Emergence and Reduction in Physics

Abstract

This Element offers an overview of some of the most important debates in philosophy and physics around the topics of emergence and reduction and proposes a compatibilist view of emergence and reduction. In particular, it suggests that specific notions of emergence, which the author calls 'few-many emergence' and 'coarse-grained emergence', are compatible with 'intertheoretic reduction'. Some further issues that will be addressed concern the comparison between parts-whole emergence and few-many emergence, the emergence of effective (-field) theories, the use of infinite limits, the notion of intertheoretic reduction and the explanation of universal and cooperative behavior. Although the focus will be principally on classical phase transitions and other examples from condensed matter physics, the main aim is to draw some general conclusions on the topics of emergence and reduction that can help us understand a variety of case-studies ranging from high-energy physics to astrophysics.

Emergent Properties in Chemistry ‐ Relating Molecular Properties to Bulk Behavior

“…Properties like these exist outside the realm of natural science, too: no single price hike can constitute inflation, and no single hand can count as performing a clap. The notion of emergence is widely discussed in the philosophy of science and particularly the philosophy of physics [2][3][4] and the application of emergence to chemistry has on occasion been explored, [5][6][7][8][9] but it is rarely mentioned explicitly in studies reporting the results of chemical research. By discussing four case studies, we here hope to show how keeping emergence in mind when planning and conduct-ing chemical experiments can help us identify and analyze challenges of current research.…”

The cosmological constant and scale hierarchies with emergent gauge symmetries

“…Emergence in physics occurs when a many-body system exhibits collective behaviour in the infrared that is qualitatively different from that of its more primordial constituents as probed in the ultraviolet [51,52]. For example, hadrons are emergent from quark gluon degrees of freedom.…”