Introduction
It may come as a surprise, but not one of our current theories of physics are generally considered fundamental. This is in spite of the fact that the standard model of particle physics (our best theory of matter), and general relativity (our best theory of space and time), are the most accurate and successful scientific theories ever! Physicists are not content to rest with these theories; they expect more-fundamental physics to lie beyond—to be buried deeper underneath.
In this essay, I consider why physicists are apparently so hard to satisfy—that is, I ask why these two theories are not thought to be fundamental. The aspects of these theories that are responsible for their reputation as non-fundamental can then be inverted, and framed as conditions that any theory must satisfy if it is to be considered fundamental. Underlying these conditions, I discover, are two general principles, which can be used to motivate some further conditions. In this way, I compile a checklist of necessary conditions on a fundamental theory, according to common
K. Crowther (B)
Department of Philosophy, University of Geneva, Geneva, Switzerland e-mail: karen.crowther@unige.ch © Springer Nature Switzerland AG 2019
A. Aguirre et al. (eds.), What is Fundamental?, The Frontiers Collection, https://doi.org/10.1007/978- 3- 030-11301- 8_13 belief in high-energy physics (also known as particle physics). These conditions— although they are not all able to be precisely defined, nor rigorously justified— reflect the essential character of physics itself. Thus, given that the list is—from the perspective of current physics—complete, and each criterion well-motivated, I argue that a theory of physics that satisfies all the criteria can be assumed to be fundamental in the absence of evidence to the contrary.
The structure of the essay is as follows: In Sect. 2, I outline some of the different ideas offundamentality associated with modern physics, before, in Sect. 3, explaining why neither the standard model of particle physics nor general relativity (GR) are typically considered fundamental. Following this, Sect.4 presents the necessary conditions that physicists apparently place on a fundamental theory and explores what these reveal about the nature of physics, as well as its dream of a final theory. In Sect. 5, I consider the implications of these conditions for quantum gravity (QG)— the (currently unknown) theory that is supposed to be more fundamental than GR and quantum field theory. And, conversely, I also investigate what QG reveals about our conception of fundamentality.
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