes,  since DNA is not a blueprint or a recipe for making either human beings or any part of a human being larger than a protein molecule, and since there is no proof or good evidence that any single protein molecule arose from random mutations, it is not a statement of fact to refer to “the mutations that have led to us,” but merely a repetition of a dubious article of faith. 

Sagan frequently spoke and wrote on the topic of the origin of life, but seemed to never deal with it candidly or honestly by discussing the fantastically intricate fine-tuned arrrangements of matter needed to get life started.  His "just add energy" idea that so gigantically improbable an arrangement of matter was “spurred by ultraviolet light from the sun and lightning” was goofy talk, like saying that a lightning storm or wind storm could cause the scattered pebbles on a beach to assemble into a long meaningful message. 

Later in the interview Sagan then makes this ludicrous statement:

We are naturally scientists. It’s the only thing we do substantially better than other creatures.”

Of course, this is nonsense. There are 1001 things that humans do substantially better than other creatures, such as art, philosophy, film-making, education and computer programming.

In episode 2 of the original Cosmos series, Sagan discussed the origin and history of life, using "we've got this figured out" kind of language that was very inappropriate given the subject matter.  Below are some of the weak points in his discussion:

  • After discussing a primordial soup, he claimed that “one day, quite by accident a molecule arose that was able to make crude copies of itself using as building blocks the other molecules in the soup,” failing to tell us that no such self-reproducing molecule has ever been produced under experimental conditions simulating the early Earth, and that not even any  building blocks of such a molecule (nucleosides) have been produced in experiments simulating the early Earth.
  • He explained the origin of the first cell by merely mentioning molecules and by stating “varieties with specialized functions joined together making a collective...the first cell,” failing to mention that a self-reproducing cell would require about 100 different types of such molecules “with specialized functions” (100 different types of protein molecules), that every one of these different types would be as complex (and as unlikely to form by chance) as a well-functioning 100-word computer program, and that there is not the slightest reason why such molecules “with specialized functions” (needed by a cell) would happen to exist prior to the existence of the first cell, making this “joining together” a miracle of luck if it occurred by chance.
  • He completely ignores the problem of explaining eukaryotic cells, which are not explained by anything he discussed.
  • He handles the mountainous problem of explaining the appearance of multicellular organisms merely through the not-very-helpful explanation that one-celled organisms "joined together," which sounded as vacuous as the "stuff joined together" explanation he gave to explain the appearance of the first cell. 
  • He states, "Then, suddenly...there was an enormous proliferation of new life forms, an event called the Cambrian Explosion," without doing anything to explain how that could occur, and without noting how such an event is inexplicable using only the gradualist explanations he has previously given. 

In episode 2 of the original Cosmos series, Carl Sagan stated the following utterly fallacious logic (which was repeated by Neil de Grasse Tyson in the second Cosmos series): 

"But if artificial selection makes such changes in only a few thousand years what must natural selection working for billions of years, be capable of? The answer is all the beauty and diversity in the biological world."

Read more: https://www.springfieldspringfield.co.uk/view_episode_scripts.php?tv-show=cosmos-carl-sagan&episode=s01e02

This statement commits a logic error. It would be logically correct to make a statement like this:

"If wind erosion can produce a 1% deformation in something in 10 years, how much of a deformation might wind erosion produce in 500 years? Easily 20% or more."

But by asking us to draw a conclusion about the power of natural selection (something blind and unguided) from the power of artificial selection (something guided by human choices), Sagan committed a logic error as bad as the logic error in the statement below:

"If non-blind painters can paint 100 landscape masterpieces in 200 years, how many landscape masterpieces might blind painters have painted in 500 years? Easily hundreds."

In episode 11 of the original Cosmos TV series, Sagan spoke as if scientists knew how a brain could store memories, claiming that every brain connection represents one bit of information: "What we know is encoded in cells called neurons...every connection representing one bit of information." In neither his time nor our time does any scientist have a detailed credible theory as to how a brain could either encode or store human episodic and conceptual information by any physical means, and there is zero evidence that  human memories are stored or encoded as digital information involving bits. Any theory of a digital storage of human memories in the brain is ruled out by the short lifetimes of the protein molecules in brains, which last for only weeks. Talking on and on about the brain, Sagan presented no actual evidence of having any understanding of how a brain could perform any of the higher mental human capabilities,  other than the vague idea that thought comes from the frontal cortex, an idea discredited here

