This lecture was given around about February 1998, in the Powerhouse museum in Sydney. The presenter was Frank Drake, who should need no introduction. For the ignorant among us (which is everyone occasionally) he's the originator of the Drake equation, a simplistic but seminal (my word for the week, since I looked it up in a dictionary) model for calculating the number of extraterrestrial civilisations currently extant. More on that later. I forgot to take paper and had to write my notes on the back of my own business cards and the receipt for my ticket.
After a few obligatory references to dead people from classical civilisations (OK, to Lucretius, who believed that since there was a clump of atoms "driven together" here there must also be elsewhere) Drake gave a summary of the state of our knowledge on various subjects these were:
SETI Foundation: The SETI foundation is entirely privately funded, it run on about US$4M/year. Whatever you may think of the practicality of their efforts this is chicken feed by big science standards.
Extrasolar planets: At the time he spoke there were nine known, including one around a double star (47 Ursa majoris). Most were at tiny separations (less than 0.1 AU). One was at more than 1 AU.
Miller Experiment: This was the experiment that showed that a primordial atmosphere, plus lightning, made amino acids. Drake is of the opinion that we are "very close" to proving that amino acids plus time plus stuff that was there make life. He didn't give references and semi-implied there were peer-review issues.
Evolutionary Imperative: Drake sees a pattern in the fossil record, toward increasing sophistication and increasing intelligence. He therefore sees intelligence as inevitable. He mentioned a late Cretaceous dinosaur (Saurornithoides?) with a 1 litre brain capacity in a 50 kg body. Drake believes this creature was on tenure track to become intelligent when the dinosaur-killer hit. Oddly, he referred to the dinosaurs as being "of reptilian origin".
Intrasolar Life:
Drake suggested Europa and Callisto as candidates.
Both have ice surfaces, Drake thinks Europa's is a few km thick,
Callisto's more like 200 km.
Early attempts at communication with and detection of ETs:
Arecibo: The radio telescope can be used in passive or active mode for SETI. In active mode it has a power of 1 megawatt, and an effective radiated power (power times gain) of 20 terawatts. By comparison the sun has a power of about a millionth of this second figure (and a gain of 1, of course, since it radiates isotropically). I presume these figures for the sun refer to a small bandwidth in the radio spectrum.
Arecibo replacements: The Dutch proposal for the next generation huge radio telescope is an enormous phased array. The area would be about 1 square kilometre. Since I have a professional interest in Dutch phased array antennae with a size of about 1 square metre, I found this quite impressive. The Chinese proposal, by contrast, is relatively sane: an array of thirty Arecibo-sized telescopes.
Amateur SETI: C-band 3 metre telescopes (i.e. satellite television receiver dishes) cost about US$400 each. About 4000 of them (a few day's production) would give you Arecibo-like performance. Drake thought the value lay in detecting intermittent signals, though he wasn't very enthusiastic ("not impossible" to make a contribution).
Drake Equation: Nothing new, but his current estimate is one new ET species evolving per year per galaxy. Drake would be the first to admit that most of his factors have been plucked from the land of dreams. Drake's guess of a detectable lifetime (between inventing radio and not needing it any more) is 10 000 years.
Fermi paradox: So where is everyone? Drake mentions the classics, such as that civilisations destroy themselves through nuclear war, or through pollution, or become so technically proficient that they are no longer detectable. As for space travel, he believes that "no sensible culture would travel fast through interstellar space and the stupid ones don't know how".
Moore's Law: Is working, if anything, faster than for computers. The SETI foundation's standard signal processing gadget costs US$50 (well, the first cost US$300K) and has a throughput of 0.1 terabits per second. (Naval phased array radars are measured in gigabits per second.) The foundation uses 47 of them, and will sell to anyone interested. One conclusion that could be drawn from this is that we shouldn't bother doing it until the gear gets better, needless to say Drake does not subscribe.
Arthur C. Clarke once wrote of a visit to NASA. After so many years of writing about space exploration he was looking forward greatly to meeting the people who actually did it. But the visit was made during the organisation's hesitant and cringing nadir. He was told, for instance, that the United States would now require more than ten years warning to be able to put a man on the moon, despite having done it in less time from no base at all during the 1960s. Clarke said that it was like a country priest, who'd served the catholic faith all his life with honest devotion, making the pilgrimage to the Vatican to discover that the curia was inhabited by atheists.
How much sadder to find they still believe in Santa Claus?
Let me say that I quite enjoyed the talk, and got a lot out of the review of the myriad of SETI-relevant subjects. But I was hoping for the ideas of the great man, and I didn't really get any. What am I to make of lines like "the sun is a very average star"? Am I really expected to believe a nuclear war, let alone pollution, would make the human race extinct? That it could make every intelligent species extinct? That none of Drake's billions of highly sophisticated species would decide to slowly colonise the galaxy?
I remember seeing these proposals when I was in early high school. And I remember feeling scepticism about them too. In the earlier, twitchier, less rational phase of the cold war, or during the population explosion, they would have been easy to believe, but even then they were an emotional appeal, not a rational one. Enrico Fermi's logical fortress will not fall to such weapons, and Drake does not appear to have developed anything more powerful since.