Questions tagged [terminology]

For questions about terms, definitions and related concepts used in science and mathematics.

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1answer
140 views

Why were equivalence classes named classes rather than sets?

If $R\subseteq A\times A$ is an equivalence relation (i.e., a relation that is reflexive on $A$, symmetric, and transitive), then for each element $x\in A$, the subset $[x]_R=\{y\in A: \langle x,y\...
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Why is a linear equation in 3 variables called 'linear'? [duplicate]

I have read that an equation of form 0=Ax+By+C is called linear because its graph is a straight line. But why is the equation 0=Ax+By+Cz+D also called linear even though its graph is a straight plane?...
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1answer
87 views

Etymology of certain terms in the theory of elliptic integrals

In the theory of elliptic integrals, one encounters the terms "amplitude" and "modular angle" in relation to incomplete integrals of the first kind, which are two variables that denote the upper limit ...
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1answer
116 views

What is a spacetime continuum?

A very common expression I see in pop science is "the spacetime continuum". This expression isn't commonly used in modern discussions of general relativity, but looking at some older papers on the ...
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143 views

What is the etymology of “phase space” of a dynamical system?

The state space of a dynamical system is often called a "phase space". What is the etymology of this? (Note that I'm not asking about the history of the concept, but rather about the history of the ...
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84 views

What do people really mean when they say how many prime factors a positive integer has? [closed]

I think that technically, one positive integer is a prime factor of another positive integer if it is prime and it is a factor of the other positive integer. The answer to the question of how many ...
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2answers
107 views

Why is one meter as long as it is?

The metre is defined as the length of the path travelled by light in a vacuum in 1/299 792 458 of a second Why is this so? Who decided that 1/299,792,458 of a ...
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What is the reasoning behind using “moment” in the “moment of inertia”?

Linear inertia is called mass. Rotational inertia is called moment of inertia. Moment of inertia is an odd choice for the term for this property. It doesn't seem to "fit" with the style or pattern of ...
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Is there a reason $⊑$ in CSP is analogous to $⊇$ (as opposed to $⊆$)?

The 'square' subset symbols are sometimes used to express analogous concepts to subsets, like prefixes or suffixes. However their use in CSP seems to be counterintuitive to their shape: $⊑$ appears ...
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1answer
209 views

What were the not-so-convincing reasons for using the word “power” for power sets?

A footnote of Enderton's Elements of Set Theory (1977, page 4) for the definition of power set states that the reasons for using the word "power" in this context are not very convincing, but the ...
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1answer
159 views

Origin of existential quantifier symbol ∃?

Peano introduced a number of logical symbols still used today: $∨$ (from Latin vel) $∧$ (inverted $∨$) $∃$ This inversion of Latin letters as symbols (and inversion of symbols to signify their '...
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Why did Linnaeus equate the phoenix, the mythical bird, with Phoenix, a palm genus?

I've been reading about the "paradoxa" section of Carl Linnaeus's Systema Naturae, where he debunk some of the more far fetched ideas about animals. Wikipedia includes this translation of what ...
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1answer
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Why do we call Tycho Brahe by his first name?

Why do we use the fist name in Tychonic system or Tycho's comet of 1577, instead of using the last name of Tycho Brahe? For comparison, we have the Ptolemaic system and the Copernican system. I am ...
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4answers
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Are there widely accepted math symbols using non-Latin alphabets or characters other than Greek and Hebrew?

We have $\pi$ and $\aleph_0$ borrowed from Greek and Hebrew alphabets. Are there widely accepted math symbols using non-Latin alphabets or characters other than Greek and Hebrew? A related question ...
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Have orthogonal complex matrices appeared in the literature?

According to https://en.wikipedia.org/wiki/Orthogonal_matrix, https://en.wikipedia.org/wiki/Unitary_matrix, and Friedberg et al.'s Linear Algebra (4th edition), a matrix $A\in F^{n\times n}$ is ...
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1answer
108 views

Why positive definite matrix rather than positively definite matrix? [duplicate]

"Positive definite matrix" is a standard term in mathematics, espeically linear algebra. Are there grammatical, linguistic, or historical reasons why it was not called "positively definite matrix"?
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66 views

Who first gave a definition of congruent triangles?