Stating very dogmatically an element of the Sagan Creed listed above, Sagan began episode 12 of the original Cosmos TV series by stating,  "In the vastness of the cosmos there must be other civilizations far older and more advanced than ours."  It is certainly not true that there "must be" such extraterrestrial civilizations, for a variety of reasons. The first is the vast mathematical improbability of life ever arising from chemicals by mere chance processes.  The second is the almost equally vast improbability of life ever reaching a state of multicellular organization and intelligence by chance processes. The third reason is the very significant chance that any civilization arising would not last for more than a few centuries or millenia after it achieved atomic power.  Sagan stated, "Extraordinary claims require extraordinary evidence," but did not apply such a principle to prevent himself from making extraordinary claims about the existence of civilizations far more advanced than ours, claims not supported by any evidence. 

At about the 1:09 minute mark in the interview here,  Sagan claimed to understand the nature of humanity's status in the galaxy. He stated, “If you look at time scales, you realize that our civilization is the most backward civilization in the galaxy that can communicate.” Of course, we know nothing of the sort. If life is common in the galaxy, there could easily be many other communicating civilizations that are more backward than our own. 

At about the 2:15 mark in the interview Sagan began to tell a great big falsehood related to extraterrestrial life.  He stated the following:

"The carbon-rich complex molecules that are essential for the kind of life we know about, are fantastically abundant. They litter the universe. We see them in asteroids, and comets, and the moons and the outer solar system, and even in the cool dark spaces between the stars. So the stuff of life is everywhere."

He thereby led his listeners to think that “stuff of life” has been discovered in outer space. No such thing has occurred. The “stuff of life” would be things such as nucleic acids and proteins, and they have never been discovered in outer space. There are virtually no signs of the building blocks of life in outer space. None of the twenty amino acids used by living things has been discovered in space, other than the simplest amino acid, glycine (which was not found in space while Sagan lived). Sagan frequently repeated this "stuff of life is everywhere" falsehood in a variety of places. 

In an interview on January 1, 1995, Sagan suggested that planet Earth is very insignificant, partially on the grounds that  "this universe is one of an enormous number, maybe even an infinite number, of other closed off universes," a claim for which there is no evidence whatsoever.  But so it was in Sagan-speak: facts all mixed up with speculation, and the strange mixture sold as "science." In the same interview, Sagan sunk into pure nonsense talk by claiming that "all of our vaunted uniqueness turns out to be shared with other animals," a statement that can be very quickly disproved by referrring to the simple fact that only humans speak and do philosophy and write books and have abstract ideas. 

Quite misleadingly in this 1995 interview, astronomer Sagan says nothing about the evidence that the universe is only 13 billion years old, and seems to suggest that the universe has existed forever. He states this:

"We expect the universe to go on forever into the future. Why do we have the idea that it doesn't go on forever into the past?"

The answer to this question was well-known to every professional astronomer in 1995: that the expansion of the universe (known by the redshift of galaxies) and the cosmic background radiation tell us that the universe had a unique sudden origin about 13 billion years ago.  

One of Sagan's last writings was The Demon Haunted World: Science as a Candle in the Dark, a book on the topic of paranormal phenomena.  The long book shows quite a bit of erudtion and has quite a few scholarly flourishes, but the erudition is mainly concerning extraneous or tangential topics. Sagan showed zero signs of having seriously researched any of the better evidence for paranormal phenomena.  He shows no sign of having read any of the 40 most important books he should have read before writing on such a topic. 

On page 259 of that book, Sagan repeated what I call the Great DNA Myth, the hugely misleading and utterly erroneous claim that DNA is a specification for making a human being.  He stated, "Molecular biologists are busily recording the sequence of the three billion nucleotides that specify how to make a human being." That job was finished in the year 2003 when the Human Genome Project was completed, and no such specification of "how to make a human being" was ever found in DNA or its nucleotide sequences. When Sagan wrote the words, we already knew why DNA could not possibly be a specification of "how to make a human being," because we knew that DNA only specifies low-level chemical information such as the amino acid sequences of proteins, not higher-level structural information such as how to make a cell or an organ or organ system or a human.

