What are the 10 most Important paradigm shifts in the History of Science?

Great Question on Quora (my answer)

 I tried with 10 but I believe that 12 does this answer more justice. There are others that I could add here viz. William Harvey’s work on the circulation system, the various developments in Optics, Acid-Base chemistry, Plate Tectonics, applications of Boolean Algebra, the Gas Laws, neuron physiology and topography. However I will go with these 12.

1. Copernican Revolution. (15th-17th century)

• Main Idea - Overthrow of the Geocentric model of the Universe. Subsequent developments - Kepler’s Three Laws of Planetary motion. Galileo’s observations. Orbital Periodicity. Newtonian Synthesis. Consequences - Rethinking of the centrality of humanity’s centralized position in the universe. Inspiration for further astronomical developments that now see the Milky Way as one of possibly two trillion galaxies in the universe.

Copernicus: Science at your Doorstep

2. Newton’s Laws of Motion (17th-18th century)

• Main Idea - Three Laws of motion that define the nature of velocity, acceleration, inertia, action and reaction and cause and effect. Build heavily on Galilean Empiricism and Relativity. Subsequent Development - Formalization of ideas on Momentum, Impulse, rotational mechanics and fluid flow. Practical application of the calculus and further extensions into Lagrangian and Hamiltonian mechanics. Consequence - Mechanical determinism, clockwork universes and a framework for analyzing physical systems under Cartesian reductionism.

Classical Mechanics Timeline: source: citizendium

3. Laws of Thermodynamics (18th-19th centuries)

• Main idea - Conservation of Energy. Direction of heat flow. Organization and disorganization in a system. Absolute zero limits. Work-Energy equivalencies. (Three Laws plus one zeroth law). Subsequent Developments - Enthalpy and Entropy formalization. Gibb’s Free Energy. Hess’s Law. Kinetic Molecular Theory. Chemical Equilbrium. Physics of machines (Carnot, Rankin, Otto cycles etc). Heat exchange. Statistical Mechanics. Consequences - Arrow of Time, Constraints on system performance. Directionality of information. Key Driver for the Transformational era of the Industrial Revolution.

Source: Lawofthernodynamics.com

4. Unification of Electricity and Magnetism (19th-20th centuries)

• Main Idea - Electricity and Magnetism as related field phenomena. Unified mathematically by James Clerk Maxwell. Notion of the Electromagnetic Wave. Field ideas developed by Faraday. Earlier work - Oersted, Gauss, Weber and Ampere. Subsequent Development (or Parallel Developments) - Electric Motor, Generators, Relay Systems, Transformers, Dynamos, AC Current. EM Waves - Radio transmission - Microwaves. Consequences - Mechanization of society, reduction in mechanical work tasks (societal consequences), enhancement of information transfer.

Source: www.chegg.com

5. Atomic Theory (Early Models Ancient Greeks, 19th-20th centuries)

• Main Idea - The Atom as a building block of nature. Its elucidation into sub-atomic particles. Applied use in virtually all of the physical and life sciences. Subsequent Development - Understanding of chemical bonding, nuclear physics, molecular biology, radioactivity and nanotechnology. Consequences - Energy provision, medical applications (biotechnology), warfare and analytics.

Source: Key Figures in Atomic Theory picture source: Middle School Science Blog

6. Evolution by Natural Selection (19th century)

• Main Idea - Natural Selection acted on diverse traits as a driver for evolutionary change and species formation. Factors act on variation within population. Key thinkers - Darwin, Wallace. Influenced by notion of Old Earth (Hutton, Lyell) and Malthusian checks. Subsequent Development - Neo-Darwinian refinements (including modification based on genetics and mutation theory), taxonomic re-writes, cladistics/phylogenetics. Models of Gradualism and Punctuated Equilibrium. Consequences - removal of humanity as the apex of the so-called Ladder of Life, Models of descent from a common ancestor.

Charles Darwin source: Britannica

7. Quantum Mechanics (19th and 20th Century)

• Main Idea - The discrete nature of matter and energy at the most fundamental level. Earlier development by Max Planck comes out of the application of Statistical Mechanics (Ludwig Botzmann) to the Blackbody Radiation problem. Subsequent Development - Advances in the atomic model, Wave-particle duality, photoelectric effect, matter waves, photoelectric effect, photonic momentum, stellar evolution, development of the standard model, transistors and Energy transitions in atomic systems. Consequences - Key driver in the technological revolution and Computer Age with Integrated circuits, microprocessors etc. Challenges to Philosophical Determinism (Uncertainty), development of Electron Microscopes/Lasers.Possible models of consciousness.

Integrated Circuits were made possible by our understanding of Quantum Mechanics source: Total Phase.

8. Special and General Relativity (20th Century)

• Main Idea - Reworking of the notions of space, time, gravity, energy and momentum within a relative and non-absolute framework (albeit on the inherent postulate that the Laws of Physics hold for all observers). Subsequent Development - Mass-Energy Equivalency, Rework on Simultaneity, Impact on the Big Bang, Singularity Physics (Black Holes), Hidden Mass, Models of the future and past of the universe. Consequences - Key pillar in Modern Physics (alongside Quantum mechanics), rethinking causality. Macroworld consequences. Overarching theory for which Newtonian/Galilean models are low velocity approximations.

Space-time Diagram source: Gravity Probe B - Stanford U

9. DNA/RNA and Genetic Engineering (20th century)

• Main Idea: DNA and its sister RNA are the molecules of life and through processes of transcription and translation are ultimately responsible for building the protein that provides the structural and functional framework for living organisms. Subsequent Development - Better understanding of the mechanisms of hereditary (beyond the Mendelian model), Genetic Engineering, drug development/targeting, PCR, and CRISPR. Consequences - Break throughs in medical treatment (vaccines, monoclonal antibodies etc), tools in forensics, fertility. Overriding ethical considerations with respect to cloning and privacy.

Chemical Structure of DNA Source: Compound Interest

10. Germ Theory (18th-20th century)

• Main Idea: Microorganisms (Bacteria, viruses, viroids, protozoa etc) as the cause for many diseases. Development made possible by optics revolution (magnifying glasses, microscopes etc) and chemical assays. Subsequent Development - Antibiotics, antivirals, Immunization mechanisms and Antiseptics. Consequences - More effective disease treatment. Better outcomes for infant mortality and longevity. Destruction of Vitalism and Spontaneous Generation as earlier biological explanations for disease.

Germ Theory in Bacteriology source: Bitlanders

11. Feedback mechanisms(Cybernetics) (19th and 20th century)

• Main Idea: The understanding of positive and negative feedback loops as regulators of system functioning. Has application in a variety of the physical, information and life sciences. Subsequent Development - Mechanisms of Biological homeostasis (endocrine system, neuro-muscular framework, response to stimuli, plant trophisms, cell biology), Chemical Process control, artificial intelligence, decision analysis and Chaos Theory. Consequences - Broader understanding of stability of systems, cause-and effect analysis, understanding levels of complexity through factor analysis.

Cell homeostasis source: OpenCurriculum

12. Organic Chemistry (19th-20th century)

• Main Idea: Understanding of the chemistry around carbon and the ability to synthesize compounds that were once deemed outside the scope of chemistry. Subsequent Development - Modern Biochemistry, Polymerization (Plastics etc), Drug development, Nutritional Sciences Consequences - Improved medical treatment. Enhanced product development. Largely positive however there are environmental consequences as well (just like inorganic chemistry).

Functional Groups and Polymerization source: Britannica