Will an astronomical anomaly challenge the idea of scientific revolutions?

Hindustan Times

3 days ago

Before the revolution triggered by Nicolaus Copernicus, a 16th-century cleric, the Earth was the unmoving centre of the cosmos. Afterwards, it was one of a family of planets swinging through space. Before the work of Antoine Lavoisier, an 18th-century nobleman, chemists had no notion of 'oxygen', 'carbon' and the like; afterwards they could not understand the contents of their alembics without them.
Such examples are at the heart of the idea, put forward in the 1960s by Thomas Kuhn, of the paradigm shift. Such shifts, he argued, did not just involve a new theory explaining the world better than an old one; they required a change in the sort of entities the world was thought to be made up of. In a way that seems almost self-exemplifying, the idea provided a new way of looking at science itself: not as one thing, but two. In the 'normal' phase scientists applied their physical and conceptual tools to problems the scope of which was pretty well understood; in revolutionary phases, paradigms shifted.
Normal didn't mean dull or unimportant. When, in the 1980s, American astronomers made the case for the Hubble Space Telescope, then the costliest scientific instrument in history, none of its goals mattered more than what seemed a perfect example of normal science: nailing down the value of the constant (also named after Edwin Hubble, an astronomer) which says how fast the universe is expanding.
The Hubble did this very well. The difficulty, as our Science section reports, is that since its launch it has become possible to estimate the Hubble constant on the basis of background radiation from all over the sky, rather than distances to individual objects. And these new estimates are significantly lower. The seemingly unbridgeable divide between the approaches has become known as the Hubble tension.
To those who know their Kuhn this looks like the sort of anomaly that might precede some new paradigm shift. The possibility is tantalising. The conceptual usefulness of paradigm shifts has been much debated, as indeed has their existence. The concept is horribly overused. (A new paradigm for vegan cosmetics!) Yet the notion of a fresh worldview remains dramatic and beguiling, and the romance only increases when it applies on a cosmic, but reassuringly inconsequential scale. (A paradigm shift in financial markets might be far more practically important.)
The problem is that, as Kuhn noted, you can judge these things only in retrospect. The sort of anomaly that is recast and solved by a paradigm shift is not in principle distinguishable from a 'normal' problem which has not yet been solved.
The paradigms in which normal science is done are, like the fabric of the universe, somewhat stretchy; new ideas, sometimes quite big ones, can be incorporated without wholesale change. And some suspect that science's capacity to adapt itself in this way has increased since the days of Kuhn's examples. It is far more institutionalised and regimented today, and that may provide a stability, even a rigidity, to its worldviews.
This need not be a bad thing. Paradigm shifts are not necessary for technological improvement. But it is hard not to think that, if their age has gone, then so has some of science's thrill—and hard not to want the Hubble tension to demonstrate that paradigms can still be pulled apart.
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