A DNA molecule bears not the slightest resemblance to either a blueprint for making a human being, or a set a instructions (a recipe or program) for making a human being.  DNA does not specify how to make any full organism. DNA does not specify how to make any organ system or appendage of any organism. DNA does not specify how to make any organ of any organism. DNA does not even specify how to make any of the 200 types of cells used by humans. But in episode 11 of the original Cosmos TV series,  Carl Sagan made the very fictional claim that DNA is "a complete library of instructions of how to make every part of you." 

Telling a human that he originated because some DNA blueprint was read (when nothing like such a DNA blueprint has ever existed in any human) is a falsehood far more serious than, say, telling a young boy that his father is not the doctor he lives with, but some unknown truck driver.  Both are gigantic falsehoods regarding a person's origin, and the first of these is far more serious a lie. Misidentifying someone's father is at least in the right ballpark (both the doctor and truck driver being humans). When a person believes that he arose because of the reading of a DNA body blueprint (something that has never existed in any human), he will get an idea about his origin that is not at all in the right ballpark; and as a result he may get a "a human is just chemistry" idea that is both false and morally corrosive. 

Apparently not ever having bothered to seriously study any of the massive evidence for paranormal psychic phenomena inexplicable by brain activity, nor having bothered to study any of the massive neuroscience evidence suggesting that the mind and memory cannot be explained by the brain (such as the fact that people with half brains or quarter brains can think and remember very well), Sagan made the claim that there is "not a shred of evidence" for the idea that the mind is more than the brain. This was a misstatement as false as his mythical claim about DNA being a specification of "how to make a human being," and his mythical claim about a "genetic language in which is written the diverse skills and propensities of every being on Earth." Genes (merely small parts of DNA) do not specify how to make a human being, and do not explain any mind skills such as imagination or creativity or abstract reasoning or instant memory recall or moral reasoning. Given the genetic code that limits genes to stating very low-level chemical information such as the amino acid sequences in proteins, it is utterly impossible that a gene could "write a skill" such as how to compose music or how to reason mathematically or how to think philosophically. Sagan promoted the erroneous idea that the brain is "programmed,"  referring to "how cleverly the brain is packaged and programmed." Nothing like software or programming has ever been discovered in a brain. 

Faced with massive reports of near-death experiences, Sagan advanced the silly idea that such things are rememberances of the experience of birth. He suggested that reports of passing through a tunnel toward a bright light are memories of passing through a birth canal and moving towards the light of a hospital.  This idea made no sense for two reasons: (1) people don't remember anything that happened in the first year of their lives; (2) when a baby tightly squeezes through a vaginal birth canal, its eyes are not pointing towards the exit of such a canal; so a being-born baby doesn't actually have a visual experience similar to a near-death experience. 

Although he did good work on some tasks such as alerting people to the dangers of nuclear arsenals, and usually had his heart in the right place, Carl Sagan was someone who pretended to know many things he did not actually know. He stated many of his unproven or dubious dogmas or speculations with such smug assurance that it helped fool many people into thinking that scientists know much more than they do know. And like quite a few of today's professors, Sagan sometimes played fast and loose with the facts to help prop up the speculations or dogmas he was trying to sell. Scientists have done the search for extraterrestrial radio signals that Sagan lobbied for in the 1970's, but they have come up empty-handed, suggesting that Sagan was way off in his estimations of how many civilizations existed in our galaxy.  

Sagan's 13-part Cosmos series was the very model of crowing scientist overconfidence. It would be great if one day someone did a 13-part television series serving as a corrective to such pretentious braggadocio. It might be a series discussing all of the very great limitations of modern knowledge, all of the conflicting signals nature sends us, and all of the many reasons for doubting the dogmatic claims taught by professors pushing their belief systems.  A good title for such a series might be What We Don't Know

Thursday, December 5, 2019

Two More "Basic Facts of Science" Cast Into Doubt

Many of our scientists have a very lamentable tendency to pretend to know things they do not actually know. We see this massively in the world of biology. But we also see it in the world of cosmology, the study of the large-scale physical universe.

For more than 20 years, scientists have presented in their publications and articles a “composition of the universe” pie chart. By presenting such a chart, they are purporting that they understand the makeup or composition of the universe. The typical “composition of the universe” pie chart looks like this:

dogmatic overconfidence

Notice the precision in the chart, including the claim that exactly 71.4% of the universe consists of dark energy. You would never suspect from such precise numbers that such numbers are just shots in the dark or wild guesses. But that's exactly what they are. No one has ever observed any particles of dark energy or any particles of dark matter. Scientists have been searching for such particles for many years, without success. Neither dark matter nor dark energy has any place in the Standard Model of particle physics. 

