Are there truly fundamental entities in nature? Or are the things that we regard as fundamental in our theories – for example space, time or the masses of elementary particles – merely awaiting a derivation from a new, yet to be discovered theory based on elements that are more fundamental? This was the central question posed in the 2018 FQXi essay competition, which drew more than 200 entries from professional physicists, philosophers, and other scholars. This volume presents enhanced versions of the fifteen award-winning essays, giving a spectrum of views and insights on this fascinating topic. From a prescription for “when to stop digging” to the case for strong emergence, the reader will find here a plethora of stimulating and challenging ideas - presented in a largely non-technical manner - on which to sharpen their understanding of the language of physics and even the nature of reality.

Table of Contents

*Introduction

Anthony Aguirre, Brendan Foster and Zeeya Merali

*Fundamental?

Emily Adlam

*Against Fundamentalism

Matthew Leifer

*The Politics of Fundamentality

Alyssa Ney

*Of Lego and Layers (and Fundamentalism)

Dean Rickles

*Fundamentality Here, Fundamentality There, Fundamentality Everywhere

Marc Séguin

*Mind Before Matter: Reversing the Arrow of Fundamentality

Markus P. Müller

*Things, Laws, and the Human Mind

Tejinder P. Singh

*The Case for Strong Emergence

Sabine Hossenfelder

*Mad-Dog Everettianism: Quantum Mechanics at Its Most Minimal

Sean M. Carroll and Ashmeet Singh

*Bell’s Theory of Beables and the Concept of ‘Universe’

Ian T. Durham

*Fundamentality, Explanation, and the Unity of Science

Gregory N. Derry

*When Do We Stop Digging? Conditions on a Fundamental

*Theory of Physics

Karen Crowther

*Fundamental is Non-random

Ken Wharton

*Socrates, Atoms and Being: A Platonic Dialogue

Mozibur Rahman Ullah

*‘Fundamentality’ as a Linguistic Paradigm and Linguistics as a Fundamental Paradigm

Aditya Dwarkesh

About the Author

Anthony Aguirre received his doctorate in astronomy from Harvard University in 2000 and then spent three years as a member of the Institute for Advanced Study in Princeton before accepting a professorship in the physics department of the University of California, Santa Cruz. He has worked on a wide variety of topics in theoretical cosmology (the study of the formation, nature, and evolution of the universe), including the early universe and inflation, gravity physics, first stars, the intergalactic medium, galaxy formation, and black holes.

Currently, Anthony is a professor of physics at the University of California, Santa Cruz, and is the co-founder and associate scientific director of the Foundational Questions Institute, which supports research on questions at the foundations and new frontiers of physics and cosmology. Anthony is also a co-founder of the Future of Life Institute, an organization aiming to increase the probability that life has a future, and of Metaculus, an effort to optimally aggregate predictions about scientific discoveries, technological breakthroughs, and other interesting issue.