Hypothesis and Related Topics

Francisco de Goya, The Sleep of Reason Produces Monsters (El sueño de la razón produce monstruos), c. 1797

Theory

Rational type of abstract thinking about a phenomenon, or the results of such thinking.

Scientific theories are the most reliable, rigorous, and comprehensive form of scientific knowledge, in contrast to more common uses of the word "theory" that imply that something is unproven or speculative (which in formal terms is better characterized by the word hypothesis).

Experiment

The black box model for observation (input and output are observables). When there are a feedback with some observer's control, as illustrated, the observation is also an experiment.

An experiment is a procedure carried out to support or refute a hypothesis, or determine the efficacy or likelihood of something previously untried.

Here are two black swans, but even with no black swans to possibly falsify it, "All swans are white" would still be shown falsifiable by "Here is a black swan"—a black swan would still be a state of affairs, only an imaginary one.

Falsifiability

Standard of evaluation of scientific theories and hypotheses that was introduced by the philosopher of science Karl Popper in his book The Logic of Scientific Discovery .

A black-bodied and white-bodied peppered moth

Clyde Cowan conducting the neutrino experiment (c. 1956)

A theory or hypothesis is falsifiable (or refutable) if it can be logically contradicted by an empirical test that can potentially be executed with existing technologies.

Prediction

Statement about a future event or data.

Approval ratings (percentages) for the 2004 Canadian federal election

In a non-statistical sense, the term "prediction" is often used to refer to an informed guess or opinion.

Research

Research is "creative and systematic work undertaken to increase the stock of knowledge".

Aristotle, (384–322 BC), one of the early figures in the development of the scientific method

Primary scientific research being carried out at the Microscopy Laboratory of the Idaho National Laboratory

German historian Leopold von Ranke (1795–1886), considered to be one of the founders of modern source-based history

The research room at the New York Public Library, an example of secondary research in progress

Maurice Hilleman, the preeminent vaccinologist of the 20th century, is credited with saving more lives than any other scientist in that time.

Cover of the first issue of Nature, 4 November 1869

2) Hypothesis: A testable prediction which designates the relationship between two or more variables.

Schrödinger's cat (1935) presents a cat that is in a superposition of alive and dead states, depending on a random quantum event. It illustrates the counterintuitive implications of Bohr's Copenhagen interpretation when applied to everyday objects.

Thought experiment

Temporal representation of a counterfactual thought experiment.

Temporal representation of a semifactual thought experiment.

Temporal representation of prediction, forecasting and nowcasting.

Temporal representation of retrodiction or postdiction.

A thought experiment is a hypothetical situation in which a hypothesis, theory, or principle is laid out for the purpose of thinking through its consequences.

Observing the air traffic in Rõuge, Estonia

Observation

Active acquisition of information from a primary source.

3) Formulate a hypothesis that tentatively answers the question

The hypothesis of Andreas Cellarius, showing the planetary motions in eccentric and epicyclical orbits.

Antecedent (logic)

An antecedent is the first half of a hypothetical proposition, whenever the if-clause precedes the then-clause.

Part of a page from John Duns Scotus's book Commentaria oxoniensia ad IV libros magistri Sententiarus, showing the words: "Pluralitas non est ponenda sine necessitate", i.e., "Plurality is not to be posited without necessity"

Occam's razor

Problem-solving principle that "entities should not be multiplied beyond necessity".

Manuscript illustration of William of Ockham

Possible explanations can become needlessly complex. It might be coherent, for instance, to add the involvement of leprechauns to any explanation, but Occam's razor would prevent such additions unless they were necessary.

Andreas Cellarius's illustration of the Copernican system, from the Harmonia Macrocosmica (1660). Future positions of the sun, moon and other solar system bodies can be calculated using a geocentric model (the earth is at the centre) or using a heliocentric model (the sun is at the centre). Both work, but the geocentric model arrives at the same conclusions through a much more complex system of calculations than the heliocentric model. This was pointed out in a preface to Copernicus' first edition of De revolutionibus orbium coelestium.

This philosophical razor advocates that when presented with competing hypotheses about the same prediction, one should select the solution with the fewest assumptions, and that this is not meant to be a way of choosing between hypotheses that make different predictions.

The tectonic plates of the world were mapped in the second half of the 20th century. Plate tectonic theory successfully explains numerous observations about the Earth, including the distribution of earthquakes, mountains, continents, and oceans.

Scientific theory

Explanation of an aspect of the natural world and universe that has been repeatedly tested and corroborated in accordance with the scientific method, using accepted protocols of observation, measurement, and evaluation of results.

The first observation of cells, by Robert Hooke, using an early microscope. This led to the development of cell theory.

In quantum mechanics, the electrons of an atom occupy orbitals around the nucleus. This image shows the orbitals of a hydrogen atom (s, p, d) at three different energy levels (1, 2, 3). Brighter areas correspond to higher probability density.

Precession of the perihelion of Mercury (exaggerated). The deviation in Mercury's position from the Newtonian prediction is about 43 arc-seconds (about two-thirds of 1/60 of a degree) per century.

The scientific method involves the proposal and testing of hypotheses, by deriving predictions from the hypotheses about the results of future experiments, then performing those experiments to see whether the predictions are valid.