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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8
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144 views

Landau doubting conservation of energy---and what followed

When the original beta decay experiments seemed to suggest that energy was not a conserved quantity, Landau (among others) proposed that energy conservation was a statistical law rather then a ...
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131 views

Who first discussed the Lorentz force with respect to special relativity?

The fact that a Lorentz force in a reference frame 1 can become a Coulomb force in another reference frame 2 has always astonished me, especially because the velocities involved are really small. I ...
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116 views

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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86 views

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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1k views

Why Doesn't Einstein Get More Credit for Being the Father of Quantum Mechanics?

I'm not simply referring to the notion that Einstein treated the discrete emission and transference of energy (and matter) as "real" physical phenomena, but rather his major continuous role in the ...
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161 views

How did Maxwell conclude that $\frac{\partial\bf E}{\partial t}$ was necessary to complete $c^2\nabla \times \bf B= \frac{\bf J}{\epsilon_0}\;?$

As we know $$c^2\text{curl}\;\bf B= \frac{\bf J}{\epsilon_0}$$ is incomplete & in many cases like capacitor give contradictory result against Law of conservation of charge. As Feynman writes; ...
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Physics Curricula of 19th Century French Universities?

What were the physics curricula for 19th century French universities? I am looking for something akin to this distribution of courses at the École Polytechnique, but for other French universities, ...
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504 views

How did Einstein know tensors would be needed in the EFEs?

I'd really never studied tensors until I started studying the Einstein Field Equations. Since then, I have realized they are fairly common tool in physics and pretty basic to understanding many areas. ...
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73 views

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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69 views

“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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56 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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143 views

What happened to the undergrad students who attended the Feynman Lecture Series in 1961-63?

Note: This question was originally asked here, but I was wondering if I could get further clarification as this has truly intrigued me. In the academic years of 1962-2 and 1962-3, Richard Feynman ...
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105 views

Did Paul Dirac believe in multiple universes?

Prominent physicist Paul Dirac proposed a hypothesis that said that constants and laws of physics would evolve with time into different constants and laws of nature. This hypothesis was used by ...
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1answer
127 views

Did old Crookes Radiometers ever have a pair of terminals?

This is a question about old physics lab equipment. This and this question led to the question in SciFi SE Crookes Radiometer at the end of a telescope in old movie scene, something about a comet? ...
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96 views

Who was the first to use the term field in physics?

Faraday, after drawing his lines of force in 19th century, is normally credited as the first to use the term field in physics. But... ... was not the term field used in the context of gravitational ...
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109 views

During the development of QFT was this theory actually used to build any invention like the MRI?

I have always wondered if the equations of quantum field theory were actually ever used in the production of some invention or device other than needed to make predictions about the Standard Model of ...
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1answer
209 views

Did Einstein ever refer to the coordinate speed/velocity of light?

In modern parlance we talk about two different speeds of light in general relativity. We distinguish between the local speed of light, which is always $c$, and the coordinate speed of light, which can ...
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45 views

Different versions of mass during early years of special relativity

My question is basically about four different versions of mass from the early years of special relativity when the concept of relativistic mass was acceptable. I'd appreciate it if you try to keep ...
3
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1answer
86 views

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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58 views

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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191 views

Identification of scientists in de Gennes book

Petit Point: A Candid Portrait on the Aberrations of Science is a charming book written by the French physicist Pierre-Gilles de Gennes containing short essays on some of the prominent scientists that ...
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36 views

Looking for references to an experiment on the evaporation rate of water in sunlight

I remember reading a long time ago about some experiments measuring evaporation rate of water in large open containers (tubs) sitting on open ground. It was a simple experiment, each day the water ...
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192 views

Speed of light in aether

I've been recently reading about the famous Michelson-Morley experimental attempt to detect the Earth motion with respect to the aether. According to Wikipedia, Michelson initially made a mistake ...
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683 views

Why were the Nobel Prize in Physics not awarded in 1916, 1931, 1934, 1940, 1941, and 1942?

I only found the following at the Nobel Prize webpage: Why were the Nobel Prizes not awarded in those years? In the statutes of the Nobel Foundation it says: "If none of the works under ...
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142 views

What was Einstein's contribution to the Einstein-Podolsky-Rosen (EPR) paper?

Do we have any insight or document into theoretical development of the EPR papers both in terms of math, ideas and anything related to actual physical problem. I know that Einstein didn't write the ...
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107 views

Who first noticed violation of aufbau principle of elements like Cr, Cu, Pd, Au, and how?

