Questions tagged [history]
History questions are welcome on this site whenever they have any bearing on our modern understanding of physics. However, if a question has only minimal or null bearing on our current understanding, or it specifically requires a historian's skills, toolset, and mindset to answer, then it should be migrated to the History of Science and Maths site. See the FAQ on Meta for more information.
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Story about a mathematician, a dinner party, and the three-body problem
I remember dimly hearing a story, coincidentally also at a dinner party, and I was trying recently to track the details down with no success. I was hoping someone here might have also heard this story ...
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Why didn't we change the conventional direction of current after discovering electrons? [closed]
The direction of current is taken to be opposite to that of the flow of electrons, due to the established convention that current is in the direction of the flow of positive charges. My question is ...
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How is the magnetization $M$ of a material measured?
In a linear material under the influence of an external field $H$, magnetization $M$ is given by
\begin{align}
{\bf M} = \chi {\bf H},
\end{align}
so that the total field inside the material is ${\bf ...
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Why was the neutrino thought to be massless?
Wolfgang Pauli once said (regarding the neutrino):
I have done a terrible thing. I have postulated a particle that cannot be detected.
Why did he figure it couldn't be detected? Was this because he ...
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Why does the metric system use the Celsius scale rather than the Fahrenheit scale?
Part of why I ask this is because the Fahrenheit scale has a higher degree of precision than the Celsius scale. And the Kelvin scale could just as easily been adapted to be an extension of the ...
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Graviton-graviton scattering in tree level. Based on a talk by Bryce DeWitt
In this talk given by Bryce DeWitt, at page 6 he mentions a problem he gave to one of his PhD students. The problem is to compute the graviton-graviton scattering amplitude in tree level approximation....
CommunityBot
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Is it true that Schrödinger wrote his Schrödinger Wave Equation from his mind? [duplicate]
My physics teachers told me that there is no derivation of the Schrödinger Wave Equation and that Schrödinger actually wrote this equation from nothing. He wrote it from his mind. Even in my book ...
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What is the proof of Bohr's quantisation rule? [duplicate]
In his atomic model, Niels Bohr proposed that electrons can be present only in those orbits where their angular momenta is an integral multiple of $\frac{h}{2π}$. That is
$mvr=\frac{nh}{2π}$, where $n=...
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Which paper introduced the concept of the "Bloch sphere"?
Everyone loves Bloch sphere, but which paper of Bloch was it introduced? The Wikipedia article on Bloch sphere (here), as of 17/May/2021 links to this paper of Bloch “Nuclear Induction” but it doesn’t ...
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What is the exact definition of the Universal Gas Constant $R$? One that gives the reason for every formula that has the idea of this constant
We find that $R$ can be derived in many different ways through various relations. Its born out of the concept of an Ideal Gas. However what definition can clearly justify all of the relations based on ...
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Slang: "finite value" meaning non-vanishing. Historical reasons behind this [duplicate]
Is any way to sort out the disciplines of physics where one understands under "finite value" a value that cannot be zero?
Is any historical justification for this contradictory terminology?
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Why are Maxwell's equations correct and not Newton's laws of motion?
In many books, while introducing Special relativity it is shown that Maxwell's equations are not consistent with Galilean transformations. So either Galilean transformations (and consequently Newton's ...
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Why is thermodynamics beyond doubt? [duplicate]
Eddington once gave the following quote:
The law that entropy always increases, holds, I think, the supreme position among the laws of Nature. If someone points out to you that your pet theory of the ...
rob♦
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Positron discovery
I was reading about Carl David Anderson's discovery of the positron and I have a question.
I understand why it was classified as positive electron (due to its curvature direction and amount of the ...
- 202k
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Lagrange equation 1788, and Hamilton principle 1834
Lagrange's equation and Lagrangian and derived in 1788. It is different from Newtonian mechanics view because Newton emphasizes the external force acts on the body. But the Lagrange's. view is that ...
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Were Kepler's Laws of Planetary Motion the first formal definition of an ellipse?