Claims that dark matter exists are based mainly on the fact that existing theories of gravity do not explain observed behavior of stars as they revolve around the center of the galaxy. The hypothesis of dark matter is only one of many possible explanations for such a discrepancy. There are alternate explanations such as the idea that gravity may work in ways more complicated than we imagine. We don't actually know whether dark matter exists.

Claims about the existence of dark energy are based on evidence that the expansion of the universe is accelerating. It was in the late 1990's that there first arose the belief that the expansion of the universe is accelerating. Around 1998 two groups announced that after studying supernova explosions in distant stars, the groups had come to the conclusion that the expansion of the universe was accelerating. It was claimed that we must believe in dark energy to explain this acceleration of the universe's expansion. Such a claim was always suspect, as dark energy is only one theoretical way to explain why a universe might have an accelerating expansion. But nonetheless, members of these groups (Perlmutter, Schmidt and Riess) won the 2011 Nobel Prize in physics.

But now Subir Sarkar and his colleagues have written a paper (accepted for publication) calling the evidence for dark energy into question. Sarkar and his colleagues have re-analyzed the supernova data, and have concluded that the expansion of the universe is probably not accelerating. The scientists claim that there is a motion of our local region of space that was not recognized by Perlmutter, Schmidt and Riess, and that such a motion caused the scientists to reach the wrong conclusion. Sarkar and his colleagues say, “Thus the cosmic acceleration deduced from supernovae may be an artefact of our being non-Copernican observers, rather than evidence for a dominant component of ‘dark energy’ in the Universe.” If Sarkar and his colleagues are right, two of the top 10 claims of cosmologists (that dark energy exists and that the expansion of the universe is accelerating) are unfounded.  

The issues are highly technical, and it will be some time before the dust settles and we find out which group is right on this matter. For the time being, I may merely note that this seems to be further evidence of the strong tendency of scientists and science writers to start declaring certain things as facts long before any very clear proof has appeared for the things they are calling facts.

In the article here, we have an example of such overconfidence and dogmatism. Fraser Cain (publisher of the Universe Today web site) claims that scientists “know” that dark energy exists. He claims that there are “multiple lines of evidence,” and lists some space probes (Wilkinson and Planck) that studied the cosmic background radiation. He states:

NASA’s Wilkinson Microwave Anisotropy Probe studied the Cosmic Microwave Background Radiation of the Universe for 7 years, and put the amount of dark energy at 72.8% of the Universe. ESA’s Planck spacecraft performed an even more careful analysis and pegged that number at 68.3% of the Universe. Astronomers know that dark energy exists. There are multiple lines of evidence.”

But Sarkar is quoted in Physics Today as stating that the cosmic background radiation “does not directly measure dark energy” and that the idea that it does is a “widely propagated myth.” On this point he is right. The idea that we can understand the composition of the universe by studying the cosmic background radiation makes no sense at all. Being uniform to about 1 part in 10,000, such radiation teaches us very little.

There are quite a few “widely propagated myths” spread about by scientists, whose teachings are often the unproven dogmas of their cherished belief system. Cain has made the mistake of thinking that we can know something is true merely because “there are multiple lines of evidence.” Each of multiple lines of evidence can be weak, and they may add up to no convincing basis for believing in something.  A hundred different dubious beliefs can be supported by "multiple lines of evidence" if there are enough people trying to look everywhere for such evidence.  For example, if you believe that extraterrestrials are currently visiting us, you can point to "multiple lines of evidence" such as UFO sightings, alien abduction stories, strange cattle mutilation incidents and crop circles. 

Cain has also failed to see that an estimate of something is not a determination of something. The fact that two teams of scientists estimated a particular level of dark energy did not mean that they had done anything to establish that such a level exists. An examination of the paper on dark energy published by the Planck team should give you no confidence that the team has any kind of good understanding of how much dark energy there is.  The paper merely claimed to be studying "the implications of Planck data for models of dark energy," not to be providing evidence that dark energy exists.  

