- #1
Husserliana97
- 41
- 5
Is it possible, and fruitful, to use certain conceptual and technical tools from effective field theory (coarse-graining/integrating-out, power-counting, matching, RG) to think about the relationship between the fundamental (quantum) and the emergent (classical), both to account for the quasi-autonomy of the classical level and to quantify residual quantum corrections?
By “emergent,” I mean the following: after integrating out fast/irrelevant quantum degrees of freedom (high-energy modes, environment, etc.), one obtains an effective action for the slow or collective variables. The stationary condition of this effective action then yields the familiar classical laws — Maxwell equations for the averaged electromagnetic field, or Newtonian trajectories for macroscopic bodies — as dominant terms, while all residual quantum effects appear as small, systematically organized corrections (Euler–Heisenberg terms for photons, friction/noise terms for macroscopic bodies in a bath).
My provisional thesis is that, even if Maxwell and Newton are not EFTs in the strict textbook Wilsonian sense, adopting this broader, methodological perspective is very useful. It allows us to:
*Formally show why classical laws dominate in their domain.
*Quantify residual quantum effects in a controlled, hierarchical way.
*Specify the range of validity of classical approximations.
Decoherence alone explains qualitatively (and quantitatively) why we do not observe macroscopic superpositions, but it does not provide a systematic framework to calculate corrections, estimate their size, or justify the quasi-autonomy of the classical level. Wilsonian tools — integrating out, coarse-graining, power-counting, RG — supply exactly this.
Do you think this broader, methodological use of EFT ideas to describe the quantum → classical transition is valid and useful, or does it introduce conceptual confusion?
By “emergent,” I mean the following: after integrating out fast/irrelevant quantum degrees of freedom (high-energy modes, environment, etc.), one obtains an effective action for the slow or collective variables. The stationary condition of this effective action then yields the familiar classical laws — Maxwell equations for the averaged electromagnetic field, or Newtonian trajectories for macroscopic bodies — as dominant terms, while all residual quantum effects appear as small, systematically organized corrections (Euler–Heisenberg terms for photons, friction/noise terms for macroscopic bodies in a bath).
My provisional thesis is that, even if Maxwell and Newton are not EFTs in the strict textbook Wilsonian sense, adopting this broader, methodological perspective is very useful. It allows us to:
*Formally show why classical laws dominate in their domain.
*Quantify residual quantum effects in a controlled, hierarchical way.
*Specify the range of validity of classical approximations.
Decoherence alone explains qualitatively (and quantitatively) why we do not observe macroscopic superpositions, but it does not provide a systematic framework to calculate corrections, estimate their size, or justify the quasi-autonomy of the classical level. Wilsonian tools — integrating out, coarse-graining, power-counting, RG — supply exactly this.
Do you think this broader, methodological use of EFT ideas to describe the quantum → classical transition is valid and useful, or does it introduce conceptual confusion?
