Questions tagged [physics]
For questions about the scientific discipline that concerns itself with analysing the laws of nature in full generality
794
questions
2
votes
1
answer
375
views
Who is the Westphal behind the Mohr-Westphal specific gravity balance? And how exactly did he improve on Mohr?
I'm a Spanish Physics undergrad, and I was writing a report on an experiment we did on the lab, in which we had to measure a solid's density using the so-called Westphal balance (aka Mohr balance, and ...
2
votes
1
answer
292
views
Why not proton volt instead of $eV$?
Why is eV used instead of proton V even if they would
give the same value?
I have this view: from electrochemistry's Faraday's law,
scientists first calculated the charge of an electron. Then,
they ...
- 225
2
votes
1
answer
230
views
In explaining photoelectric effect, why is photon quantized and not energy levels of electrons?
Einstein explained the dependence of stopping voltage on photon wavelength by quantizing energy of photon and in his model increasing the intensity will increase the number of photons keeping the ...
2
votes
1
answer
107
views
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. ...
- 43
2
votes
1
answer
134
views
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?
- 23
2
votes
1
answer
161
views
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. ...
- 1,247
2
votes
1
answer
95
views
History of determining the specific charge of the electron by balacing electric and magnetic forces
Nowadays is a well known high school or undergrad lab experiment to determine the specific electron charge by using a Wien-filter setup as described for example here.
Up to now I thought that this ...
- 191
2
votes
1
answer
169
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 ...
- 21
2
votes
1
answer
126
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 ...
- 116
2
votes
1
answer
165
views
How did Newton originally formulate the Law of Cooling?
I am searching for Newton's original formulation of the Law of Cooling. In his article (p.140-143), Newton said:
"For the heat which the hot iron communicates in a given time to cold bodies ...
- 41
2
votes
1
answer
360
views
Who is the father of fiber optics?
Here Wiki says Narinder Singh Kapany
is "father of fiber optics". Here source
says Charles Kuen Kao is "father of fiber optics".
Who is the father of fiber optics: Charles Kuen Kao ...
- 21
2
votes
1
answer
112
views
What is the name of the "largest complete history" of physics?
Somewhere in the world is housed what is thought to be the largest complete history of physics. I recall it being of some ridiculous length, something like hundreds or thousands of volumes. I cannot, ...
- 259
2
votes
1
answer
221
views
Is string theory today facing the same backlash that atomic theory faced during its inception?
I read in this Quanta article that although many critics say that it is far removed from nature, it has developed many powerful tools. Furthermore some don’t care if it’s a theory of everything and ...
- 121
2
votes
1
answer
249
views
Are Wheeler's It from Bit/Participatory Universe and the Multiverse related?
Could I ask you for the relation between Wheeler's ideas and the multiverse? Do you know if these are related?
I ask you this because I found this very interesting article written by Kip Thorne with ...
- 21
2
votes
1
answer
140
views
Did Cyrano de Bergerac's space ship have retro-rockets?
In this answer I cite and quote some surprising information; that the real Cyrano de Bergerac (not the one in the play) had written of using a rocket ship to go to the Moon circa 1650.
As strange as ...
- 2,163
2
votes
1
answer
755
views
Why are microcanonical, canonical and macrocanonical ensembles called that way?
In statistical mechanics, why microcanonical, canonical and macrocanonical ensemble are called that way?
Is there any reason according to the size of the system they can describe properly ( I don't ...
- 123
2
votes
1
answer
139
views
First descriptions of ultrastatic spacetimes?
What's the first appearance of ultrastatic spacetimes (that is, spacetimes with a metric of the form $ds^2 = -dt^2 + h$, with $h$ a Riemannian metric)? The oldest reference I can find on the topic is ...
- 865
2
votes
1
answer
282
views
How could Huygens have solved the tautochrone problem before Newton's theory of gravity and equations of motion?
In this answer to a question of mine on the stackexchange physics site, I learned about the tautochrone problem. Apparently it was solved by Huygens in 1659, which is before Newton's work on mechanics....
- 129
2
votes
1
answer
124
views
When was the quantization of spin discovered? [duplicate]
When was the fact that a spin could only have values S = n/2 derived? I cannot find any source that says when.
- 161
2
votes
1
answer
368
views
What is meant by higher order infinitesimals in the works of Galileo and Cavalieri
According to Boyer, Salviati introduces the idea of a higher order infinitesimal on the “third day” in Galileo’s Two Chief Systems of 1632. They are introduced in order to counter Simplicio’s ...
- 6,859
2
votes
1
answer
703
views
Who discovered diamagnetism first?
Ferromagnetism is everyday life.
Paramagnetism is not rare.
But diamagnetism is rare and weak.
So, who first discovered diamagnetism? in which material?
- 909
2
votes
1
answer
107
views
How did each base quantity get its name? [closed]
I've tried searching everywhere, but I can't seem to find anything related to how the quantities got named!
Base quantities:
Mass
Distance
Time
Temperature
Electric current
Quantity of a substance
...
- 31
2
votes
1
answer
130
views
Were Feynman diagrams important for the creation of the electroweak theory?
Feynman diagrams representing the interactions of subatomic particles were introduced by Richard Feynman in 1948. The first published Feynman diagram appeared in Physical Review in 1949.
