It didn’t work out
What is the use of scientific theories that aren’t right?
Our astronomer is looking into an episode in the history of his science, in which two theories were in competition. Eventually one won out, as the other didn’t fit observations. Although astronomers are generally aware that it once existed, most are fuzzy on the details, and nowadays it’s hardly more than a footnote in most textbooks. So what, in the end, is the use of a discarded theory?
[We want to emphasize that to do interdisciplinary work (such as the history of science) properly is hard. One must be proficient in both areas, history and science, and that’s not easy. Unfortunately, scientists sometimes believe that because they understand the science of a past era, they understand the history also; which often isn’t true. We have also met philosophers of science whose philosophy might be good, but whose understanding of science was deficient. So we watch our astronomer with some care when he gets going.]
Though it might surprise some non-scientists, discarded theories are many; in fact they greatly outnumber successful ones. They range from a momentary thought in a creative moment: (“what if the bright rays of Tycho crater are vanilla ice cream?”) that is immediately thrown out (“but of course ice cream would evaporate on the Moon’s surface”), to widely-accepted theories that hold the field for a long time (say, Ptolemaic cosmology). We are thinking, now, of well-worked-out explanations that were viable for a while, but never dominant and that in the end failed.
Consider one theory for the origin of the planets: rings thrown off by a shrinking Sun. Working out the details led to the mathematics of a spinning, fluid mass held together by its own gravity, a complex achievement of several great scientists. Though the reason for the development has gone away, the structure remains. Perhaps this is some justification.
More important, we think, are examples like Sir James Jeans’ theory of stellar structure (in short, something like liquid stars powered by nuclear fission). It also led to some interesting mathematics. But it stimulated the rival theory of gaseous, fusion-powered stars to develop further, to work out its defects and set out details. The challenge of an alternative kept the mainstream theory honest.
For this to happen, someone has to champion the alternative. That’s normally not a problem; humans get attached to things they spend time and effort on. But they have to continue advocacy past the point where the main theory becomes the more probable one. To clean up the its details they have to push their efforts a bit beyond the 50% point, to where it’s just a bit irrational to keep pushing. That way the cracks and we’ll-get-to-this-later parts are attended to, which is important. Even things that command widespread agreement can fall apart later on, when prodded in the right way.
It’s often not comfortable to be a critic, however vital the role may be to science. The trick is to work out the distinction between the scientific critic and the paradoxer.
