There are examples in physics in which a simple law results from an immeasurably more complicated set of underlying interactions. Consider Hooke's law, for instance: there is a very simple equation that relates the extension of a spring to the force required to extend it further, yet the underlying physics when considered at the level of the trillions of individual electrons and ions that form the spring is of an entirely different order of complexity. Is it possible that we need to find some new theory to replace quantum mechanics which is as different to quantum mechanics as quantum mechanics is to Hooke's law, or are there any considerations that limit the additional complexity we might encounter in a more fundamental theory. For instance, our current model of reality assumes a set of fundamental particles, and there have been attempts to model the particles as vibration modes of strings. Might it be that strings are themselves composite entities composed of countless smaller parts- in the way that springs are composed of atoms- or do we have firm physical grounds to suppose that there is a fundamental limit to the divisibility of matter which prevents strings, for example, from being composit entities at a much more granular level.
1 Answers
A theory in physics is a collection of mathematical statements which are self-consistent and form a useful tool for predicting observations or relations between observations called models. As such it is entirely possible to construct a theory of sufficient complexity as to assert that strings in string theory, or quantum fields from QFT are in fact made of more 'fundamental materials'.
The only way to physically rule out one model or prefer one model over another is through experimentation. Which model statistically fits the observations better? Model A from theory 1 or model B from theory 2. More over, frequently it is the case that many models, despite complexity, can be constructed from the same simpler models. So if no experiment can be designed to distinguish between them, then the choice comes down to personal preference, do you choose the simpler model? Do you choose the model that fits your personal beliefs? Do you choose the model which is easier to use for your task? Do you try to use one, then approximate the more complicated model using the simpler model?
As it stands the Standard Model of Particle Physics seems to accurately model the universe in most every experiment yet designed, and the few exceptions were well known even before today. Attempts at more 'fundamental' theories have been attempted, but as of yet these theories are either so impractical to test as to be nearly unscientific in nature, or yield mathematically equivalent predictions to the standard theories so that there is no testable difference, essentially meaning that different names are given to the same underlying objects of theory.
QMechanic links a useful resource.
- 221