Science is (Not) Settled

How do you react when you hear (or read) “the science is settled?” Frankly, it can be a bit irritating because of who says it and why. For example, politicians use it to avoid problems. Sometimes they use it to bluster as they try to impose their will on the rest of us. Scientists may use it to brush off questions or defend their ideas from challenges. On a more positive note, sometimes we say it simply because we know the science in question is true. For example, all human beings are born with a combination of x and y chromosomes that defines their sex as male or female. We understand that part of science very well, even if it irritates people who demand political correctness.

Confidence in what we know, or at least what we think we know, has been around for as long as the human race, and so have curiosity and (often) a willingness to learn. Over 125 years ago an American physicist famously said, “While it is never safe to affirm that the future of Physical Science has no marvels in store even more astonishing than those of the past, it seems probable that most of the grand underlying principles have been firmly established.” The science was settled, or maybe not, but science is a restless enterprise. And, as it turned out, the caution about marvels lurking in the future was right on target.

Physics was settled, and then along came the theory of relativity, among other discoveries. With new theories, measurements, and findings, physics branched into particle physics, astrophysics, biophysics, and other divergent specialties. And while particle physicists use the Standard Model to explain which sub-atomic particles exist and how they relate to each other, current research sometimes reinforces the model and sometimes shakes it.

Chemistry was settled, but four new elements were added to the Periodic Table as recently as 2016. And driven by a stream of discoveries reaching back 150 years and more, chemistry branched into physical chemistry, organic chemistry, nuclear chemistry, and other divergent specialties. Ironically, the most recently discovered elements are all unstable, perhaps in some way reminding us of the dynamic nature of science.

Geology was settled, and then theories of plate tectonics shook the conventional wisdom. Geology teachers during that transition would explain about continental drift, all while glancing around the room to see if any of the old guard would challenge the new concepts. Later, a new generation of geologists began to question and refine the broad theories of plate tectonics. And so new ideas and theories continued to arise to improve (and occasionally overturn) the old ones.

Perhaps the one field of science that most often triggers the phrase, “the science is settled” is climate science. However, we don’t seem to hear that from scientists as much as we do from politicians and activists. Over the past few decades climate researchers have learned about the significance of aerosols in the atmosphere, the impacts of volcanic eruptions, the effects of cloud types and cloud cover, the variability of energy incoming from the sun, and any number of coupled feedback loops between the various processes that affect our climate. Climate scientists are still learning, which is good, but it also shows that the science is not settled.

Regardless of the topic, when you hear that “the science is settled,” it is worth asking why. Why would someone think it is settled? Why would someone make that claim? Honest inquiry leads to better science as well as better policy, and honest inquiry should not be silenced.