(This is Part 1 in a series.)
In 1962 the historian of science Thomas Kuhn published
The Structure of Scientific Revolutions. His thesis was that science proceeds in a given field by first developing aparadigm—a successful set of ideas which is able to explain most of the available observations in that field.
This successful paradigm is then extended in what Kuhn called "normal science," where scientists work within the structure of the paradigm to develop and strengthen it, a process which he called "solving puzzles."
But after a period of time and a string of successes, each paradigm eventually begins to run into problems. As experiments in the field become more refined, anomalies begin cropping up between observation and theory. The paradigm is still dominating its field, but eventually the anomalies develop into a full-blown crisis.
Somewhere in the crisis, a new paradigm emerges which explains the anomalies that the older paradigm could not, or explains them in a way which is simpler or more elegant. The new paradigm, though considered a calamity within the established structure, eventually brings about a shift in humankind's view of its world.
To begin, let's look at the Copernican Revolution:
The Egyptian astronomer Ptolemy postulated in 150 AD that the earth was the center of the universe and that everything revolved around it, including a planet called "the sun." This seemed to accord with observation and was a successful paradigm in explaining heavenly events for over a thousand years.
But as time went on, and astronomical observations became more precise, problems cropped up in the Ptolemaic Theory. These discrepancies in observation were solved by invoking a concept of epicycles upon epicycles, where circles of planetary revolution were enhanced by smaller circles riding upon the larger ones.
But as more time went on and more epicircles were added to meet new observations, the theory became more and more cumbersome. It began to resemble a vast Rube Goldberg machine.
By the early 16th century these discrepancies between theory and observation had reached a critical point. Astronomy was in crisis as astronomers recognized that a new theory was needed. But what was it to be?
Nicolas Copernicus in 1530 gave to the world De Revolutionibus. In it he proposed the radical theory that the earth revolved around the sun once a year and spun on its axis once a day.
Copernicus, and later Kepler, were able to show that this concept could explain the various astronomical observations with greater power, precision and simplicity than the old paradigm.
But to the mass of humankind, the Copernican Theory represented a profound threat to humankind's vision of itself as the center of the universe. Moreover, Copernicus' vision meant that the universe was frightenly larger than had been imagined—a solar system with planets revolving around a sun.
Indeed, as Goethe said, the Copernican Theory, while considered a catastrophe in its time, yet "authorized and demanded a freedom of view and greatness of thought so far unknown, indeed not even dreamed of."
Let's look at another successful paradigm, which can be called the Theory of Grand Design. This paradigm, successful for over two thousand years, held that God designed all animal and plant species in great detail a few thousand years ago.
But eventually problems began to crop up in this paradigm. For one thing, there was increasing evidence in the fossil record of some sort of evolution of species. Moreover, there was increasing evidence that the earth may have existed for millions of years. By the 19th century these anomalies had developed into a crisis.
Then, in 1859, Charles Darwin published On The Origin Of Species. This new and radical paradigm proposed that species evolved through natural selection and that mankind itself had evolved from ape-like ancestors.
Once again this represented a cataclism to human perception, because it removed humanity another step from the central place—in its own mind—that it occupied in the grand scheme of things. But the Theory of Evolution, as it came to be known, also vastly broadened humanity's vistas of evolutionary time.
A final example of a successful paradigm is Isaac Newton's Theory of Gravity, published in Newton's
Principia in 1687. In this paradigm, gravity was a force which acted through space in a straight line from one mass to another. For two centuries Newton's paradigm had held sway, the most successful theory in history.
But by the mid-19th century, serious questions were arising. How did this force of gravity operate? How did gravity manage to exert its influence over vast celestial distances? Newton's theory had no explanation, and by 1900 physics was in crisis over this and other matters.
Then Albert Einstein proposed in 1915 in The General Theory of Relativity that space itself became curved in the presence of matter.
This new paradigm could explain how large bodies like the sun exerted their influence, by heavily curving the space around them—so that a planet like the Earth was simply following the path of least resistance through space as it orbited around the sun.
According to Einstein's theory, light itself would be bent slightly as it passed close to a massive body such as a star. To test this prediction, Arthur Eddington and other scientists, using very subtle measurements made during an eclipse of the sun, measured the curvature of light.
Their result, achieved on May 29, 1919, demonstrated that space was indeed curved near massive stars and that this was "gravity." This radical outcome, published the next morning by newspapers around the globe, made Einstein world-famous overnight.
The idea that space itself could be curved was a seismic shock to the public, and yet this shock helped to prepare the way for tremendous accomplishments in physics and astronomy over the next century.
(This is the end of Part 1. Go to Part 2.)
—jim sloman, 2.14.04 for Sep 23
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