David Stevenson has a nice Commentary in Physics Today:
He argues in defense of “crazy” ideas in science. He categorized three kind of “crazy”:
The First Kind is simple crackpottery: people who don’t know enough science to articulate a real scientific idea, and do not understand its interconnectedness well enough to distinguish outré ideas from nonsense ones. He says this is the most common and least interesting (and he’s right, except as a study in sociology)
The Second Kind is when good scientists take a fresh, naïve look at a new field. He writes:
Inevitably, such excursions can look like the actions of a dilettante…One is then accused of speculation. I occasionally sense from colleagues some disdain for scientific speculation, perhaps because it is cheap: It seems to require relatively little effort and commitment.
He argues that hard, serious speculation is rare and important. This is certainly something I’ve tried to engage in. My excursions into lunar geology theory, the Faint Young Sun problem, and even SETI (at first) were certainly in this category. Indeed, the reactions I got to our lunar highlands work from the lunar science community ranged from the pleasant to the snide (Dave himself was polite, but dismissive—though, after reading this I wonder if I misread him. Caltech GPS was certainly the most receptive audience I found.).
Physicists are prone to this sort of work (consider Richard Muller’s forays into climate science (and borderline denialism)) to the point of cliché (one of my favorite SMBC comics), and SETI seems to be a favorite destination for dilettantes from all fields.
The Third Kind are when established leaders in their fields upset the table with entirely new perspectives. One occasionally sees cals for such ideas: Lindy Elkins-Tanton acknowledged the need for new ideas in lunar formation theory in Nature, and Michael Inzlicht in psychology has done serious soul searching, wondering if his career, indeed much of his field, is based on bad statistics. But these ideas are not always invited or even welcome; Stevenson’s examples are Hoyle’s Black Cloud and steady-state cosmology, and the idea of emergent gravity. He finishes with a quote from Neils Bohr to Wolfgang Pauli: “We are all agreed that your theory is crazy. The question which divides us is whether it is crazy enough to have a chance of being correct.”
Stevenson briefly mentions a “portfolio” of ideas, and this brings me to one of my favorite papers, Avi Loeb’s banquet lecture (here at Penn State!) about how young scientists should divide their research time. He argues for some fraction of time to be spent on “venture capital”, analogous to spending some of your financial portfolio on high-risk, high-reward investments. (Avi may have been inspired by Eric Weinstein’s lecture on the topic, h/t Michael Neilson for pointing me to it) Avi acknowledges that there is actually a lot of acceptance for work on outré topics, but argues that the natural conservatism of the Academy and science tends to favor no more than 5% of one’s efforts there. He argues it should be more like 20%.
I think between 5-20% is right, in an average sense. So some scientists should spend 100% of their effort on safe “bonds”, others a lot more on venture capital (my last few years have involved much more SETI than I had planned for), but if as a whole we’re working between 5-20% of the time on Second and Third Kind speculation, I think we’ll do well.
I use “outré” above instead of “crazy” (and I put the latter in scare quotes) because the latter is a slur for people with mental health issues. I appreciate it’s often not meant that way, but I think society is slowly realizing how common mental illness is, how badly and unjustly it is stigmatized, and how casual uses of terms like “crazy” to mean “unexpected” or “weirdly different” reinforce that stigma. Also, “crazy” isn’t even the right word here—by using it, Dave is facetiously implying that one would have to be mentally ill to have come up with the idea, but all he needs to make his point is to say that it’s nonobvious, very clever, and outside the normal thought process—outré.