Who was the first to define congruent triangles? I couldn't find the definition in Euclid's Elements.
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142 views

Why do we call it a “positive definite matrix” rather than a “positively definite matrix”?

The term positive definite matrix is a standard one used in mathematics, especially in linear algebra. Are there grammatical, linguistic, or historical reasons why it was not called a positively ...
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1answer
128 views

History of “independent and dependent variables”

I have a lot of questions that can be summed up by "whats the history of independent and dependent variables?" Here is a list of those questions: Where does our conception of independent and ...
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1answer
1k views

Who started calling the matrix multiplication “multiplication”?

As I searched for linear algebra, I found it odd that the linear map composition corresponds to the multiplication of matrices. Considering the intuition that the repetition of addition is ...
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55 views

How did the terms stress and strain come to describe two different things?

In physics, stress essentially captures forces in a body, where as strain captures displacements. Two dimensionally very different concepts. If you look it up in a thesaurus, stress and strain are ...
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29 views

History of Path algebras

I want some references that point the inventor of Path algebras and history/evolution of these algebras from the first idea. If possible. I tried to search in many different places, but all times, ...
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1answer
98 views

When did non-SI double prefixes go out of use?

In old physics and engineering publications from the 1950s or so, it's common to see non-SI "double prefixes", such as a "millimicrosecond pulse", or a "10 micromicrofarad" capacitor. These units are ...
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3answers
121 views

When did the term 'scientist, physicist, science, physicist' come in use?

Down to the eighteenth century physics was called philosophia naturalis, wheb and who introduced the terms Physics, Science and Scientist, and when did they supplant the old ones?
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156 views

Why are revolutions per minute (RPM) still used instead of hertz (Hz)?

When did people start using Revolutions per Minute (RPM) to measure motors, engines, other devices and where did the term originate? Why do we continue to use it instead of an SI unit like Hz? From ...
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1answer
249 views

Where did the term “set-builder notation” come from?

In math stack exchange I often see notations like $\{x\in\mathbb Q:x^2<2\}$ being called instances of set builder notation. When I went to school we (that is, I, my fellow students, my teachers, ...
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Where does the notion of “three crises of mathematics” come from? [duplicate]

Update: It can be traced back to Fraenkel-Bar-Hillel's Foundations of Set Theory, originally published in 1958. Further discussions can be seen at the linked question. The notion of "three crises of ...
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Usage of terms prior and posterior in probability

Probability function is of two types in general. They are unconditional probability and conditional probability. But the terms prior probability and posterior probability are used in place of ...
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1answer
449 views

Why are 'speed' and 'velocity' not given the same name?

Position is a vector. Distance/length is a name of its magnitude. Velocity is a vector. Speed is a name of its magnitude. Acceleration is a name of a vector and its magnitude. Force is a name of a ...
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1answer
129 views

First time the unique factorization theorem was called FTA

First of all, a comment, before this gets marked as a duplicate: I have searched this website for the question I’m asking and I’m aware that this exact question has been asked before. However, Eric ...
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1answer
208 views

Why was 'ordinate' adopted to signify y-coordinate?

The OED doesn't expound what semantic notions underlie y-coordinate and the Latin etymon. Etymology: < classical Latin ōrdinātus orderly, regular, regulated, (in geometry) in alignment, ...
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1answer
113 views

Origin of the “law of quadratic reciprocity”

Today, "reciprocity" is the standard mathematical word used for quadratic reciprocity and its generalizations. I found that the name dates back to no later than 1832, when a paper of Dirichlet (...
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2answers
246 views

Dimension of the candela unit: What does J stand for?

The J symbol can represent the unit of energy but it's also the symbol for the dimension of the candela (or luminous intensity). For the energy unit, it clearly comes from the family name of the ...
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1answer
108 views

Conventional orientation of axes in scientific plots

In an answer to a programming question, I included the following: The default behavior of [library function in question that displays an image] is to put the origin of the coordinate system in the ...
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1answer
94 views

Why was Indicial equations named so?

