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.

Filter by
Sorted by
Tagged with
5
votes
0answers
70 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: ...
1
vote
0answers
49 views

Dirac and proton-electron annihilation

Wikipedia says: Robert Oppenheimer argued strongly against the proton being the negative-energy electron solution to Dirac's equation. He asserted that if it were, the hydrogen atom would rapidly ...
3
votes
1answer
82 views

What is the explanation of rope's strength in Galileo's Two New Sciences?

I'm reading Galileo's Two New Sciences. But as other Scientific Book it is hard. I am having trouble in First day, where SIMPLICO asks this question(Page 7): "But how can one make a rope one ...
9
votes
1answer
2k views

Why did Einstein oppose quantum uncertainity?

Einstein always believed that everything is certain, and we can calculate everything. That's why he rejected quantum mechanics, due to its factor of uncertainty. But still quantum physics was right. ...
0
votes
0answers
56 views

What did Hans Bethe think of von Neumann's quantum logic?

Nobel laureate Hans Bethe was a friend of mathematician-physicist John von Neumann, and he once said: "I have sometimes wondered whether a brain like von Neumann's does not indicate a species ...
14
votes
1answer
607 views

Hidden agenda of the Galileo trial?

Redondi argued that Galileo's trial on heliocentrism was merely a show trial concealing the real objection against Galileo among the catholic establishment, which was his atomism thought to be at ...
0
votes
0answers
125 views

Does Einstein's original derivation of $E=mc^2$ exist and what is it?

I read an article published by Scientific American stating that Einstein did not prove the equation within the context of Special Relativity but I am skeptical. I was hoping someone could point me in ...
1
vote
1answer
122 views

Did physicist David Bohm ever propose the existence of a multiverse?

Did physicist David Bohm ever propose the existence of any kind of multiverse?
0
votes
1answer
113 views

What is the ancient cosmic canon of proportion and its role in the history of science?

Who had direct inside knowledge of the canon through the alleged secret oral tradition? Some possible examples that have been alluded to include Pythagoras, Plato, Euclid, Copernicus, Galileo, Kepler, ...
5
votes
2answers
104 views

What is the history behind defining temperature as measure of hotness?

I know that when two bodies of different temperature are kept in contact "heat" flows from hotter body to colder. But how did anyone know that it is the "hotness" that flows, one could have said that ...
3
votes
1answer
113 views

Einstein praising Sophus Lie

p. 153 of Raúl M. Falcón Ganfornina and Juan Núñez Valdés, “Mathematical Foundations of Santilli Isotopies,” trans. Alan Aversa, Algebras, Groups, and Geometries 32 (2015): 135–308. quotes (but does ...
3
votes
0answers
180 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 ...
3
votes
1answer
92 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? ...
2
votes
1answer
52 views

When was spin of subatomic particles other than the electron discovered?

The idea of a spin angular momentum was first proposed in a 1925 publication by George Uhlenbeck and Samuel Goudsmit to explain hyperfine splitting in atomic spectra. At what time was it measured ...
0
votes
0answers
64 views

How does the concept of centre of mass came to existence?

I am wondering as how does the concept of centre of mass came into being. Considering the usefulness of the concept how were the physicist able to define such a quantity. I mean was it just trial and ...
7
votes
1answer
749 views

What is the history of electric current and resistance?

Thomas Kuhn writes in The Structure of Scientific Revolutions Part of what the acceptance of Ohm’s Law demanded was a redefinition of both ‘current’ and ‘resistance’; if those terms had continued ...
24
votes
2answers
2k views

Who discovered the covering homomorphism between SU(2) and SO(3)?

Who discovered this? It is quite nontrivial and very important in quantum mechanics.
3
votes
1answer
166 views

What is the origin of the concept of reduced mass?

I am looking for the origin of the concept of reduced mass as used in vibrational spectroscopy e.g. vibration of a diatomic molecule. Most of the texts simply define reduced mass as the sum of the ...
4
votes
0answers
54 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 ...
4
votes
3answers
175 views

Did anyone mention the possibility of antimatter before 1928?

In 1932 positron and annihilation were discovered, but in 1928 Dirac had provided a formula allowing for the positron Did anyone between that date and the discovery of electron ever imagine or ...
9
votes
1answer
313 views

Were there serious attempts to model the photoelectric effect classically?

