In 1960, Drake organizes the first SETI conference, and came up with the now-famous Drake equation: N=N*fp ne fl fi fc fL [where N is the number of stars in the Milky Way galaxy; fp is the fraction with planets; ne is the number of planets per star capable of supporting life; fl is the fraction of planets where life evolves; fi is the fraction where intelligent life evolves; and fc is the fraction that communicates; and fL is the fraction of the planet's life during which the communicating civilizations live.]
This serious-looking equation gave SETI a serious footing as a legitimate intellectual inquiry. The problem, of course, is that none of the terms can be known, and most cannot even be estimated. The only way to work the equation is to fill in with guesses. And guesses-just so we're clear-are merely expressions of prejudice.
Nor can there be "informed guesses." If you need to state how many planets with life choose to communicate, there is simply no way to make an informed guess. It's simply prejudice.
As a result, the Drake equation can have any value from "billions and billions" to zero. An expression that can mean anything means nothing. Speaking precisely, the Drake equation is literally meaningless, and has nothing to do with science.
I take the hard view that science involves the creation of testable hypotheses. The Drake equation cannot be tested and therefore SETI is not science. SETI is unquestionably a religion.
Faith is defined as the firm belief in something for which there is no proof. The belief that the Koran is the word of God is a matter of faith. The belief that God created the universe in seven days is a matter of faith. The belief that there are other life forms in the universe is a matter of faith. There is not a single shred of evidence for any other life forms, and in forty years of searching, none has been discovered.There is absolutely no evidentiary reason to maintain this belief. SETI is a religion.
One way to chart the cooling of enthusiasm is to review popular works on the subject. In 1964, at the height of SETI enthusiasm, Walter Sullivan of the NY Times wrote an exciting book about life in the universe entitled WE ARE NOT ALONE. By 1995, when Paul Davis wrote a book on the same subject, he titled it ARE WE ALONE? ( Since 1981, there have in fact been four books titled ARE WE ALONE.) More recently we have seen the rise of the so-called "Rare Earth" theory which suggests that we may, in fact, be all alone.
Again, there is no evidence either way.
Back in the sixties, SETI had its critics, although not among astrophysicists and astronomers. The biologists and paleontologists were harshest. George Gaylord Simpson of Harvard sneered that SETI was a "study without a subject," and it remains so to the present day. But scientists in general have been indulgent toward SETI, viewing it either with bemused tolerance, or with indifference. After all, what's the big deal? It's kind of fun. If people want to look, let them. Only a curmudgeon would speak harshly of SETI. It wasn't worth the bother.
And of course, it is true that untestable theories may have heuristic value. Of course, extraterrestrials are a good way to teach science to kids. But that does not relieve us of the obligation to see the Drake equation clearly for what it is-pure speculation in quasi-scientific trappings.
The fact that the Drake equation was not greeted with screams of outrage-similar to the screams of outrage that greet each Creationist new claim, for example-meant that now there was a crack in the door, a loosening of the definition of what constituted legitimate scientific procedure. And soon enough, pernicious garbage began to squeeze through the cracks.
Now let's jump ahead a decade to the 1970s, and Nuclear Winter. In 1975, the National Academy of Sciences reported on "Long-Term Worldwide Effects of Multiple Nuclear Weapons Detonations" but the report estimated the effect of dust from nuclear blasts to be relatively minor.
In 1979, the Office of Technology Assessment issued a report on "The Effects of Nuclear War" and stated that nuclear war could perhaps produce irreversible adverse consequences on the environment. However, because the scientific processes involved were poorly understood, the report stated it was not possible to estimate the probable magnitude of such damage.
Three years later, in 1982, the Swedish Academy of Sciences commissioned a report entitled "The Atmosphere after a Nuclear War: Twilight at Noon," which attempted to quantify the effect of smoke from burning forests and cities. The authors speculated that there would be so much smoke that a large cloud over the northern hemisphere would reduce incoming sunlight below the level required for photosynthesis, and that this would last for weeks or even longer.
The following year, five scientists including Richard Turco and Carl Sagan published a paper in Science called "Nuclear Winter: Global Consequences of Multiple Nuclear Explosions." This was the so-called TTAPS report, which attempted to quantify more rigorously the atmospheric effects, with the added credibility to be gained from an actual computer model of climate.
At the heart of the TTAPS undertaking was another equation, never specifically expressed, but one that could be paraphrased as follows:
Ds = Wn Ws Wh Tf Tb Pt Pr Pe etc (The amount of tropospheric dust = # warheads x size warheads x warhead detonation height x flammability of targets x Target burn duration x Particles entering the Troposphere x Particle reflectivity x Particle endurance, and so on.)
The similarity to the Drake equation is striking. As with the Drake equation, none of the variables can be determined. None at all. The TTAPS study addressed this problem in part by mapping out different wartime scenarios and assigning numbers to some of the variables, but even so, the remaining variables were-and are-simply unknowable. Nobody knows how much smoke will be generated when cities burn, creating particles of what kind, and for how long. No one knows the effect of local weather conditions on the amount of particles that will be injected into the troposphere. No one knows how long the particles will remain in the troposphere. And so on.
And remember, this is only four years after the OTA study concluded that the underlying scientific processes were so poorly known that no estimates could be reliably made.
