Freeman Dyson is one of the grand old men of physics, who at the age of 88 continues to instruct us with his occasional essays in the New York Review of Books. (I've been catching up on back issues I missed while on the island.)
In a spring issue, Dyson addresses the question of real science versus fringe science. What is it, for example, that distinguishes Einstein's theory of general relativity from Immanuel's Velikovsky's World's In Collision? Both theories sprang from the heads of bright fellows, with only modest observational foundations. Both theories caught the public imagination.
As it turns out, Dyson knew and admired Velikovsky, and of course he was well-familiar with general relativity. And he is not unsympathetic to Velikovsky's wild conjectures about colliding planets. "We gain knowledge of our place in the universe not only from science but also from history, art, and literature," he says, and counts Velikovsky as something of an artist and poet, rather along the lines of William Blake. Fringe science, like that of Velikovsky, is "what happens when imagination loses touch with observation," writes Dyson. And adds: "Imagination by itself can still enlarge our vision when observation fails.
In this, I think Dyson is being too generous to Velikovsky. whose far-fetched –- and immensely popular -- theories seem to me more in line with, say, the Left Behind books of LaHaye and Jenkins. We are not talking about losing touch with observation, but of never having touched it at all.
A more interesting question might be: What distinguishes string theory from, say, the morphological resonances of Rupert Sheldrake. Neither theory has much -– anything? – in the way of observational support, but string theory gets a passes as real science, while Sheldrake is written off by the establishment as a crackpot. Here, I think, Dyson could have been more helpful. "The glory of science is to imagine more than we can prove," he writes, which might apply as much to Sheldrake as to the string theorists.
The relevant distinction, I think, is this: Although string theory reaches out into the far-fetched unknown, it maintains mathematical roots in the soil of observational science.
Still, as Dyson observes: "The fringe of physics is not a sharp boundary with truth on one side and fantasy on the other." Ultimately, only quantitative observation will distinguish science from pseudoscience.
Someone once quoted Shakespeare to the philosopher W. V. O. Quine: "There are more things in heaven and earth, Horatio, than are dreamed of in your philosophy." To which Quine allegedly replied: "Possibly, but my concern is that there not be more things in my philosophy than there are in heaven and earth."