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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3
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1answer
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Had Albert Einstein tried to use the Galilean transformation on Maxwell's equations before AE's Special Theory?
I am looking for what motivated Albert Einstein in the direction of his Special Theory. I have read that it is unclear if he was set on that path by the Michelson-Morley experiments. Was AE aware ...
3
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1answer
104 views
Are there any direct comments by Isaac Newton on Leibniz's living force / vis-viva?
The living force or the vis-viva is a quantity usually attributed to Leibniz (although there were a few other people who identified it as a conserved quantity in certain collisions earlier). Many ...
5
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1answer
134 views
Have there been instances in physics where different scientists have interpreted the same data differently? [closed]
Have there been instances in physics where different scientists have interpreted the same data differently? If yes, can you please give me specific examples and explain why one interpretation was ...
1
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0answers
55 views
Who first measured the increase of mass with speed?
Wiki (https://en.wikipedia.org/wiki/Electromagnetic_mass) says that:
Thomson (1893) noticed that electromagnetic momentum and energy of charged bodies, and therefore their masses, depend on the speed ...
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0answers
70 views
How did the US get enough U235 for "Little Boy"
The answer to a different question (Where did Fermi get the U235 for the first nuclear pile) about U235, was that Fermi used natural uranium for his reactor. This explains, in particular, the origin ...
3
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1answer
81 views
Is there a source for a footnote in *A Canticle for Leibowitz* about the definition of the electron, "Negative Twist of Nothingness"
In a French edition of Fiat Homo (first part of A Canticle for Leibowitz) I found the following footnote about the definition of the electron given by Brother Francis to another monk, namely “Torsion ...
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0answers
57 views
Who was the first scientist to give a formula for the probability density function of the position of a photon in the double slit experiment?
The double-slit experiment shows the fundamentally probabilistic nature of quantum mechanical phenomena. On Wikipedia one can read:
This type of experiment was first performed, using light, by Thomas ...
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0answers
26 views
Why is the magnetic force on a current-carrying wire sometimes called the Laplace force?
Living in the UK, I've been used to calling the force on a current-carrying wire in a magnetic field 'the motor effect force'. But I'm increasingly aware of another (less clumsy?) name for it: 'the ...
2
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1answer
86 views
Who introduced velocity potential?
Wikipedia cites John Anderson’s A History of Aerodynamics and says that velocity potential was introduced by Lagrange in 1788. However, I could trace it at least to Euler 1752, where he published his ...
3
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1answer
271 views
Who introduced gravitational potential?
Some sources say that gravitational potential was introduced by Lagrange in 1773, and others say that it was introduced by Bernoulli in 1738. I sifted through Daniel Bernoulli's Hydrodynamica (...
0
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0answers
55 views
How was it determined that charge and current were made of the same stuff?
Even in my earliest physics course we took for granted that charges are made of electrons (or their absence) and currents are due to the motion of electrons. But the electron is a very modern concept ...
6
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0answers
133 views
Why is it said that Marie Curie died due to her work but the same isn't said for Fermi?
I learnt in school that Marie Curie died from her work at 66 years. On the other hand, Enrico Fermi, who also handled a lot of radioactive substances died of stomach cancer at the age of just 53. It ...
0
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3answers
219 views
What was the first time that a Physical quantity was squared to describe a physical phenomenon?
When was the first time we see a square in an equation describing some physical effect?
Well, there is the area of circle (or square of course ...), but a circle area is not - in this question ...
2
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1answer
121 views
How did Heisenberg build the P Q matrix terms?
I learnt in some Wikipedia articles that the terms of the P and Q matrices designed by Heisenberg were composed of Fourier coefficients. Could you provide some explanation on how these coefficients ...
2
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0answers
90 views
de Broglie's conception of the electron
I've been working on de Broglie's thesis (English PDF, Original French PDF) for a course, and I've found something that's been bothering me. My training is in Physics, and so I'm not particularly ...
5
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0answers
121 views
What's the origin of the claim that a single uranium atom fissioning would release enough energy to visibly move a grain of sand?