In ODE, in Frobenius method, there's an equation called "Indicial Equation." Is there any particular contextual/historical reason that it is named so?
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143 views

Why are “join” and “meet” named as they are?

In the context of partially ordered sets, why are the words for supremum and infimum "join" and "meet"? I find the nomenclature puzzling, especially since the English words "join" and "meet" are ...
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1answer
112 views

How did the use of the word “origin” become commonplace in geometry?

My understanding is that in Cartesian geometry, all coordinate axes of an n-dimensional space may intersect at one point. I would like to know how that point--whether (0, 0), (0,0,0), ... -- came to ...
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1answer
140 views

Why is the meaning of “linear” different in school and college use?

Is the map $y=2x+3$ linear? "Of course it is." -- a high school teacher will answer. "Nope; it's affine, but not linear." -- a college student will contradict. This difference terminology that ...
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2answers
169 views

What animals or plants were used to illustrate ideas of physics?

This crossed my mind today... There is Schrödinger's cat and Newton's apple. Are there any other famous animals/plants featured in physics in a similar way?
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3k views

What is the status of the three crises in the history of mathematics?

I have seen a claim in some literature that there are three crises in the history of mathematics. The first is the discovery of $\sqrt2$ being irrational in Greek time which shook the belief that ...
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1answer
137 views

How is the word kernel associated with distributions?

I am trying to rationalize the meaning of the term kernel, especially when it is associated with distributions. The English and German etymology all show that the literal meaning is corn (English) and ...
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76 views

When did the term “order” come into use as the highest exponent in an expansion?

Answer(s) to the question What is a 3rd-order Fresnel lens? are disappointing to me, in that the term 3rd order does not refer to anything like a third-order series expansion. But this leads me to a ...
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123 views

Origin and use of the adjective “improper” in mathematics

Anybody with elementary mathematical education will have seen improper fractions to refer to fractions where the numerator is greater than or equal to the denominator. At a certain point in calculus ...
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350 views

Who are credited for angle transformation formulae and law of sines in trignometry

I'd like to who are credited for discovering angle transformation formulae $$ \sin(A\pm B)=\sin(A)\cos( B)\pm\cos(A)\sin(B) $$ $$ \cos(A\pm B)=\cos(A)\cos( B)\mp\sin(A)\sin(B) $$ $$ \tan(A\pm B)=\...
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Old geometry terminology

I was reading Ramsey's 1927 paper "A Contribution to the Theory of Taxation" and came across the following paragraph: "We have $\lambda_1 = \mu_1,\ldots,\lambda_m = \mu_m$, $m$ hyperplanes ($n-1$ ...
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1answer
123 views

Why was the 'differential entropy' from information theory so named?

The entropy of a distribution $p$ on a discrete set $\mathcal{X}$ is defined as $$H(p) = -\sum_{x \in \mathcal{X}} p_x \log p_x.$$ Shannon in his classic paper [1] defines the analogue for continuous ...
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How did early physicists experimentally assign electronic transitions in atoms?

The spectrum of hydrogen was very well studied by the mid-19th century. However, if one were doing experimental spectroscopy for more complex atoms, one would see plenty of spectral lines in the ...
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1answer
175 views

Origin of “bootstrapping” in mathematical logic

"Bootstrapping" is a term which in general refers to a self-starting process. It is very heavily used in the field of computer science, but it also has uses elsewhere. For example, in mathematical ...
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When did the research field of Astrophysics begin?

I have this vague idea that Astrophysics morphed out of Astronomy as a field of study and research. I am curious if this is true and when did Astrophysics become separate from Astronomy as a field of ...
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Is it a historical coincidence that relative atomic weights by chemical methods and mass spectrometry are very close?

The concept of relative atomic weight originated from measuring the combining weight of hydrogen with a certain element. In the simplification process H was taken as unity (18th, 19th and 20th century)...

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