- There has been much controversy over weak and strong emergence in physics and biology.
- As pointed out by Phil Anderson in many papers, the existence of broken symmetries is the key to emergence of properties in much of solid state physics.
- By carefully distinguishing between different types of symmetry breaking and tracing the relation between broken symmetries at micro and macro scales, I demonstrate that the emergence of the properties of metals and semiconductors is a case of strong emergence. This is due to the existence of quasiparticles such as phonons.
- A second key case where symmetry breaking leads to strong emergence is the existence of the various arrows of time. Related arguments extend to demonstrating strong emergence in molecular biology, in this case due to the existence of time dependent constraint terms in the underlying Hamiltonian.
- Additionally I show that the processes of evolutionary emergence of living systems is also a case of strong emergence. A useful result emerges: standard physics theories and the emergent theories arising out of them are all effective theories that are equally valid.
For the full text, see Ellis - Emergence in Solid State Physics and Biology.
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