There's a fairly widespread claim that the energy released by the fission of a single atom of uranium would release enough energy to make a grain of sand visibly jump. Richard Rhodes's The Making of ...
4
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0answers
108 views
Earliest measurement of proton's mass
I was looking for the earliest experiment or the paper which shows the determination of the mass of proton. In NIST CODATA, the mass of proton is listed as "1.672 621 923 69 x 10$^{-27 }$kg"....
3
votes
1answer
91 views
Ideas about the speed of light between Galileo and Romer?
I know that the great Galileo made no real progress measuring the speed of light -- he disappointingly suggested that it might be infinite. I read that he concluded (based on his attempts to measure ...
2
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0answers
165 views
Around 1904, did the scientific community take the atomic hypothesis seriously?
The time when Thomson discovered electrons, around 1897, what did the scientific community think about the atomic hypothesis? Was there a majoritarian consensus that matter is made of indivisible ...
2
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2answers
113 views
How accurate was the measurement of the period of Earth's orbit in the 19th Century?
There was a section on my textbook on history of theories of sun's energy source.
It talks about how the Meteorite Theory was dismissed, as it would decrease the period of Earth's orbit by 2 seconds ...
3
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0answers
109 views
Diffraction pattern of Michelson's echelon
Has anyone used Michelson's echelon (pictured below), a very famous type of diffraction grating in the 1920s? I am wondering how did the diffraction image look like from this type of transmission ...
1
vote
1answer
98 views
What was Einstein's first publication of the final form of general relativity?
What was Einstein's first published exposition of his final form of general relativity, be it a scientific article or a book?
I've been googling the answer for hours now, with no luck, really. The ...
13
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2answers
2k views
Who was the first to hypothesise that gravity from one mass causes the spacetime around another mass to curve?
Was it Einstein? Or was there someone before him to hypothesise this?
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0answers
75 views
Who introduced the difference between magnetic fields in matter? $\mathbf H$ vs $\mathbf B$
In magnetism, there are two different magnetic fields, that I will simply call $\mathbf B$ and $\mathbf H$. The distinction is not always clear. In experiments $\mathbf H$ is the applied field while $\...
14
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3answers
5k views
Historical example of research papers being misinterpreted due to poor wording and creating controversy?
Is there any example of major controversy in the scientific community caused due to poor wording and/or misinterpretation of words?
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0answers
75 views
Historical example of research papers being misinterpreted due to poor wording and creating controversy? [duplicate]
Is there any example of major controversy in the scientific community caused due to poor wording and/or misinterpretation of words?
2
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1answer
108 views
Who first proposed the idea of "resolution of the identity"?
Who first proposed the idea of "resolution of the identity" as used in the functional calculus of self-adjoint operators? Was it von Neumann?
In Japanese, it translates as "resolution ...
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0answers
46 views
Which scientist(s) first measured the elementary charge and how did they do it? [duplicate]
I would be grateful if anyone could shed some light on these questions.
Which scientist(s) first measured the elementary charge? If it wasn't measured in a straightforward experimental setting, and ...
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1answer
79 views
In physics, how are two quantities found to be proportional to each other? [closed]
For instance, force was discovered to be proportional to mass and acceleration.
How are these proportional relationships discovered and proven to be true?
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1answer
56 views
What is the difference between caloric and heat?
What is the difference between caloric and heat? Is there a difference?
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2answers
183 views
Roughly when did it become accepted by the western scientific community that human space flight could be possible in the future?
Safe human travel into space had to have become scientifically accepted as plausible long before any nations managed to successfully pull it off (and unsafe or one-way human travel likely earlier than ...
6
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0answers
90 views
What technology was used to determine the shape of the blackbody spectrum at the 19th century?
The shape of the blackbody radiation spectrum was known in the 19th century from experimental measurements, and before the theoretical discovery of Planck's law.
At those times, how did people manage ...
13
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12answers
6k views
Which physicists died very young or in a tragic way?
Inspired by Which mathematicians died very young or in a tragic way? , I wonder which physicists had similar fates.
A quick search lead me to Heinrich Hertz who died from a malignant bone condition at ...
5
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2answers
1k views
How did Stern or Gerlach, of Stern-Gerlach experiment, create individual silver atoms? How were they accelerated?
