Questions tagged [physics]
For questions about the scientific discipline that concerns itself with analysing the laws of nature in full generality
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In Geiger-Marsden experiments how was charge of alpha particle and charge of gold atom found?
Here: https://en.wikipedia.org/wiki/Geiger%E2%80%93Marsden_experiments
Some calculations were done to show how JJ Thomson's model predicts alpha particles will be mostly undeflected by the gold foil. ...
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Need a reference for Euler's velocity initial condition for the wave equation
In DOI: 10.4236/ahs.2020.94019 235 Advances in Historical Studies, p.234
D’Alembert and the Wave Equation: Its Disputes and Controversies, or https://www.scirp.org/pdf/ahs_2020112716312281.pdf p.6 of ...
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In JJ Thomson's cathode ray experiment I need values for the electric field and magnetic field when net force on the cathode beam = 0
I asked here as well https://chemistry.stackexchange.com/questions/177889/in-jj-thomsons-cathode-ray-experiment-why-is-effects-of-gravity-on-electron-not
https://physics.stackexchange.com/questions/...
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2
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Who postulated the first Lagrangian for electrodynamics?
I am trying to find who first translated Maxwell's equations and Lorentz's force into the Lagrangian formalism. It seems a very straightforward thing to do if you know enough of electromagnetism and ...
- 2,688
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1
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Did Newton know about non-inertial frames?
When answering a Physics.SE question, I made a claim that Newton realized that $F=ma$ worked in some frames, which are called "inertial frames." Nowadays, we know that there are non-...
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Book on the evolution of Quantum Theory
Can anyone recommend some good book(s) on the Evolution of Quantum Theory, focusing on history, not necessarily on explaining the technical/math part?
The books I have read so far,
"Quantum: ...
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What was the last "hole" in the electromagnetic spectrum where amplified, tunable, narrow-band power couldn't be produced artificially?
We had radio amplifiers that could transmit powerful signals and those were pushed to microwaves. We had lasers that were originally natural transitions in solids and gasses but now tunable lasers go ...
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Did J. W. Gibbs “invent” Hilbert spaces before Hilbert formulated the notion of such spaces?
I was surprised to see a reply to a comment on his answer to a Quora question by a research mathematician claiming that Hilbert spaces were actually due to J. W. Gibbs rather than to D. Hilbert. The ...
2
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Onsager on phase transitions
Surely You're Joking Mr. Feynman has Feynman ascribing to Onsager the following quote (during the International Conference of Theoretical Physics in Kyoto, in 1953):
"We should tell Feynman ...
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Why was the Greek letter psi (Ψ) chosen to represent the wave function?
When I was reading, the question just popped into my head after noticing that the Greek letter ψ looks kind of like a wave itself. Stylized, they look even more wavy:
$$\Huge \Psi\;\Huge\psi$$
This ...
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Do gravitational waves hold the record of longest delay between prediction and confirmation under the same theory?
This question is similar to What was the longest delay between prediction and confirmation of a theory? but I want to frame it in a different way. I am looking for long delays between prediction and ...
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Technical papers or monographs without a single mathematical equation
Recently, I stumbled upon a historically important monograph on a technical subject, which explained complex physical phenomena without a single mathematical equation. I forgot the name of the author, ...
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Where did the popular idea of spacetime come from?
[This question is about popular conceptions and therefore goes into strange directions, don't get too shocked]
The notion of spacetime can be traced back to roughly the 18th century where some people ...
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108
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Reconstruction of Newton's axioms
Hilbert reconstructed Euclid's axioms. Is there an equivalent restructuring of Newton's axioms, or are they considered consistent?
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When were arrows first used to visualise vectors?
I guess the use of arrows to visualise vectors came before the general notion of vectors, so a more precise question is: when where arrows first used to visualise physical (or mathematical) quantities ...
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How does Legendre transformation in classical mechanics relate to Adrien-Marie Legendre?
