It’s always nice and, indeed, often very productive to hear the great physicists, the great scientific minds, expressing themselves in ordinary language terms. That gives us a bit of insight into how they truly think…and often can tell us more about such areas as psychology, or epistemology, or neuroscience than piles of research in those areas might.
Here Richard Feynman, in a video lecture, uses words that we all know..such as “ideas” or ‘psychologically” or ‘philosophy” that we might translate in formal ways into ‘paradigms” or ‘models” or something currently more fashionable.
“Suppose,” he says, “ you have two theories, theory A and theory B which look completely different psychologically They even both agree with experiment…although they sound different in their words at the beginning, they have all the same consequences It is usually easy to prove that by doing some mathematics.
“How are we going to decide which one is right? No way!” Feynman adds,… …”not by science” That is, “Because they both agree with experiment to the same extent”
Although have deeply different “ideas” behind them as we express them in words, they may be mathematically identical….and then we say that one does not know how to distinguish them
However, Feynman says, “for (what he calls) psychological reasons and in order for us to arrive at new and better theories, these two narratives, A and B, are very far from equivalent.”
There is something to which he draws our attention that is so fundamentally important to both how we understand how ‘physics” comes to “know” and accumulate its’ “knowledge’ and also we, in our everyday lives, come to “know” and accumulate our ‘knowledge”.
Why is that? “Because it is often the case that one narrative that accompanies that same mathematical formulation, either A or B, as it is expressed in its own particular wordking, gives a human, a physicist very different ideas from those derived from the other.
For example, he illustrates, “By putting the theory in a different kind of framework, he says, “ you get an idea of what to change….which will be something in theory A which talks about something …
You say to yourself, he tell us, “I’ll simply change that idea here in A”: “But,” as Feynman notes, ….”to find out ..to intuit….out what the corresponding thing you’ll have to change here, that must be changed in B, might turn out be a very, very complicated process
A simple change here in A makes maybe a very different theory than a simple change there in B would make.
Although they are identical before they change…there are certain ways of changing one which look natural in one, but which do not look natural in the other.
Beyond that and, more importantly Feynman reveals to us how science and theory depend so much on the very human matrix of mortal men and women and their so called “intuitions” which depend on expression in various “models” and are not strictly evident in the mathematics of the physical theory
“Therefore”. as he advises, “ psychologically we must keep all the different theories in our head…”Any theoretical physicist who is any good, says Feynman, knows 6 or 7 different theoretical representations for exactly the same physics…and knows that they are all equivalent and he or she knows that nobody is every going to be able to decide which one is right at that level…
But he keeps them in all his head to give him better ideas for “guessing”, as Feynman calls it. For guessing at and arriving at better theories.
It’s not just the mathematics..but the “model” which is operating it the mind of the physicist…and which those ‘ideas’ and those “words’ help to ground in his intuitions…and different words and different ideas lead to different intuitions and potentially sometime do not lead to any productive intuitions at all. And thus the theory and even its mathematical formulations are not advanced…simply because of this special interaction within the mind of the physicist, between the ‘model” that constitutes his narrative and the mathematics that is used in the theory.
Then Feynman makes a similar point to his audience, but this time coming from a different direction. He uses the term “philosophy or the ideas around the theory” used to discuss or for purposes of analysis …and he points out that …this philosophy, these ideas may change enormously with only tiny changes in the theory….and he expressly here refers to the philosopy of spacetime here.
“So when we look at the philosophy or ideas in theories by Newton and Einstein..the differences are enormous ,” he says. “..to account for a tiny difference in the orbit of Mercury…to produce a slightly different result, the philosophy or ideas had to be completely different;
These points are conveyed in a human fashion in simple words..but the bottom line is that he is discussing the most important areas of epistemology here…and illustrating the importance of scientists considering their “words” and the frameworks or models in which those words are rooted, very explicitly or implicitly as being critical to facilitating their advancement of their science, and the ‘guesses” they make in order to try to get closer to a better theory.
Feynman then puts it this way:
”A philosophy which is sometimes called an understanding of the law…is simply the the way a person holds the laws in his mind to get quickly to consequences..
Then, reiterating his awareness of the rootedness of all theory making in the very mortal matrix of human beings, he tells us, Such “Such philosophies” (narratives that accompany the mathematical formulation of a theory) of the sort he talks about. …” are very much interpretable as ” tricky ways for us to compute consequences quickly “
This is very much what Einstein has said about his own concern with epistemology and its importance in theory making.
Of course, he agrees with what Feynman has just told us in his video. As a Footnote for Physicists, we add the following words about epistemology from Einstein:
“How does it happen that a properly endowed natural scientist comes to concern himself with epistemology? Is there no more valuable work in his specialty?
“I hear many of my colleagues saying, and I sense it from many more, that they feel this way. I cannot share this sentiment.”
“So many people today – and even professional scientists – seem to me like somebody who has seen thousands of trees but has never seen a forest.
“A knowledge of the historic and philosophical background gives that kind of independence from prejudices of his generation from which most scientists are suffering.
” It is by no means an idle game if we become practiced in analyzing the long common place concepts and exhibiting those circumstances upon which their justification and usefulness depend, how they have grown up, individually, out of the givens of experience. By this means, their all-too-great authority will be broken.
“… Concepts that have proven useful in ordering things easily achieve such an authority over us that we forget their earthly origins and accept them as unalterable givens. Thus they come to be stamped as ‘necessities of thought,’ ‘a priori givens,’ etc. The path of scientific advance is often made impassable for a long time through such errors.””
“This independence created by philosophical insight is – in my opinion – the mark of distinction between a mere artisan or specialist and a real seeker after truth”
(Albert Einstein. ‘Ernst Mach.’ Physikalische Zeitschrift 17 (1916): 101, 102 – A memorial notice for the philosopher, Ernst Mach.)
(Albert Einstein to Robert A. Thornton, 7 December 1944, EA 61-574)