There is nothing like a “close encounter of the asteroid kind” to captivate the public. The resulting effect is what yields profit for Hollywood studios that make movies of the sort where brave Americans take a space ship to an interloping rock, and plant explosives to blow the thing up just seconds before it reaches dear old Earth. (At least with the old Star Trek series the crew on such death-defying missions was international, if not the Captain.) It is part of why we find it easy to neglect planning for less exotic natural disasters, such as the destruction in Russia caused by a meteor the other day (granted that that one was both big and hard to anticipate).

Stories for another day, those. Here I want to focus on another aspect of the fascination, and one that has been resurrected in recent media coverage such as WaPo’s of the flyby yesterday of asteroid 2012 DA214: the disappearance of the dinosaurs.

In 1980 the Nobel Laureate physicist Luis Alvarez, his geologist son Walter, and some others announced that there was a high concentration of the element Iridium, rare on earth but plentiful in celestial bodies like meteorites and asteroids, at the boundary between the Cretaceous and Paleogene geological periods in an area of central Italy, which boundary is precisely the time when some paleontologists believed the dinosaurs went extinct. The natural inference from this discovery, suitably buttressed by some peripheral considerations that need not detain us, was that an asteroid hit the earth at that time, some 65 million years ago, in a catastrophic collision that wiped out the giant reptiles and a good deal else. The elder Alvarez then ran with this hypothesis in a big way.

Now Alvarez was a big shot well before 1980, and even before his Nobel in 1968. I was familiar with his presence as a graduate student working at Berkeley’s Lawrence Radiation Laboratory in the late 1950s, where he was a leading figure, indeed, a person with a reputation in the back corridors as an “operator.” He led the group of physicists associated with the 72 inch liquid hydrogen bubble chamber, the sexiest of elementary particle detectors of the era, which leadership is what would get him (never mind the other physicists) his Nobel. That is to say, he was a pioneer in the development of Big Physics, where experiments are now carried out by dozens of people (so many that sometimes the Physical Review articles that report their results list their names in a footnote rather than in the byline).

I worked in the Lofgren group, which was responsible for operating the lab’s then principal atom smasher, the Bevatron machine (pictures), which supplied beams of particles for the benefit of the bubble chamber and the apparati of other groups. My mentors were William Wenzel and Bruce Cork, who had recently been part of the team that isolated the antineutron, and I also got to work with the eventual Nobel winner James Cronin for a time, while he was visiting from Princeton. Apart from physics proper, in the area of instrumentation we worked on developing the elementary particle detection device called the spark chamber, and constructed some of the first of such devices.

I mention this especially because there was a marked contrast at the “Radlab” between the cultures of the Alvarez and Lofgren groups. (The lab also had the Moyer group, which was closer to ours in mode of operation, and there may have been others that I don’t remember.) This contrast was reflected in (or was caused by?) the respective instrumentations that they worked with. The 72 inch chamber was an enormously complex device that required engineers and specialized technicians to actually operate. The first spark chambers, including ours, were largely constructed and operated by physicists themselves, physicists who were pretty much old-school “shoestring and sealing wax types,” who built their own electronic circuits, and who saw the spark chamber as a natural development from the rather crude scintillation counter electronic detection device. (On one occasion I saw Bill Wenzel with a soldering iron in one hand and a string of lead solder in the other, his eye on an oscilloscope to check the signal, risking a severe shock by repairing a circuit with the power still on.) Very much non-Big Physics.

In passing, for a time some continued to rebel against Big Physics, or at least to lament the passing of the Little variety. (I can’t find a reference to it, but I recall reading that Cronin’s co-Nobel winner Val Fitch — who had a reputation as a crack electronics technician — once worried about “what will happen to the professor and his four graduate students.”) However, granted that I am now out of touch, as far as I know any such movement is now dead.

Now back to cataclysmic collisions. Here I have to bring in another actor in the drama, Immanuel Velikovsky. In 1950 he published a book entitled Worlds in Collision, which popularized the idea of “catastrophism” as a significant factor in geological history. He did not mention dinosaurs, nor even asteroids, but spoke of the planets themselves as coming into close enough contact to cause supposed earthly events such as the Old Testament’s destruction of Sodom and Gomorrah or the Deluge. He seems to have had some theory of how electromagnetism works that allowed him to postulate that it was the mechanism that produced the encounters. To say that all this was controversial would be a gross understatement: The academic world was furious, and the book’s initial publisher Macmillan dropped out after being threatened with a boycott of its textbook line. More recently, on the fiftieth anniversary of the book’s publication, a survey of 25 leading scientists produced no one who thought Velikovsky had a “positive influence” on current catastrophist theories among scientists, and some who insisted that he had a negative influence.

Thus, although Velikovsky still has his defenders, I have no problem in believing that he was a crackpot, pure and simple. However, what the survey just mentioned shows is that his idea that Earth has experienced catastrophic celestial events was widespread at the time Alvarez put forth the asteroid-dinosaur theory. (This was once confirmed to me anecdotally: The late Joe Weber, best known for attempting to detect “gravitational waves,” told me that Velikofsky used to hang around the halls at Princeton haranguing people with his theories.)

I cannot prove to you that Alvarez was in any way motivated by what was in the air about catastrophism, and while I haven’t checked any textbooks dealing with the matter, I’m sure they have no truck with Velikofsky. But I do know that physicists misunderstand history, including that of their discipline. The “history” that they offer on the first day of a course on some subject within the field is only a hagiography of its founders. But the best examples are from the order of events in post-1960 elementary particle physics, as noted in my 2006 essay “Why I am no longer a physicist, or, one person’s perspective on the relation of humanities to science in our era.” Sometimes an error is trivial, like saying that the word “quark” comes from Joyce’s Ulysses, when it is actually from Joyce’s Finnegans Wake. But I hope it will be agreed that the issue of which came first, experiment or theory, is significant, and there is at least one case where the profession gets this wrong.

In the 1950s a candidate for a particle with the property then called “strangeness minus 3″ was possibly observed in natural radiation reaching the earth, using the very primitive detection technique of nuclear emulsion. As I reported in a seminar at the time, the fact that the observation was not definitive did not deter theoretical physicists from suggesting schemes that incorporated such a particle. Then one was definitively observed using the bubble chamber technique, whereupon it was trumpeted that one such theoretical scheme “successfully predicted” the strangeness minus 3 object. Experiment before theory became theory before experiment, and the latter sequence is what entered the textbooks. (If you pin down the physicists about this they will say that the iffy nuclear emulsion event cannot be considered the actual observation of the particle, as if that somehow negated the fact that real people developed real theoretical schemes based on the possibility that it was.)

I do not know if the Alvarez hypothesis of an asteroid killing off the dinosaurs is actually right (it remains somewhat controversial in paleontology, for all its being repeated as gospel by the Mainstream Media every time the subject comes up), and as I’ve said I do not know if he was actually thinking about Velikofsky’s theories when he had the clay sample his son had found tested for Iridium. I do doubt, however, that the asteroid-extinction theory simply fell from the sky, as it were, into his mind.

But then, I’m probably a dinosaur.

Photo by Jakub Hałun under GNU Free Documentation License