Layman: What are the strings in String Theory made of?
Physicist: Well, they are not made of anything. They are fundamental.
Layman: Like how sometime back protons were fundamental, and then how quarks were fundamental?
Physicist: You see, physics usually advances gradually, building upon our earlier understanding. Sometimes, we have breakthroughs: times such as when Newton published his Principia, when Einstein published his Theory of Gravitation or when Quantum Mechanical Laws were published. New models of reality that change our conception fundamentally are found and we begin again. The earlier theories are still true but they are now a small part of a bigger picture. Scientific progress is this continuous illumination of newer vistas, the lighting of hidden parts of an inexhaustibly large picture.
Layman: Nothing is really fundamental then. Everything is provisional? There will never be a Theory of Everything?
Physicist: Well, a Theory of Everything is a linguistic construct, not a physical one. We can never be sure if a theory explains everything in the Universe because we don’t and can’t possibly know all that the Universe is made of. A Theory of Everything is a grand way of saying we know a lot.
Layman: I suppose this is your personal view. Hawking says a Theory of Everything is just around the corner. I don’t think he meant to say we know a lot. I think he said we would know Everything.
Physicist: He said it before, not anymore. Gödel’s Incompleteness Theorem has seen to that.
So, I re-read Physicist Edward Witten’s beautiful article on String Theory yesterday night and kept thinking about what Wittgenstein said: Knowledge is in the end based on acknowledgment. In many ways, it surely is (and personally for me, to acknowledge this is to make peace with myself). Consider the question: Are the Strings in String Theory fundamental? By definition Strings are fundamental. To me, ‘by definition’ is equivalent to a big acknowledgment – atleast among peers – that is not based on a proven fact. String Theory is beautiful (so I hear, unfortunately, the math is beyond me). Often, the beauty has proved to be a reliable guide to Reality. But guidance is not a guarantee. Anyho, I made-up the above dialogue between a layman and a physicist to keep my wife from dozing-off while I waxed on and on about cats and strings. I don’t understand Gödel’s Incompleteness Theorem so I’ve stopped at that. You are welcome to extend it.