When asked about the composition of the universe, the only honest answer for a scientist or a science writer to give is to say that he does not understand such a thing. But instead our scientists have again and again spoken as if they knew things they did not know: that dark energy exists and that dark matter exists. Such dogmatic overconfidence takes a particularly absurd form when we see graphs like the one at the top of this post, in which scientists make claims such as the claim that the universe is “71.4% dark energy,” when they are not even sure that dark energy exists. That's kind of like saying that your girlfriend will live as your wife for 40.7 years before you even ask her to marry you.

Sunday, December 1, 2019

SETI's "We've Only Just Begun" Excuse Versus Historical Reality

SETI (which stands for Search for Extraterrestrial Intelligence) is the scientific attempt to search for extraterrestrial intelligence (civilizations on other planets) by astronomical efforts.  Such efforts have mainly consisted of attempts to pick up radio signals coming from other planets, although sometimes SETI scientists use other techniques such as searching for optical signals.   Thus far SETI has failed to detect any signals from extraterrestrials.

Radio telescopes like this are used for SETI

SETI proponents have long resorted to a rhetorical technique designed to make us think that we should not let such results dampen enthusiasm for making radio searches for signals from other planets.  The technique is to say something along the lines of "we've only just begun to search for life in outer space."  If someone thinks that "we've only just begun" to listen for radio signals from civilizations on other planets, he won't be too discouraged by the lack of success so far. The "we've only just begun" meme works pretty well as an excuse for a lack of results.  But if a person tries to bolster such a meme by greatly misstating the number of stars that have been searched for extraterrestrial radio signals, dramatically understating such a number, then the "we've only just begun" meme may start to sound less than honest.

On July 1, 2019 there appeared an article on the site of the SETI Institute, a leading organization in the search for extraterrestrial life.  The article was written by Seth Shostak, a senior scientist of the SETI Institute. The article reported on the failure of the Breakthrough Listen project to find radio signals from extraterrestrial civilizations.  The article was entitled, "Search for space aliens comes up empty, but extraterrestrial life could still be out there."

In the article Shostak attempts to persuade us that only about 2000 stars have been searched for extraterrestrial radio signals.  He states, "The new results from Breakthrough Listen — an examination of roughly 1,300 nearby stars — has approximately doubled the tally of reconnoitered real estate." If a search of 1300 stars had "doubled the tally of reconnoitered real estate," then it would have to be that only about 650 stars had been previously checked for extraterrestrial radio signals, and that a total of only about 2000 stars had been searched for such radio signals.   Later in the article, Shostak makes a statement that clearly teaches that the number of stars searched for extraterrestial radio signals is less than 5000.  He states, "Their long-term goal is to target a million star systems — exceeding by hundreds of times the total number of targets scrutinized by SETI since the birth of the field 60 years ago."  A million divided by 200 is 5000, so if a search for a million star systems were to exceed "by hundreds of times the total number of targets scrutinized by SETI since the birth of the field 60 years ago," it would have to have been that the number of star systems searched for extraterrestrial radio signals was 5000 or less. 

The summary numbers Shostak gave us in this article are far from true.  The actual number of star systems that have been searched for extraterrestrial signals using SETI techniques prior to 2019 is vastly in excess of 5,000.  In 2014 a paper was published with the title "SETI Observations of Exoplanets with the Allen Telescope Array."  The paper described 19,000 hours of observations of 9293 stars, searching in "multiple bands."  No extraterrestrial radio signals were found.  The paper was co-authored by Shostak himself. 

In 2016 numerous press stories reported that Shostak's SETI Institute was going to start conducting a search of 20,000 red dwarf stars to look for signs of extraterrestrial signals. This was a different set of stars than the 9293 stars searched by the previously mentioned survey.  In 2019 Shostak was quoted as saying this: 

"What would be the best strategy to find ET? We’ve been looking at a list of about 20,000 so-called red dwarf stars."

So why did Shostak tell us in his 2019 article that only about 2000 stars had been searched? The page here can be used to examine previous radio SETI searches. The page here can be used to examine previous optical SETI searches. It is clear from such pages that very many stars have been checked using SETI, many times more than Shostak indicated.  For example, the paper here discusses how optical SETI searches were made on more than 6000 stars.

