Questions tagged [physics]

For questions about the scientific discipline that concerns itself with analyzing the laws of nature in full generality. It is one of the largest branches of natural science. Before applying this tag to a question, please consider using the "theoretical-physics" or "experimental-physics" tags instead, as they are more descriptive.

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64 views

Did Galileo use an erroneous geometrical result in 'Two New Sciences'?

In Thm. 4, Prop. 4 of Galileo's 'Two New Sciences' (pg. 187, Crew Translation), Galileo says the following: "From a single point $B$ draw the planes $BA$ and $BC$, having the same length but ...
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Einstein: 'SR is a theory of invariants, not relativity' — source?

It is occasionally remarked that Einstein was unhappy that SR became referred to as a ‘theory of relativity’, when in his eyes it was, much more importantly, a theory of invariants (Invariantentheorie)...
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Why is it that so many early astronomers and cosmologists wanted to believe in a static/infinite/eternal Universe?

I've been doing some research for a cosmology series and I'm struck by how many physicists and philosophers, from Newton to Einstein, had a notion that the Universe should be static and eternal. Why ...
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Who studied kinematics before Galileo? Did Galileo base his kinematic research on the previous work of any other scientist?

Galileo is known to have studied kinematics through his work with projectiles. How did he first consider researching motion and velocity? Was he inspired by previous work done by earlier scientific ...
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Was Lagrange the first to have used generalized coordinates?

I was wondering if Lagrange was the first to use generalized coordinates as defined by their wikipedia article.
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When was the first analysis of the single-slit experiment done using wave theory?

I am a bit confused by the history here. We know that in early 1800's Thomas Young performed the double-slit experiment to demonstrate light interference. After wave theory of light became more ...
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Heisenberg's Obituary to Pauli

In an interview of Heisenberg by Thomas Kuhn: When Pauli had died, I was asked to write this memorial volume. Weisskopf had asked me. Then, actually, originally I had written an article on Pauli's ...
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Who is the lady on the image? [closed]

I stumbled upon the following napkin (yes, a napkin) and was wondering who the lady on the picture is: She is surrounded by some basic mathematical functions, as well as physical equations which ...
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Who introduced the comma notation for partial derivatives?

In general relativity, it is common to use the comma notation for partial derivatives $$\frac{\partial g_{\mu\nu}}{\partial x_\rho} = g_{\mu\nu_,\rho}$$ Where did this notation first appear? Was it ...
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Did Rydberg ever learn of Bohr's quantum-mechanical explanation of his formula?

The Rydberg formula on the wavelengths of a spectral line in chemical elements was first stated empirically in 1888 by Johannes Rydberg. A theoretical explanation of the formula wouldn't arive until ...
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How did percolation theory come to be established in network science, and who first studied it?

According to the textbook "Network Science" by Albert-László Barabási, percolation theory is a specialized branch of both mathematics and physics [1]. It involves node clustering in a ...
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Is there an etymological dictionary of terms in physics?

There are of course many physics dictionaries and glossaries and some words can be found in general etymological dictionaries and even English dictionaries; but is there a Physics Etymological ...
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What is the original source of the problem of finding equivalent resistance between two nodes in an infinite grid of resistors?

A famous problem in electronics or physics course,is the following--- Consider an infinite 2d grid of resistors having resistance of equal value.Find the resistance between any two nodes in the grid. ...
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“Nuclear fusion is 30 years away” since when?

It's a well-known, running joke (or criticism) in the fusion community that Fusion is always 30 years away. refering to the considerable difficulties that harnessing nuclear fusion as an energy ...
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Who established that $K_e = \frac{1}{4 \pi \varepsilon _m}$?

Coulomb's Law states that : $$F_e = K_e\dfrac{q_1q_2}{r^2}$$ where $q_1$, $q_2$ are magnitudes of the two point charges, $r$ is the distance between them and $K_e$ is Coulomb's Constant (aka ...
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How transparency was explained by corpuscular theory and Young/Fresnel's wave theory

How did the light theories of Newton and Young/Fresnel explain the transparency of materials such as glass, or opacity of materials such as paper and wood? Newton's theory of light was largely based ...
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103 views

Which conception of a “machine” allows to call “mechanical” the new physics of the 17th century?