It seems to me that Kepler's Laws necessitate some definition of an ellipse in terms of a coordinate system. I am wondering whether Kepler's Laws mathematically defined what an ellipse is, or if he ...
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Problem of infinities in QED
Other than Renormalization what were the other approaches taken to solve the problem (by physicists of that period)? Why were they not as successful as Renormalization?
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What are the basic principles of experimental electromagnetism? [closed]
I want to learn about experimental physics in the context of electrodynamics and electrostatics. Basically I'd like to know how we are able to measure different quantities in this field (electric ...
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Difference between action-at-a-distance and a field according to Maxwell?
My question is more on a historical note that involves Maxwell’s equations. Besides the information that I have obtained from textbooks, I am mainly getting it from History of Maxwell's Equations and ...
CommunityBot
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How did Chadwick determine the speed of protons?
Chadwick, or perhaps one of the previous scientists who were working with the neutron experiment were able to determine the velocity of the protons ejected from the Paraffin wax.
I thought that the ...
rob♦
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What motivated Einstein to formulate general relativity?
I never really fully understood what motivated general relativity or why the Newtonian concept of gravity was considered problematic.
One thing I always hear is that it is because it doesn't address ...
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What's the significance of the nickel crystal in the Davisson and Germer experiment?
Davisson and Germer, in 1927, conducted an successful experiment to prove the existence of matter waves. What's the meaning of using the nickel crystal? I mean, why didn't they use any other materials?...
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Did Galileo offer an explanation why his law of falling bodies is independent of mass?
Naively, (and endorsed by Aristotle) one expects heavier things to fall more quickly, Galileo Galilei showed in the early modern period, that in fact this is not correct, and that in fact how they ...
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How did the concept of work come into existence? [closed]
Well this is really a silly question. However I am curious to know about this topic.
Concept of each of the quantities discussed in physics have come into existence based on some basic human thoughts. ...
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Did Penzias and Wilson really make a *picture* of the CMB?
Did Penzias and Wilson really made a picture (graphical picture of a sky map using a computer) of the CMB, as stated on the web, or is it completely wrong ?
Indeed, If I consider what they say here :
...
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Which were the standard undergraduate electromagnetism textbooks before Griffiths?
I am curious about the books that were the standard undergraduate electromagnetism textbooks in the 1950s and 1960s before Griffiths took over in the 80s.
Any resource recommendation would be welcome, ...
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Why was the AC Stark effect only discovered after the laser was invented?
I was reading a paper about the theory of the AC Stark effect, and I was struck by the following assertion:
For instance, the first observation of the AC Stark effect initiated by the laser radiation ...
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How was the superconducting order parameter discovered?
Just wondering if anyone knows the history behind this discovery? The BCS mean field theory suggests a breaking of our $U(1)$ symmetry; hence, a complex order parameter makes sense in that regard. How ...
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Why did the ancients fail to discover that the Earth orbits the Sun? [closed]
The ancients observed that the Sun and the 'fixed' stars rotated about the Earth. They were also aware that the Earth was spherical. They performed many astronomical measurements on the planets - ...
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Reference for Galileo's Law of Motion
It is stated in some places that one of Galileo's laws of motion is that two objects in free fall in a local gravitational field with different densities will hit the ground at the same time in a ...
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Why wasn't the meter defined using a round-number fraction (like 1/300 000 000) of the distance travelled by light in 1 second?
We know that 1 meter is the distance travelled by light in vacuum within a time interval of 1/299,792,458 second. My question is why we didn't take a simpler number like 1/300,000.000 or why not just ...
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How were the RGB Color Matching Functions established from 380 to 436 nm?
I have been reviewing how RGB color matching functions were formed, and I seem to be missing an aspect. The three primary monochrome lights used to generate a color like the target color are roughly ...
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A mathematical step done by Schrödinger in his solution to the hydrogen atom I need clarification on [duplicate]
in his paper "Quantisierung als Eigenwertproblem" he begins by introducing the Hamilton-Jacobi equation:
$$H\left (q,\frac{\partial{S}}{\partial{q}} \right)=E\tag{1}$$
such that $S$ is ...