Many of the SETI searches were full-sky or portion-of-the-sky surveys in which an instrument simply scans a specific fraction of the sky (or the whole sky) rather than targeting specific stars. Such searches end up being equivalent to a survey of more than 100,000 stars, often vastly more. For example, in the SETI paper here we read the following:

"These initial observations covered 1% of the sky....Using a model of ∼ 107 Sun-like stars in range (and 108 total stars in range), 1% sky coverage implies that ∼ 105 Sun-like stars—a factor of ∼ 200 more than that in the targeted search—were surveyed."

So the paper is indicating that 100,000 Sun-like stars (the same as 10Sun-like stars) were searched for optical signals from extraterrestrial civilizations, when only 1% of the sky was surveyed.  We would get much larger numbers if we calculated the number of stars that have been searched for radio signals, in surveys that used full-sky or large portion-of-the-sky surveys. As the paper here notes, "Wide-field surveys serve as a way to sample 106 - 108 more stars than pointed surveys, albeit at lesser sensitivity.”

How many stars were searched from the searches below, involving much more than 1% of the sky?

  • The SERENDIP project, surveying a large portion of the sky, the portion depicted in Figure 4 of the paper here, a project which a Sky and Telescope article tells us surveyed "many billions of Milky Way stars."
  • The Southern SERENDIP project surveying a large portion of the sky, the portion depicted in Figure 2 of the paper here.
  • The SETI project discussed here, surveying a significant portion of the sky, the portion depicted in Figure 2 of the paper here
  • The all-sky SETI survey discussed here, which operated continuously for more than four years. 
  • The two-year southern sky SETI search discussed here, which observed for 9000 hours and "covered the sky almost two times."  

It would seem that when we consider both star-specific and full-sky or portion-of-the-sky searches, the number of stars that have been searched for extraterrestrial signals before 2019 is more than 100  times greater than the number suggested by Shostak in his July 1, 2019 article.  If we extrapolate from the SETI paper quotation quoted above, in which 1% sky coverage is equated with 100,000 sun-like stars, it would seem that SETI searches have actually checked millions of stars,  at least hundreds of times more than the number suggested by Shostak. So it is not at all true that SETI searches have "only just begun," or that only a small number of stars have been checked. 

Strangely, Shostak's claims in his July 1, 2019 article are very inconsistent with a 2017 written testimony he submitted to the United States Congress. In that testimony he stated the following: 

"To put that in context, if we conjecture that there are 100 thousand signaling societies in our galaxy, then we will have to scrutinize roughly one million star systems before detecting a transmission. This is approximately ten times the total sample of all SETI experiments undertaken since 1960."

Since a million divided by 10 is 100,000, Shostak here states that about 100,000 star systems have been searched by SETI, which is a number 50 times greater than the number he gives in his July 1, 2019 article.  Even that 100,000 figure is an understatement, for the portion-of-the-sky and full-sky surveys had a combined sample size of millions of stars, in the sense that they would have detected a strong consistent radio signal from any of millions of stars.

In his written testimony to Congress, Shostak failed to present a convincing case for thinking that SETI efforts will succeed, and he failed to clearly describe any great benefit that would come if extraterrestrial radio signals were to be found. But he does reveal a little about theological motivations of SETI.  He makes it clear in his first paragraph that SETI is about proving that "biology is not some sort of miracle."  

Given its very mysterious workings and its complexity far greater than the complexity of any machines humans can construct, I can understand why some people might fear that biology is some sort of miracle;  and I can understand why people might spend decades trying to remove their fear about this matter. But I don't understand why anyone would think that finding a second example of biology (on some distant planet) would prove that biology is not some sort of miracle. If a man points towards a mountain top, and the mountain top rises way up in the air, that would presumbably be a miracle. If the man does the same thing with a second mountain top, causing that mountain top to also rise way up in the air, this would seem to be two miracles, and not at all prove that the first case was not a miracle. So given its gigantic complexity and mysterious workings, why would we suddenly conclude that life is not a miracle merely because we observed it in a second very distant place? 

In his testimony to Congress, Shostak claimed that finding some extraterrestrial intelligence would prove that life is "commonplace" and "ubiquitous," but also states that "whatever intelligence is found will likely be hundreds of lightyears distant or more."  Why would we conclude that life is "commonplace" or "ubiquitous" because we had merely found one type of life hundreds of light-years distant? There are thousands of sun-like stars in a cubic volume of a few hundred light-years, so finding one radio signal hundreds of light-years distant would not actually prove that life existed on more than one solar system in a thousand.