I tried to look for the history of Legendre transformation, which transformed Lagrangian mechanics to Hamiltonian mechanics, usually formulated as
$$
\begin{cases}
p_i = \frac{\partial L}{\partial v_i}...
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3
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Why didn't Einstein propose any metric solution to his equations?
I've read about general relativity (GR) recently and something stroke me: Einstein came up with his equations in 1915, linking the metric of spacetime to the distribution of energy (more exactly, to ...
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Who found the formula for sequential Stern-Gerlach experiments and when?
Today we know that if you make sequential Stern-Gerlach experiments, where the magnetic fields are at an angle $\alpha$, then the formula for the ratio how the beam splits is
$$p_{1}=\cos^2 \bigg(\...
2
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1
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104
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How was light polarization interpreted when first discovered?
Malus first discovered light polarization just before 1810, but Maxwell's equation stuff came around 1860s. How was polarization interpreted before the EM theory?
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What were the initial physical applications of vector calculus such as curl, div, circulation, and flux?
In what context where vector calculus concepts, such as:
Circulation
Flux
Curl
Divergence
first developed? I had assumed they were developed first in fluid dynamics, since the flow of water is ...
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When was Galileo's De Motu (Antiquiora) Made Available to the Public?
This question is in regard to Galileo's early writings on motion titled De Motu (On Motion) or De Motu Antiquiora (Older Writings On Motion).
It is understood that Galileo never published this ...
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Did Wheeler and Feynman said that vacuum zero point energy could boil the oceans?
Following on this Were Feynman diagrams motivated by the cosmological constant problem? and this Who was the first to estimate the vacuum energy discrepancy by 120 orders of magnitude? I found a ...
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Were Feynman diagrams motivated by the cosmological constant problem?
Sean Carroll, while speaking about the history of quantum field theory, has said a couple of times (without being completely sure of its factuality) that Richard Feynman was motivated by his trying to ...
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What is the origin of the "red, green, yellow" quark color convention?
In physics, quarks come in one of three color states, usually chosen to be called, "red", "green", and "blue". However, because these are just labels, there are other ...
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What values of Avogadro's Number did Jean Perrin come up with?
I am currently plundering the contents of the $1969$ reprint of the 2nd edition of Data and Formulae for Engineering Students published by Pergamon International (authors J.C. Anderson, D.M. Hum, B.G. ...
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How the concept of Momentum was discovered?
As we already know that the concept of Momentum was discovered before Newton discovered his laws of motion, but my question is $\rightarrow$ How they discovered the relationship p=mv without knowing ...
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28
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Early sources for surface and bound charges in polarization
I am looking for early sources (references) to the analysis in electrostatics where the polarization vector is rewritten in terms of bound charges and a surface polarization charge.
In terms of what I ...
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40
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Early triboelectricity
I am looking for good sources to quote for early work on triboelectricity. I already have the standard ones, e.g. Benjamin Park (1898) "A history of electricity..", Roller & Roller (1953)...
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133
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Did Heisenberg say free will could arise from quantum probabilistic mechanics?
I see this view attributed to him a lot during Twitter debates but I never found the source for it
does anyone know if Heisenberg actually held this view/suggested it?
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Who was the first to estimate the vacuum energy discrepancy by 120 orders of magnitude?
Apparently, this discrepancy is one of the "worst predictions" in the history of science. Clearly the vacuum energy calculation depends on many approximations and it is not clear how it ...
- 2,688
4
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1
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How did Kelvin square his low estimate of the age of the sun with the geological evidence?
Kelvin famously disputed geological estimates of the age of the earth because he said gravitational collapse couldn’t fuel the sun long enough. But even if gravitational collapse, not fusion, had been ...
3
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1
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112
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Why did Maxwell predict radiation pressure?
I know that Kepler thought based on comet tail that light might exert pressure (although is the Solar wind not also involved?) but did Maxwell's prediction stem from newer observations or from perhaps ...
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1
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How do I find a list of all works published by a Physicist?
