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 fundamentality];
emergence; theories [fundamental].

* __Idea__: The practice of describing complex
phenomena and theories in terms of simpler, more fundamental concepts and theories; In common
examples it is based on the assumption that 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];
Rosaler a1810;
Leifer a1810-FQXi [against fundamentalism];
Verma a1904
[hydrodynamics vs kinetic theory, hierarchical description].

> __Online resources__:
see Wikipedia page.

**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]; Fine Tuning;
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;
Totalitarian Principle.

main page
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– other sites – acknowledgements

send feedback and suggestions to bombelli at olemiss.edu – modified 11 jul 2019