June 24, 2022


Armchair science (Dan Falkis, 6/23/22, Aeon)

There are - allegedly - occasions when we come to understand something about the world via a peculiar kind of experiment that takes place only in the mind. Thought experiments, as they're known, are an exercise of pure imagination. We think about some particular arrangement of things in the world, and then work out what the consequences would be. In doing so, we seem to learn something about the laws of nature.

Thought experiments have played a crucial role in the history of physics. Galileo was the first great master of the thought experiment; Albert Einstein was another. In one of his most celebrated thought experiments, Galileo shows that heavy objects and small objects must fall at the same rate. On another occasion - building on the ship's mast argument - he deduces the equivalence of reference frames moving at a constant speed with respect to one another (what we now call Galilean relativity), a cornerstone of classical physics.

Einstein, too, was adept at performing such imaginative feats in his head. As a young man, he imagined what it would be like to run alongside a beam of light, and it led him to special relativity. Later, he imagined a falling man, and realised that in freefall one doesn't feel one's own weight; from this insight, he concluded that acceleration was indistinguishable from the tug of gravity. This second breakthrough became known as the 'principle of equivalence', and led Einstein to his greatest triumph, the general theory of relativity.

What these examples have in common is that knowledge seems to arise from within the mind, rather than from some external source. They require no laboratory, no grant proposal, no actual doing of ... anything. When we perform a thought experiment, we learn, it would seem, by pure introspection. 'Seem' is perhaps the key word. Whether thought experiments actually do present a challenge to empiricism is hotly contested.

The universe is homocentric. 

Posted by at June 24, 2022 7:05 AM