Nevertheless, the TTAPS study not only made those estimates, but concluded they were catastrophic. According to Sagan and his coworkers, even a limited 5,000 megaton nuclear exchange would cause a global temperature drop of more than 35 degrees Centigrade, and this change would last for three months.
The greatest volcanic eruptions that we know of changed world temperatures somewhere between .5 and 2 degrees Centigrade. Ice ages changed global temperatures by 10 degrees. Here we have an estimated change three times greater than any ice age.
One might expect it to be the subject of some dispute. But Sagan and his coworkers were prepared, for nuclear winter was from the outset the subject of a well-orchestrated media campaign. The first announcement of nuclear winter appeared in an article by Sagan in the Sunday supplement, Parade. The very next day, a highly-publicized, high-profile conference on the long-term consequences of nuclear war was held in Washington, chaired by Carl Sagan and Paul Ehrlich, the most famous and media-savvy scientists of their generation.
Sagan appeared on the Johnny Carson show 40 times. Ehrlich was on 25 times. Following the conference, there were press conferences, meetings with congressmen, and so on. The formal papers in Science came months later.
This is not the way science is done, it is the way products are sold. The real nature of the conference is indicated by these artists' renderings of the effect of nuclear winter. (Not Shown)
I cannot help but quote the caption for figure 5: "Shown here is a tranquil scene in the north woods. A beaver has just completed its dam, two black bears forage for food, a swallow-tailed butterfly flutters in the foreground, a loon swims quietly by, and a kingfisher searches for a tasty fish." Hard science if ever there was.
At the conference in Washington, during the question period, Ehrlich was reminded that after Hiroshima and Nagasaki, scientists were quoted as saying nothing would grow there for 75 years, but in fact melons were growing the next year. So, he was asked, how accurate were these findings now?
Ehrlich answered by saying "I think they are extremely robust. Scientists may have made statements like that, although I cannot imagine what their basis would have been, even with the state of science at that time, but scientists are always making absurd statements, individually, in various places. What we are doing here, however, is presenting a consensus of a very large group of scientists"
I want to pause here and talk about this notion of consensus, and the rise of what has been called consensus science. I regard consensus science as an extremely pernicious development that ought to be stopped cold in its tracks. Historically, the claim of consensus has been the first refuge of scoundrels; it is a way to avoid debate by claiming that the matter is already settled. Whenever you hear the consensus of scientists agrees on something or other, reach for your wallet, because you're being had.
Let's be clear: the work of science has nothing whatever to do with consensus. Consensus is the business of politics. Science, on the contrary, requires only one investigator who happens to be right, which means that he or she has results that are verifiable by reference to the real world.
In science consensus is irrelevant. What is relevant is reproducible results. The greatest scientists in history are great precisely because they broke with the consensus. There is no such thing as consensus science. If it's consensus, it isn't science. If it's science, it isn't consensus. Period.
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But back to our main subject. What I have been suggesting to you is that nuclear winter was a meaningless formula, tricked out with bad science, for policy ends. It was political from the beginning, promoted in a well-orchestrated media campaign that had to be planned weeks or months in advance.
Further evidence of the political nature of the whole project can be found in the response to criticism. Although Richard Feynman was characteristically blunt, saying, "I really don't think these guys know what they're talking about," other prominent scientists were noticeably reticent. Freeman Dyson was quoted as saying "It's an absolutely atrocious piece of science but who wants to be accused of being in favor of nuclear war?" And Victor Weisskopf said, "The science is terrible but---perhaps the psychology is good.
The nuclear winter team followed up the publication of such comments with letters to the editors denying that these statements were ever made, though the scientists since then have subsequently confirmed their views. At the time, there was a concerted desire on the part of lots of people to avoid nuclear war. If nuclear winter looked awful, why investigate too closely? Who wanted to disagree? Only people like Edward Teller, the "father of the H bomb."
Teller said, "While it is generally recognized that details are still uncertain and deserve much more study, Dr. Sagan nevertheless has taken the position that the whole scenario is so robust that there can be little doubt about its main conclusions."
Yet for most people, the fact that nuclear winter was a scenario riddled with uncertainties did not seem to be relevant. I say it is hugely relevant. Once you abandon strict adherence to what science tells us, once you start arranging the truth in a press conference, then anything is possible.
In one context, maybe you will get some mobilization against nuclear war. But in another context, you get Lysenkoism. In another, you get Nazi euthanasia. The danger is always there, if you subvert science to political ends.
That is why it is so important for the future of science that the line between what science can say with certainty, and what it cannot, be drawn clearly-and defended.
What happened to Nuclear Winter? As the media glare faded, its robust scenario appeared less persuasive; John Maddox, editor of Nature, repeatedly criticized its claims; within a year, Stephen Schneider, one of the leading figures in the climate model, began to speak of "nuclear autumn." It just didn't have the same ring.
A final media embarrassment came in 1991, when Carl Sagan predicted on Nightline that Kuwaiti oil fires would produce a nuclear winter effect, causing a "year without a summer," and endangering crops around the world. Sagan stressed this outcome was so likely that "it should affect the war plans." None of it happened.
What, then, can we say were the lessons of Nuclear Winter? I believe the lesson was that with a catchy name, a strong policy position and an aggressive media campaign, nobody will dare to criticize the science, and in short order, a terminally weak thesis will be established as fact.