My questions deal more properly with pre-Newtonian modern physics in its Cartesian or Hobbesian versions. The word "mechanical" comes from a Greek word meaning "machine". However, the received ...
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43 views

Fresnel's partial aether drag hypothesis

In 1810, François Arago realised that variations in the refractive index of a substance predicted by the corpuscular theory would provide a useful method for measuring the velocity of light. These ...
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Where can I find Lagrange’s original equilateral triangular solution for arbitrary masses?

This answer to What kind of triangle is formed by three unequal masses in a circular restricted three body orbit? explains that In the Newtonian limit, an equilateral 3-body solution exists for any ...
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How has the degree of mathematisation in physics university education in the U.S. changed in the 20th century?

I'm mostly interested in the degree of mathematisation with which physics was taught. Intuitively, I believe to recall that Europe has had a long tradition of mathematical physics, while physics ...
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94 views

Quantum chromodynamics - an origin of the name

A theory of strong interaction is called quantum chromodynamics (QCD). Particles interacting strongly are supposed to have color charge, for example quarks appear in three "mutations" - red, green and ...
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Origin of Fourier Transform (1878)

I located Joseph Fourier's book, Analytial Theory of Heat (1878), but at first glance it looks like it is all about heat. What did Fourier call the Fourier transform? When did he first use it?
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How was a material independent temperature scale created?

Temperature measurements started with the developments of thermoscopes and thermometers. They were based on the fact that liquids in general expanded significantly on change in temperature (especially ...
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Was Joseph Priestley “isolated”

Joseph Priestley is often said to have discovered Oxygen, or not due to calling it Dephlogisticated air - depending on one's preference. However, regardless of this, it is often said in popular ...
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60 views

Did the mathematician Garrett Birkhoff ever work with or mention Feynman's path integrals?

Did Garrett Birkhoff ever work with Feynman's path integral? Did he ever work in his Many-Histories interpretation? Or at least, did he mention it in any of his articles?
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How did Newton prove his third law of motion?

I guess it is an experimental law, so what was the experiment?
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181 views

Natura non facit saltus (nature does not make jumps), who said that?

The sentence is Latin for nature doesn't make jumps. It refers to the fact that, in most physical processes, quantities vary continuously. The principle was used by Leibniz, Kant and Darwin among ...
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Use of kT for energy of a wave?

The energy of $\frac12kT$ for each degree of freedom of a particle from statistical mechanics was derived from particles, and yet Rayleigh and Jeans just nonchalantly said let's borrow this and apply ...
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What did people understand heat and temperature to be in Clausius' time?

I just took a read of Clausius' original writing from 1867 on the second law. He refers to the "unit of heat" as "that amount of heat which is required to increase the temperature of unit-weight of ...
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119 views

Did Heisenberg ever accept Schrödinger's formulation of quantum mechanics, or at least did he relax his negative views about it?

Both Heisenberg and Schrödinger found each other's way of formulating Quantum Mechanics quite repellent. My question is: Did any of the two change their views towards each other (specially Heisenberg)...
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111 views

Portrait of Stephen Butterworth

Does anybody know of a portrait of Stephen Butterworth (1885 - 1958), a British physicist?
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Historical accounts of a oft-cited quip by astronomer Walter Baade

I am looking for any documented, historical reference to an oft-cited humorous reply by German astronomer Walter Baade (1893 – 1960). After having asked if other astronomers were familliar with the ...
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Who originally worked out the magnetic field produced by a solenoid and toroid?

Although, it seems very easy to find the magnetic field produced by a solenoid or a toroid, all we got to do is to make a suitable an Amperian Loop and take the $\mathbf B$ out of the integral and so ...
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43 views

Lawrence and Segre: Further information about relationship

There is a oft-repeated story (https://en.wikipedia.org/wiki/Emilio_Segr%C3%A8) about Lawrence, upon discovering that Segre was legally trapped in the USA, unable to return to Italy due to fascist ...
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114 views

What made Newton realize that the law of gravitation was 'universal'? [duplicate]

Newton's law of gravitation operative near the earth is the same law causes the earth and the other planets to go around the sun and other heavenly phenomena. Was it a giant leap of faith by Newton or ...
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33 views

Did pre-Galilean astronomy inspire Mach's principle?