So far I've been checking Wikipedia listings, the university websites of the physicist in question, some databases like OA.mg, and literature searches at university websites. But it’s all scattered, ...
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Why did systems theory never gain popularity?
Briefly from wikipedia,
Systems theory is the interdisciplinary study of systems, i.e. cohesive groups of interrelated, interdependent components that can be natural or human-made. Every system has ...
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1
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Light propagated instantaneously rather than gradually
In the following paper from I. Bernard Cohen, "Roemer and the First Determination of the Velocity of Light (1676)" published on Isis (1940):
Can be read:
explaining that the delay would ...
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Where does motion happen for Galileo?
I have a question from the first two paragraphs of this answer:
Newton's idea of absolute space simply appeared as an answer to the following question: What is an inertial system? Saying that an ...
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0
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73
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Origins of a "Theory of Everything" in physics
In physics, is it possible to trace the history of the idea that the known forces (electromagnetic, weak, strong and gravity) should be unified in a "Theory of Everything"? Would it go back ...
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What are some physicists that wrote literary works?
As usual when I see an article about asking about mathematicians, I cannot help to ask what about physics? Inspired by Literary works authored by mathematicians what are some physicist that also were ...
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What is the etymology of the term space-time?
I'm looking for the earliest references to the word space-time (in the modern sense), in any language.
The first references would likely be in German, as Raum-Zeit or Raumzeit.
Of course, H. Minkowski ...
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What led to people looking at phase spaces?
In basic physics, the emphasis is calculating total forces, and going from that to the position function of the body as a function of time by integration. Now, from this prespective, how did people ...
2
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Archimedes' lever and the concept of work
Do I understand correctly that Archimedes was not familiar with the concept of work and hence attributed mechanical advantage to a lever's ability to create force rather than understanding that the ...
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0
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What are some outdated concepts in general relativity?
Inspired by outdated concepts in special relativity such as When and why did the concept of relativistic mass become outdated? and Special relativity and imaginary coefficient of the time coordinate, ...
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Original description of point sources and point spread functions
I already asked this question in the Astronomy community, but there it was recommended to me to also try my luck here.
I would like to know the original description of point sources and point spread ...
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On early US patriotism to choose quark color charge labels
Sean Carroll has a video about gauge theory (2020) in his series about Greatest Ideas of the Universe, where he claims that early in the development of quantum chromodynamics, some physicists tried to ...
- 2,688
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The etymology of "radio waves"
The word "radio" originates from "radius", which in turn came from "ray". That's why "radius" means any line from a central focal point to any directions.
...
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1
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Were scientific discoveries ever inspired by art?
We can often see art that is influenced by science, be it in paintings, music, novels or movies. But has any idea from the arts ever influenced a scientist to come up with a new discovery or idea?
2
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How did Aristotle explain the motion of living things moving by themselves, and falling of objects, with his hypothesis of all motion needing a cause?
Aristotle (384 BC – 322 BC), a pioneering, iconoclastic, and brilliant ancient Greek philosopher, made the observation in his writings that the long term stable state of objects is at rest, that ...
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Poisson's laws for adiabatic processes
I've been reading about Thermodynamics lately. The set of equations satisfied in an adiabatic process (and also more generally in polytropic ones) is:
$$p_1V_1^\gamma = p_2V_2^\gamma$$
$$T_1V_1^{\...
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0
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Understanding how Stern-Gerlach tests Bohr-Sommerfield Hypothesis
I am trying to get to the bottom of a few things in the Stern-Gerlach experiment. First, on wikipedia, it says
The Sommerfeld model predicted that the magnetic moment of an atom measured along an ...
5
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0
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On Bryce Seligman DeWitt's Name Change
Weinberg, in his memoir on Bryce Seligman DeWitt (available at https://www.nasonline.org/publications/biographical-memoirs/memoir-pdfs/dewitt-bryce.pdf) states that
In 1950 two major but totally ...
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