Hitting the Books: How 20th century science unmade Newton's universe
Mercury's orbit defies Newtonian physics, so why shouldn't the rest of creation?
Science is the reason you aren't reading this by firelight nestled cozily under a rock somewhere however, its practice significantly predates its formalization by Galileo in the 16th century. Among its earliest adherents — even before pioneering efforts of Aristotle — was Animaxander, the Greek philosopher credited with first arguing that the Earth exists within a void, not atop a giant turtle shell. His other revolutionary notions include, "hey, maybe animals evolved from other, earlier animals?" and "the gods aren't angry, that's just thunder."
While Animaxander isn't often mentioned alongside the later greats of Greek philosophy, his influence on the scientific method cannot be denied, argues NYT bestselling author, Carlo Rovelli, in his latest book, Animaxander and the Birth of Science, out now from Riverhead Books. In in, Rovelli celebrates Animaxander, not necessarily for his scientific acumen but for his radical scientific thinking — specifically his talent for shrugging off conventional notion to glimpse at the physical underpinnings of the natural world. In the excerpt below, Rovelli, whom astute readers will remember from last year's There Are Places in the World Where Rules Are Less Important than Kindness, illustrates how even the works of intellectual titans like Einstein and Heisenberg can and inevitably are found lacking in their explanation of natural phenomena — in just the same way that those works themselves decimated the collective understanding of cosmological law under 19th century Newtonian physics.
Excerpted from Animaxander and the Birth of Science. Copyright © 2023 by Carlo Rovelli. Excerpted by permission of Riverhead, an imprint and division of Penguin Random House LLC, New York. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Did science begin with Anaximander? The question is poorly put. It depends on what we mean by “science,” a generic term. Depending on whether we give it a broad or a narrow meaning, we can say that science began with Newton, Galileo, Archimedes, Hipparchus, Hippocrates, Pythagoras, or Anaximander — or with an astronomer in Babylonia whose name we don’t know, or with the first primate who managed to teach her offspring what she herself had learned, or with Eve, as in the quotation that opens this chapter. Historically or symbolically, each of these moments marks humanity’s acquisition of a new, crucial tool for the growth of knowledge.
If by “science” we mean research based on systematic experimental activities, then it began more or less with Galileo. If we mean a collection of quantitative observations and theoretical/mathematical models that can order these observations and give accurate predictions, then the astronomy of Hipparchus and Ptolemy is science. Emphasizing one particular starting point, as I have done with Anaximander, means focusing on a specific aspect of the way we acquire knowledge. It means highlighting specific characteristics of science and thus, implicitly, reflecting on what science is, what the search for knowledge is, and how it works.
What is scientific thinking? What are its limits? What is the reason for its strength? What does it really teach us? What are its characteristics, and how does it compare with other forms of knowledge?
These questions shaped my reflections on Anaximander in preceding chapters. In discussing how Anaximander paved the way for scientific knowledge, I highlighted a certain number of aspects of science itself. Now I shall make these observations more explicit.
The Crumbling of Nineteenth Century Illusions
A lively debate on the nature of scientific knowledge has taken place during the last century. The work of philosophers of science such as Carnap and Bachelard, Popper and Kuhn, Feyerabend, Lakatos, Quine, van Fraassen, and many others has transformed our understanding of what constitutes scientific activity. To some extent, this reflection was a reaction to a shock: the unexpected collapse of Newtonian physics at the beginning of the twentieth century.
In the nineteenth century, a common joke was that Isaac New‐ ton had been not only one of the most intelligent men in human history, but also the luckiest, because there is only one collection of fundamental natural laws, and Newton had had the good fortune to be the one to discover them. Today we can’t help but smile at this notion, because it reveals a serious epistemological error on the part of nineteenth-century thinkers: the idea that good scientific theories are definitive and remain valid until the end of time.
The twentieth century swept away this facile illusion. Highly accurate experiments showed that Newton’s theory is mistaken in a very precise sense. The planet Mercury, for example, does not move following Newtonian laws. Albert Einstein, Werner Heisenberg, and their colleagues discovered a new collection of fundamental laws — general relativity and quantum mechanics — that replace Newton’s laws and work well in the domains where Newton’s theory breaks down, such as accounting for Mercury’s orbit, or the behavior of electrons in atoms.
Once burned, twice shy: few people today believe that we now possess definitive scientific laws. It is generally expected that one day Einstein’s and Heisenberg’s laws will show their limits as well, and will be replaced by better ones. In fact, the limits of Einstein’s and Heisenberg’s theories are already emerging. There are subtle incompatibilities between Einstein’s theory and Heisenberg’s, which make it unreasonable to suppose that we have identified the final, definitive laws of the universe. As a result, research goes on. My own work in theoretical physics is precisely the search for laws that might combine these two theories.
Now, the essential point here is that Einstein’s and Heisenberg’s theories are not minor corrections to Newton’s. The differences go far beyond an adjusted equation, a tidying up, the addition or replacement of a formula. Rather, these new theories constitute a radical rethinking of the world. Newton saw the world as a vast empty space where “particles” move about like pebbles. Einstein understands that such supposedly empty space is in fact a kind of storm-tossed sea. It can fold in on itself, curve, and even (in the case of black holes) shatter. No one had seriously contemplated this possibility before. For his part, Heisenberg understands that Newton’s “particles” are not particles at all but bizarre hybrids of particles and waves that run over Faraday lines’ webs. In short, over the course of the twentieth century, the world was found to be profoundly different from the way Newton imagined it.
On the one hand, these discoveries confirmed the cognitive strength of science. Like Newton’s and Maxwell’s theories in their day, these discoveries led quickly to an astonishing development of new technologies that once again radically changed human society. The insights of Faraday and Maxwell brought about radio and communications technology. Einstein’s and Heisenberg’s led to computers, information technology, atomic energy, and countless other technological advances that have changed our lives.
But on the other hand, the realization that Newton’s picture of the world was false is disconcerting. After Newton, we thought we had understood once and for all the basic structure and functioning of the physical world. We were wrong. The theories of Einstein and Heisenberg themselves will one day likely be proved false. Does this mean that the understanding of the world offered by science cannot be trusted, not even for our best science? What, then, do we really know about the world? What does science teach us about the world?