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What is the inconsistency between Maxwell's electrodynamics and newtonian mechanics?
As far as I understand, when a modification of a theory is made it is because some observation required this modifcation. Quantum Mechanics is a nice example of that: observations of microscopic ...
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The history of Ampère's circuital law and Ampère's force law
How I know and read in the Internet that Ampere realized that two current-carrying wires can exert force on each other. Ampere's force law is:
$$d^2\vec{F_{21}}=-\frac{\mu_0}{4\pi}i_1i_2\frac{\hat{r}}{...
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Why was Einstein wrong about black holes?
In 1939, Albert Einstein published a paper entitled "On a Stationary System with Spherical Symmetry Consisting of Many Gravitating Masses." In it, he considers the problem of whether it is ...
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Who invented the term "Coulomb logarithm"?
Who is the author of the term "Coulomb logarithm"? In fact, Coulomb logarithm was computed by Langmuir in his paper of 1928 where the term "plasma" was introduced into physics, but ...
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What is a good book which contains all details of history of special relativity?
I am looking for a book which contains all the details of the history of special relativity.That means,I want to know about all those experiments like Michelson and Morley's due to which aether theory ...
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When was the phrase "beta function" of renormalization first used?
My question is a historical one: when was the phrase "beta function", as it pertains to the renormalization-group equations, used in physics? I am talking about this beta function:
$$\beta_g\equiv \...
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The light of speed and 24 hours
The notions of meter and second had been created much earlier than the speed of light was calculated. The speed of light is $299792458 ~ \text{m/s}$, i.e. it is really close to $300 ~000$ km/s. Also, ...
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Book on historic experiments
I am looking for a book which describes in a detailed way the most important experiments in the history of physics.
I was googling for it but could not find a satisfactory result. Either the books are ...
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Why did the scientific community stop using hydrogen as the main measure for the atomic mass unit?
The only thing I could find is that the community switched form one hydrogen atom to 1/16 of Oxygen-16 (which they thought to be the only isotope that exists at time because they had no concept of ...
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Did Victor Hess discover cosmic rays directly, or muons with his gold-leaf electroscope?
Most histories just mention cosmic rays themselves, but I also read that cosmic rays themselves rarely make it far into Earth's atmosphere, and it is usually muons, (or tauons or electrons) detected ...
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Existence of atoms - Einstein or Smoluchowski
When Einstein's seminal work on Brownian motion is discussed, Smoluchowski's name often comes up as having derived more or less the same results as Einstein, but from the perspective of kinetic theory....
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History of Principle of Least Action [closed]
I am interested in how Lagrange came up with Principle of Least Action.
Is it derived from some experimental data or by mathematical deduction? And how? Either seems hard.
I hope this might ...
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Who predicted the existence of the muon neutrino?
The Wikipedia article on the muon neutrino says:
The muon neutrino is a lepton, an elementary subatomic particle which has the symbol $\nu_\mu$ and no net electric charge. Together with the muon it ...
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What was the historical motivation for introducing the concept 'gravitational potential'?
As a high school physics teacher, I like to motivate all concepts and terminology with how they were first developed historically. Recently I did some research on the motivation behind introducing the ...
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What Did the Michelson-Morley Experiment Say about the Speed of Light? [closed]
In the quotation below, does Banesh Hoffmann, Einstein's collaborator, admit that originally ("without recourse to contracting lengths, local time, or Lorentz transformations") the Michelson-...
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Who discovered the speed of light is constant?
As we know that Michelson & Morley's experiment was not able to detect any effect of Aether on the motion of light, but if we follow the classic mechanism of law of motions as peoples do at that ...
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Force inversely proportional to the squared distance
Newton's law of universal gravitation:
"Newton's law of universal gravitation states that every point mass in the universe attracts every other point mass with a force that is directly proportional to ...
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