Did Feynman ...
- 386
2
votes
1
answer
255
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 ...
2
votes
2
answers
232
views
Where does the prefix "super" from "supersymmetry" come from?
Where does the prefix "super" from "supersymmetry" come from?
- 121
2
votes
1
answer
294
views
Abraham's electromagnetism book and its story
Max Abraham is well known for his electromagnetic mass theory, and his book Theorie der Elektrizität is said to be read widely around 1900. I am trying to find this book, but the editions look like a ...
user2831
2
votes
0
answers
135
views
Origin of the concepts of Stress and Strain
Background & My research
So, I recently studied about the concepts of Stress and Strain in my high school physics classes and wanted to know about the history behind the origin and emergence of ...
- 215
2
votes
0
answers
83
views
History of logarithmic potential
I have some historical questions in connections for the notes to a book I am writing.
Who the first person to discover that the Coulomb potential in two dimension is $\log(|x|^{-1})$, equivalently ...
- 121
2
votes
0
answers
71
views
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 ...
- 397
2
votes
0
answers
362
views
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 ...
- 3,897
2
votes
0
answers
118
views
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 ...
- 397
2
votes
0
answers
34
views
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 ...
2
votes
0
answers
138
views
How futuristic was the use of a laser in 1964's "Goldfinger"?
In the 1964 adaptation of the James Bond novel "Goldfinger", in a famous scene, Bond is bound to a table and threatened to be cut in half by a powerful laser that Goldfinger later uses to ...
- 121
2
votes
0
answers
94
views
What are the favorite interpretations of quantum mechanics by the recent Nobel laureates in physics?
The new Nobel laureates in physics have been given the prize because of their contributions to quantum mechanics (QM).
Of course, the Nobel prize focusses more on groundbreaking work that has links to ...
- 121
2
votes
0
answers
128
views
Why was the idea of "field" introduced?
I read in my Physics textbook that the notion of Electric fields are useful "when we have to deal with time dependent Electromagnetic phenomenon since no information can travel faster than light&...
- 129
2
votes
0
answers
250
views
Did John von Neumann make any comments about the Many Worlds Interpretation of Hugh Everett?
I was having a discussion with a physicist about Many Worlds Interpretation and he told me that von Neumann like the idea of having multiple worlds in quantum mechanics. When I asked him about more ...
- 297
2
votes
0
answers
75
views
To what extent did d'Alembert want to avoid the newtonian concept of force?
The context of this question:
In everyday life we use push and pull all the time to get things moving, to move ourselves. To ride a bicycle: our feet push the pedals to get moving. To accelerate we ...
- 804
2
votes
0
answers
83
views
How did Cross and Dot signs come in vector multiplication?
We use cross sign in vector multiplication that gives vector result and dot sign that gives scalar result.
But how did the dot sign come in scalar product and the cross sign in vector product? It ...
2
votes
0
answers
70
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 ...
- 703
2
votes
0
answers
174
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 ...
- 317
2
votes
0
answers
65
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 ...
- 121
2
votes
0
answers
587
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 ...
- 3,897
2
votes
0
answers
99
views
Was Becquerel's discovery of radioactivity inspired by his father?
Becquerel was awarded the Nobel prize for his discovery of radioactivity. He was researching phosphoresence and decided one day to place the stuff he used in a drawer to keep it out of the sun. He put ...
2
votes
0
answers
51
views
How did Mach's view on spacetime differ from Einstein's?
We can read in Wikipedia:
Mach's principle, in cosmology, hypothesis that the inertial forces experienced by a body in nonuniform motion are determined by the quantity and distribution of matter in ...
2
votes
0
answers
80
views
How was it discovered that the Magnetic force was orthogonal to the B-field and the velocity of the charged particle?
Forces like the gravitational and the electric force are in the direction of the force field. Why is it that the magnetic force is orthogonal to the velocity of the charge and the magnetic field? Was ...
2
votes
0
answers
53
views
Did Newton discuss and/or use the principle of moments?
This question comes from a point of view of a student in current times. The general curriculum for a physics student presents that a static analysis of a simple system requires that the forces in each ...
- 121
2
votes
0
answers
37
views
Who invented the quadrupole lens for charged particles?
I am wondering who actually invented the (magnetic) quadrupole lens or who used it for the first time. I have found some papers from the 50s and 60s about more complicated systems based on Quadrupoles,...
- 21
2
votes
0
answers
49
views
How close were the slits in Young's experiment? [duplicate]
How close were the slits in the Young's double slit experiment in 1804 (the second one) and how were they realized?
This is not a duplicate of this question: I am not asking about how the experiemnts ...
- 273
2
votes
0
answers
111
views
What prompted Bose's move to Dhaka University in 1921?
Satyendra Nath Bose who discovered boson statistics and is credited by Einstein for also discovering the Bose-Einstein condensate was born in Calcutta, was educated there at Presidency College and ...
- 3,708
2
votes
0
answers
110
views
Einstein's handwritten manuscript on General Relativity
The book "The Road to Relativity" by Gutfreund and Renn annotates Einstein's original handwritten manuscript from 1916 - "The Foundation of the General Theory of Relativity." I can ...
- 21