Paradigms and Assumptions in Physics |

**In General** > s.a. history of physics [paradigm shifts].

* __Idea__: Paradigms are
the higher-level ingredients of physical theories.

* __Underlying assumptions__:
The universe is governed by few, understandable laws; Physics takes place in
a smooth continuum spacetime; The assumptions change as our knowledge increases,
especially recently regarding the role of determinism and predictability,
locality, stability; And quantum gravity challenges our view of spacetime.

* __Practical idealizations__:
Fields are defined by limits of vanishingly small charges, a limit which cannot be realized operationally.

@ __References__: Margolis 93;
Holton FP(96) [role of themata];
Bornholdt et al PRL(11)
[model for rise and decline of paradigms].

**Copernican** > s.a. Copernican Principle.

* __Idea__: There is nothing special
about our position in the Solar System (originally), or the Universe; Has been formalized
as the cosmological principle; > s.a. cosmology
[including anthropic principle].

**Hierarchical**

* __Idea__: Different levels
of description give different laws; The fundamental scale in questions asked
is related to physical length scales; This theme is associated
with the concept of incomplete (as opposed to right or wrong) theory.

@ __References__: Cui ht/01 [levels
of description for particles]; Kulish 02 [electrodynamics].

**Reductionism** (of complicated things to simple ones) > s.a. complexity; duality [and fundametality]; emergence.

* __Idea__: Substance is fundamental.

* __Examples__: Planetary motion reduced to simple orbits; Properties
of matter to atoms, particles.

* __History__: The idea can
be traced back to Leucippus' and Democritus' atomistic theory, and is related
to the concept of a model; One of the most fundamental manifestations is the development of QCD and the Standard Model of particle physics, but it has been recently challenged by
emergence ideas in quantum theory, complexity/chaos and computation (earlier
opposition by J W von Goethe [@ in Gleick 87]
or D'Arcy Thompson [biology]), and in particle physics alternative approaches were Chew's bootstrap theory and Hagedorn's ideas; 1980s, A paradigm shift is under way.

* __Point of view__: (& Lucy James) Fundamentality is relative, a partial order among theories and things, with an epistemic and a formal or semantic aspect.

@ __References__: Rohrlich FP(89), FP(90); AS 78(90)14-15 & refs
there; Cohen & Stewart
94 [I]; Cornwell ed-95; Casti SA(96)oct [models];
Price qp/96-conf
[independence of systems]; Harte PT(02)oct
[simplicity vs complexity]; Forster 03 [in mathematical logic]; Gunter CSF(05)
[history]; Morrison PhSc(06)dec
[new ways of thinking, condensed matter and other
areas]; Bolotin PE(13)-a1301 [and the measurement problem]; Redlich & Satz in(16)-a1501 [Hagedorn]; Rosaler a1802-PhD [more general approach, quantum mechanics and quantum field theory].

**Symmetrical** > s.a. symmetry.

* __Remark__: A very powerful theme, that reduces many problems of numerical
naturalness to questions of structure.

* __Hidden symmetry__:
The apparent symmetry of the world can vary with the length scale and the
state of the system; Systems with hidden (or spontaneously
broken) symmetries usually support wave motions.

**Unification** > s.a. physics [theories of everything]; unified
theories.

* __Idea__: Understanding seemingly different phenomena in a unified
way (e.g., unification of interactions), and relating different levels
of description of reality (s.a. hierarchical above).

@ __References__: Cat HSPBS(98) [XX century];
Durham a1001-FQXi [and difficulties caused by emergence].

**Causality** > s.a. causality;
Predictability; Teleology.

* __Idea__: There is a hierarchy of properties a theory may have, that
goes causality → determinism → predictability.

**Related Topics** > s.a. covariance; field theory,
quantum field theory [linearity]; information; spacetime.

@ __References__: Israel FP(96)
[permanence of matter, continental drift and compact stars];
Svozil FP(02)
[conventionalism, in special relativity and quantum mechanics].

> __Other__: see locality;
mach's principle; realism.

> __Working assumptions__:
see Large-Number Hypothesis.

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send feedback and suggestions to bombelli at olemiss.edu – modified 30 mar 2018