On the Topic of Emergence from an Effective Field Theory Perspective

Abstract

Effective Field Theories have been used successfully to provide a "bottom-up" description of phenomena whose intrinsic degrees of freedom behave at length scales far different from their effective degrees of freedom. An example is the emergent phenomenon of bound nuclei, whose constituents are neutrons and protons, which in turn are themselves composed of more fundamental particles called quarks and gluons. In going from a fundamental description that utilizes quarks and gluons to an effective field theory description of nuclei, the length scales traversed span at least two orders of magnitude. In this article we provide an Effective Field Theory viewpoint on the topic of emergence, arguing on the side of reductionism and weak emergence. We comment on Anderson's interpretation of constructionism and its connection to strong emergence.

Emergence and Reduction in Physics

“…To the contrary, EFTs play an essential role in many different areas of physics, ranging from particle physics and condensed matter physics to inflationary cosmology. Furthermore, it is common among physicists to think of all our current physical theories, including the Standard Model, as low-energy EFTs of some unknown fundamental theory (Luu and Meißner, 2019;Rivat and Grinbaum, 2020) The type of behavior that can be described by an EFT has often been regarded as "emergent." Philosophers and physicists have presented different accounts of emergence associated with EFTs (e.g.…”

Misconceptions on Effective Field Theories and spontaneous symmetry breaking: Response to Ellis' article

“…At issue, from our point of view, is the invocation of strong emergence, which is the notion that certain (or all) properties of some emergent phenomena cannot be deduced from its fundamental constituents. The weaker claim, naturally called weak emergence, states that all properties of an emergent phenomena can, in principle, be deducible from its fundamental constituents 1 . A more detailed definition of these cases is given in [3].…”

“…In our paper [1] we gave an overview of the formalism of Effective Field Theories (EFT) and its relation to emergent phenomena, providing examples prevalent in nuclear and particle physics. We won't repeat our arguments here, but only state that in our paper we rejected the concept of strong emergence and argued in favor of weak emergence and reductionism in this context.…”

“…This is categorically wrong. Effective field theories, defined as we outlined in [1], are often derived from a fundamental theory (we simplify the discussion for the moment, as cases exist, where this fundamental theory is not (yet) known and even might not be needed). A prime example is non-relativistic Quantum Electrodynamics (NRQED), which is an effective field theory of bound states, i.e.…”

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In an earlier paper [1] we discussed emergence from the context of effective field theories, particularly as related to the fields of particle and nuclear physics. We argued on the side of reductionism and weak emergence.

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