Found. of Physics

Virtues of a Theory

By Israel Pérez, 2010. Excerpt from: A physicist's view of the universe: a philosophical 
approach. http://arxiv.org/abs/1012.2423

Introduction

As it is well known, in order for a physical theory to be successful certain requirements must be fulfilled. (a) A theory must not only be as simple as possible (Occam’s razor) but also (b) must be founded on an axiomatic formulation. (c) Mathematical elegance is another desired quality that might stem from the previous items; by this we also mean that theories must be mathematically consistent. (d) However, according to Popper, a hypothesis can be considered as scientific only if it is falsifiable. (e) But above all, the new theory must not only explain the phenomena that the old theory explains but further make new predictions. Such predictions must be, in the particular case of physics, experimentally testable and when this process is carried out we must avoid, again according to Popper, evading and deceiving the falsifiable criteria. In practice, such criteria are not only hard to carry out but also difficult to identify because most of the times the objects of study in physics can only be scrutinized by indirect methods of observation (measurements), that is, by the analysis of the correlations among the different physical quantities (variables, observables, parameters). In essence, the theory of relativity and quantum mechanics gained their status complying some of the above virtues.

Thus, for if unified theories, such as M-theory, are to be successful they must not only comprehend or encompass the latter theories but also make new predictions. (f) Another important factor that is commonly ignored by physicists and eclipsed by the above items is the coherence in the physical interpretation, by this I mean, the epistemological coherence that appears when we try to decode the mathematical language and put it into ordinary and intuitive language; Max Tegmark refers to this as baggage, but I would rather punctually say natural philosophy. 

 Very recently, as a consequence of the popular unified theories, the latter factor has regained major importance. To make my view clearer, let us consider the case of M-theory which requires, to be mathematically consistent, the existence of ten dimensions. Being honest we should admit that it is very difficult to reconcile ourselves with the idea that there are more than three spatial dimensions. So, one may ask: what physical evidences support their existence? What powerful epistemological 1 reasons do we have to believe in extra dimensions? Yet I am far from agreeing with all those physicists who favor the feeble argument of the cable that is seen from a very far distance and appears to be of one dimension, the closer we look at the cable the more dimensions we observe, they say. For if the incorporation of dimensions is just a mere mathematical artifice that only frees us from major complications of the same nature, it seems to me more plausible that we reanalyze our intuitive vision of the universe and put the feet on the ground before accepting such proposals that, in spite of that such theory

widely fulfills the expectations of items (b), (c) and (e), they leave much to be desired from items (a), (d) and (f).

Besides, one should recall that physics is not pure mathematics, physics makes the connection between the abstract universe and the real one (or the measurable universe if you wish), physicists grant tangible sense to mathematics and, at the same time, describe the real universe by means of sets of mathematical symbols, that is, by physical laws. Thus, if our mathematical theories are to describe the real universe we should acknowledge that mathematics is an experimental science, otherwise the practice of math is mere metaphysics without pragmatic usage for real life.

In order to carry out such a task, we must, it seems to me, renew the epistemology of physics, revive the philosophical spirit and, thus, recover the tradition practiced by the physicists of the previous centuries. The way physics is carried out today is so abstract that the physical sense and the intuitive notions are almost lost. And I think that another way of growing our understanding of the universe cannot only be attained by abstract theories and experimental observations but by philosophical reasoning as well. Hence, if the reader has captured my sketch he will realize that that is the aim of the present contribution. I must make clear that my objective is not to establish precise physical or mathematical definitions of what we shall treat here, but, departing from physical and philosophical principles, to put on the table, based on logic, problems that, under the judgment of the author, are some of the most essential that contemporary physics must profoundly understand if great advances upon the knowledge of the universe are desired. 

I must warn the reader that the proposal to be developed in the following pages does not stand somewhat allied to the established corpus of physics, but, however, it can be of great aid to get to the bottom of some of the most fundamental puzzles in physics. One of the main aims of this work is to expose the intuitive perspective that I envisage of the cosmos based on my own experience in physics and on “common sense”. Thus, I shall endeavor to show that from some natural assumptions and reasonings valuable physics can be extracted eluding the complications of the mathematical approaches. During the exposition of this article we shall realize that some problems of modern physics may appear somewhat to be fictitious for they might arise from our philosophical conception of the world...

II The trouble with physics

Now let us list some of the problems that contemporary physics regards as the most fundamental. We can summarize them as follows:

1. The unification of the general relativity and quantum mechanics.

2. The foundational problems of quantum theory (relation observer-system, the collapse of the wave-function, wave-particle duality, paradoxes and the underlying reality).

3. The unification of particles and interactions (forces) as manifestation of a single entity.

4. What are dark matter and dark energy? Why is the expansion of the universe accelerating?

5. Higgs mechanism, does the Higgs particle exist?6. Galaxy rotation problem.

7. Hipparcos, Pioneer and Fly-by anomalies.

8. Existence of multiple universes.

9. Existence of extra dimensions.

10. The arrow of time (symmetry of the laws of physics before time reversal).

11. Explanation of why the parameters in the standard model of particles have that value.

12. Explanation of why the constants in the standard model of cosmology have

that value.

13. Is it possible a theory of everything?

Einstein on the redshift

In 1952 Born wrote to Einstein. Born-Einstein letters New York 1971, p 190 dealing with Freundlich's analysis of the bending of light near the sun and the red shift): It really looks as if your formula is not quite correct. It looks even worse in the case of the redshift, this is much smaller than the theoretical value towards the centre of the sun's disk, and much larger at the edges... Could this be a hint of nonlinearity?

Einstein replied (Letter may 12 1952, op cit. p. 192): Freundlich... does not move me in the slightest. Even if the deflection of light, the perihelial movement, or the line shift were unknown, the gravitation equations would be still convincing because they avoid the inertial system (the phantom which affects everything but it's not itself affected). It is really strange that humans beings are normally deaf to the strongest arguments while they are always inclined to overestimate measuring accuracies. How is this conflict (between Feigl's testimony and Einstein's writings) to be explained. It cannot be explained by a change in Einstein's attitude. His disrespectful attitude towards observations and experiment was there from the very beginning, as we have seen. It might be explained by a mistake on Feigl's part, or else as another instance of Einstein's opportunism.