It is often referred to as 'anomalous electron configurations' or 'unusual order of filling of orbitals' of a few elements e.g. Cr, Cu, Nb, Mo, Ru, Rh, Pd, Au etc.
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320 views

What was the need for Lorentz transformation in pre-relativity period?

Why was it necessary for the velocity of light to be invariant between different inertial frames and hence what was the need for Lorentz transformation when it was believed that velocity of light was ...
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70 views

What is the first effect demonstrating the importance (or existence) of quantum coherence?

As far as I know, in the old quantum theory, a system can only reside in a stationary state. There was no Hilbert space, and no linear superposition. Or, a system cannot be simultaneously in two ...
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364 views

Who introduced the creation and annihilation operators for the harmonic oscillator?

Or who first solved the harmonic oscillator in the algebraic method?
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72 views

Did the concept of the Dirac Sea influence the development of semiconductors like the transistor?

Dirac (1928), (http://rspa.royalsocietypublishing.org/content/royprsa/126/801/360.full.pdf) explained the negative-energy solutions of his equations as holes in a sea of electrons. The concept seems ...
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96 views

Are Brillouin's papers translated into English?

I mean the Brillouin in the WKB method. I want to read his original paper. But it is in French. Is it translated into English? It should be.
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204 views

In which paper did the typical textbook diagrams of the Millikan experiment appear the first time?

There are two typical visualizations for one of the results of the Millikan oil-drop experiment to illustrate that only integer multiples of some elementary charge occur in nature. The first one is ...
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47 views

Was the wide use of mercury in experiments in the 19th century related to alchemy?

We know that Newton's hair samples showed high level of mercury and of course he used mercury like crazy in his alchemy experiments (as did many/all alchemists not just in the west but also China) and ...
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49 views

How did Millikan consider utilizing oil to help determine the charge of the electron?

Robert Millikan's oil drop experiment help to find the charge of electrons using oil. An x-ray was aimed at the oil drops to give them a charge, and the droplets were attracted to the negative plate. ...
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49 views

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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79 views

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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120 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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69 views

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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30 views

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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102 views

Feynman's statement about the importance of basic science

I remember reading in the line that Feynman saying if the best technicians were tasked to build a radio they would make longer and thicker cables and transfer message but it took a physicist to ...
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57 views

Did Wheeler ever propose the existence of a multiverse containing parallel simultaneous universes?

It is known that the physicist John Archibald Wheeler proposed the existence of a multiverse in the form of a set of cycles of Big Bangs and Big Crunches (Cyclic/Oscillatory Multiverse Model). But I ...
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60 views

How did Gibbs discover Gibbs entropy?

I have read and I think that I agree with the idea that if we have to choose probability distribution for an unknown system then it is a good idea to choose a distribution that has the least bias. I ...
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152 views

Who discovered Maxwell-Faraday equation, $\nabla\times E=-\frac{\partial B}{\partial t}$? Was it Maxwell or Neumann?

I have been trying to find out who discovered Maxwell-Faraday equation, $\nabla\times E=-\frac{\partial B}{\partial t}$. Was it Maxwell himself, or was it Franz Ernst Neumann who derived it? The ...
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96 views

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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128 views

Who first noted the connection between Heisenberg's Uncertainty Principle and the Fourier Transform?

This is a question about the history of Quantum Mechanics. Who first noted the connection between Heisenberg's Uncertainty Principle and the Fourier Transform?
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68 views

Why was F. W. Lanchester's first aeronautical paper rejected by the Physical Society?

Lanchester was arguably the first to somewhat accurately describe the physical mechanism for the generation of lift. In 1894, the Birmingham Natural History and Philosophical Society read his paper, ...
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321 views

The Pedagogy of Physics — Bob and Alice?

It seems that almost every where that physics is taught, in particular teaching relativity or quantum phenomena, that examples or demonstrations using persons Bob and Alice is a common tradition. ...
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208 views

Is it true that Johannes Kepler thought that the earth was hollow?

I was researching a little about the hollow earth theory, I know that many Scientist's back up this theory, namely Euler and Edmond Halley. I would like to know what was the theory that Johannes ...
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76 views

What is the difference between chemico-chemists and physico-chemists according to Van't Hoff?

“Whereas the chemico-chemists always find in industry a beautiful field of gold-laden soil, the physico-chemists stand somewhat farther off, especially those who seek only the greatest dilution, for ...
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49 views

Determining the temperature of a remote star by using the black body radiation formula

I am new to astrophysics. There is a question about the celebrated Harvard classification. Can people at 1900 determine the temperature of a remote star using the black body radiation formula? I ...