Was Mach, in his formulation of "Mach's principle," influenced by pre-Galilean astronomy, such as that of Aristotle in On the Heavens, where heavenly bodies influence terrestrial ones?
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22 views

What experiment proved that electric current is charge transport? [duplicate]

To my knowledge, neither Volta nor Ampere nor Oersted, the founding fathers of electric current, knew that current is the transport of charge. Who, then, and by which experiment, proved the nature of ...
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809 views

Who first solved the classical harmonic oscillator?

There is a question Who solved the quantum harmonic oscillator?, but not one for the classical oscillator. Wikipedia's article Harmonic Oscillator does not have historical information either. So who ...
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204 views

How did 19th century physicists do their undergraduate/graduate studies?

I have read that In 1847, he became aware of physicist James Prescott Joule’s argument for the mutual convertibility of heat and mechanical work and for their mechanical equivalence. We study ...
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46 views

Can you suggest good resources for reading about history of science especially physics? [duplicate]

I'm looking for good resources of history of sciences (especially physics) which cover history from the time of Newton and Galileo (or before them) till the modern physics world (21st century).
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Did James Clerk Maxwell derive the permittivity of free space from his “Maxwell's” equations or was the parameter already known by him?

My problem is my lack of knowledge on the historical development of the constant used for the permittivity of free space. I know instead of asking the question I should read Wiki on the history of "...
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198 views

Advance of the perihelion of Mercury

When I did my MSc in astrophysics back in '95-'96, I was told that there had been an attempt around the early 20th century to account for the advance of the perihelion of Mercury by altering the ...
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342 views

Who introduced the “dagger”symbol as conjugate transpose in quantum mechanics?

The $\dagger$ symbol is often used in quantum mechanics,and also often in general mathematics to represent the conjugate transpose operation.For Hermitian matrices we can write $$A^\dagger=A$$Who ...
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What exactly was Lagrange's “grave mistake” with respect to rotating bodies under hydrostatic equilibrium?

A comment below What would be different about satellite orbits if Earth were prolate? Would we have Sun-synchronous and Molniya orbits? got me reading Wikipedia's Jacobi ellipsoid which begins: ...
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57 views

Dirac and proton-electron annihilation

Wikipedia says: Robert Oppenheimer argued strongly against the proton being the negative-energy electron solution to Dirac's equation. He asserted that if it were, the hydrogen atom would rapidly ...
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1answer
93 views

What is the explanation of rope's strength in Galileo's Two New Sciences?

I'm reading Galileo's Two New Sciences. But as other Scientific Book it is hard. I am having trouble in First day, where SIMPLICO asks this question(Page 7): "But how can one make a rope one ...
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94 views

What did Hans Bethe think of von Neumann's quantum logic?

Nobel laureate Hans Bethe was a friend of mathematician-physicist John von Neumann, and he once said: "I have sometimes wondered whether a brain like von Neumann's does not indicate a species ...
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116 views

What is the history behind defining temperature as measure of hotness?

I know that when two bodies of different temperature are kept in contact "heat" flows from hotter body to colder. But how did anyone know that it is the "hotness" that flows, one could have said that ...
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1answer
56 views

When was spin of subatomic particles other than the electron discovered?

The idea of a spin angular momentum was first proposed in a 1925 publication by George Uhlenbeck and Samuel Goudsmit to explain hyperfine splitting in atomic spectra. At what time was it measured ...
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123 views

Einstein praising Sophus Lie

p. 153 of Raúl M. Falcón Ganfornina and Juan Núñez Valdés, “Mathematical Foundations of Santilli Isotopies,” trans. Alan Aversa, Algebras, Groups, and Geometries 32 (2015): 135–308. quotes (but does ...

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