How, a century ago, could Stern and/or Gerlach KNOW that they had created single silver atoms?
How were they moved, or accelerated?
3
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2answers
167 views
How did Kirchhoff express his voltage law (KVL)
It is sometimes claimed that Kirchhoff's Voltage Law (KVL) is equivalent to the statement that a given electric field is conservative. Or, put another way, is is sometimes claimed that KVL is ...
2
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0answers
56 views
Since when is it commonplace to use conservation of energy for dynamics problems?
If I throw an object, I can derive its trajectory using the forces acted on it. I can also do the same using conservation of energy.
Since when is it commonplace to use conservation of energy for ...
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2answers
206 views
What was the decisive argument against Le Sage's theory of gravity?
Le Sage's theory described gravity by means of corpuscules, small particles pervading space that hit masses all around. Between two masses a shadow comes about. None of them are present there. Masses ...
3
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2answers
130 views
In Newton's cannon image, where do the shapes drawn into the sphere come from?
I find quite interesting the choice for the shapes drawn into the sphere that resembles continents.
Was this choice arbitrary or do we know if there is some justification behind it?
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7answers
7k views
Has there been an equivalent in physics to Ramanujan in maths?
Ramanujan's story is a well known story of the Indian young man who turned out to be a mathematical genius without a scholarly education. He was "discovered" by the mathematician Hardy at ...
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1answer
189 views
How come that the "heroes" in physics are gone?
I'm not sure if this question can be answered objectively but I still ask.
Once upon a time there were people like Galileo, Newton, Einstein, Feynman, Curie, Tesla, Dirac, Schrödinger, maybe Chopra, ...
2
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0answers
127 views
On the origin of "sandwiches" in quantum mechanics
The term "sandwich" and the verb "to sandwich" appear pretty common but informally in quantum mechanics. Generally when describing some kind of inner product of the form:
$$\langle ...
2
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2answers
285 views
Why is periodic motion always represented as a sine function
Why was periodic motion started to be represented as a sine function at the beginning? Is it because it is perhaps the simplest periodic function? Is there certainly any reason behind this ...
0
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1answer
116 views
Was Einstein's "Maschinchen" a predecessor of the photomultiplier tube?
Einstein once got involved in true experimental physics. That is, he designed his little machine (Maschinchen, in German, a word that makes me laugh; Einstein's Maschinchen...) to detect small ...
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0answers
47 views
How was the first calculation of the g-factor done?
Dirac said the magnetic g-factor (a measure of the electron's wiggling in a magnetic field) is exactly 2. Quantum field theory introduced a g-factor that diverged a bit from 2. It needs an increasing ...
2
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1answer
116 views
Earliest numeric value for helium D3 line
In late 1868, Norman Lockyer discovered the existence of the D3 emission line of helium in the solar spectrum. What was the earliest published example of a numeric value for the wavelength of this ...
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0answers
84 views
What was the attitude towards atoms around the turn of the nineteenth century?
Einstein invented, on his own, a statistical mechanics, presupposing the existence of atoms. I can't imagine he was unaware of the shortly-before-invented statistical approach by Boltzmann and others, ...
3
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4answers
397 views
Whatever happened to quaternions?
Quaternions were made up by Hamilton. They are an extension of complex numbers. It is said that he first introduced "3d tertions". He was thinking what the relation between i and j had to be ...
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0answers
48 views
Where there scientists before Einstein who viewed space(time) as being elastic?
Einstein was the first who saw spacetime as a mallable substance to be malled with mass. As far as I know there were no people who suggested such a view of spacetime before him. But I could be wrong.
...
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1answer
116 views
About Newton's apple
I read:
Suddenly – boink! -an apple hits him on the head. “Aha!” he shouts, or perhaps, “Eureka!” In a flash he understands that the very same force that brought the apple crashing toward the ground ...
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1answer
207 views
Why didn't the phase space formulation of Quantum Mechanics get the upper hand?
At university I learned quantum mechanics in or position or momentum variables. Later (in fact on this site), I learned about the phase space formulation in which both are used at the same time.
The ...