Today we see the photoelectric effect as one of the simplest pieces of empirical evidence that leads to quantum physics. The historical development of the subject, however, seems to have involved much ...
2
votes
1answer
55 views

What is Leroy Grumman Medal won by theoretical physicist Kenneth G. Wilson?

I happened to find that one of the most important inventors of the renormalization group, Kenneth G. Wilson, won the Leroy Randle Grumman Award Medal in 1986, 4 years after his Nobel prize. Details in ...
7
votes
4answers
243 views

Textbook on the History of General Relativity

I have studied General Relativity from various textbooks already, and the subject fascinated me immensely. I was wandering if there is any textbook that deals with the chronological "steps" that ...
3
votes
1answer
128 views

How did $SU(2)$ came into physics?

It is natural for physicists to consider the group $SO(3)$. Presumably, $SU(2)$ came into physics because of quantum mechanics. How did people realize that when studying rotation of a physical system, ...
2
votes
1answer
77 views

How was (non-instantaneous) electric current first discovered?

How was (non-instantaneous) electric current first discovered and what were some of the main first thoughts on it?
4
votes
0answers
134 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 ...
9
votes
1answer
1k views

Why do many names of technical and scientific subjects end with “ics”?

The names of many technical and scientific subjects, like mathematics, physics, statistics, etc., etc., end with letters "ics". What is meant by this, if anything? Was there any logic behind it or is ...
6
votes
1answer
86 views

When did the use of Sine and Cosine as functions become mainstream?

In the work of early physicists like Newton, everything is explained in terms of cumbersome (in today's standards) geometry. They don't talk about "cosines" of certain angle, but about proportions ...
0
votes
1answer
83 views

Are these Newton's quotes apocryphal?

I have stumbled upon the following alleged Newton's quotes, but I could not find them in any of their works. No great discovery was ever made without a bold guess. No sciences are better ...
5
votes
3answers
543 views

What is the origin of the $\hbar$ symbol?

Equations involving Planck's constant, $h ,$ are often simplified by instead writing them in terms of the reduced Planck's constant, $\hbar \equiv \frac{h}{2 \pi}.$ But where did the symbol for the ...
0
votes
0answers
69 views

Theory criteria from Misner-Thorne-Wheeler

In chapter 39.1 of Gravitation, by Misner, Thorne and Wheeler, it is asserted, quite reasonably, that a theory of gravitation (and, I assume, quite generally) must satisfy the three following criteria ...
5
votes
1answer
422 views

Why are 'speed' and 'velocity' not given the same name?

Position is a vector. Distance/length is a name of its magnitude. Velocity is a vector. Speed is a name of its magnitude. Acceleration is a name of a vector and its magnitude. Force is a name of a ...
1
vote
1answer
344 views

Why was the reduced Planck constant introduced and when?

When was the reduced planck constant $\hbar= h/2\pi$ first introduced and what was the reason behind introducing such a constant? I know that $E=\hbar \omega$ and $p=\hbar k$ and writing again and ...
6
votes
1answer
3k views

Why is Einstein's mass-energy relation usually written as $E=mc^2$, and not $\Delta E=\Delta m c^2$?

Why is Einstein's mass-energy relation usually written as $E=mc^2$, and not $\Delta E=\Delta m c^2$? When you calculate the energy $\Delta E$ released during nuclear fission, you take the difference ...
2
votes
3answers
2k views

When and by whom was the earliest definition of speed given?

Speed is defined to be distance divided by time; when and who by was this definition first put forward? The obvious guess would be Galileo in early modern physics; is this right, and can it be ...
4
votes
0answers
100 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 ...
4
votes
4answers
353 views

Where did the false “equal transit-time” explanation of lift originate from?

It's supposedly a "widely circulated" false claim that wings generate lift because of their asymmetric shape, forcing air above to travel faster so that they meet up on the trailing edge at the same ...
5
votes
1answer
2k views

What are the major flaws of the “caloric” theory of heat?

I was reading about the history of thermodynamics and came across Lavoisier's idea of heat. He proposed that heat was a fluid. I am curious to know what are the major drawbacks of this theory. I know ...
2
votes
0answers
97 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 ...
1
vote
0answers
35 views

Did Werner Heisenberg ever agree or propose the existence of some kind of multiverse?

I was watching a video (https://www.youtube.com/watch?v=muJYTeQlvC4) where the director of a videogame company speaks about one of its most successful games. This game is set in a floating city which ...
0
votes
1answer
77 views

Reference for history of physics with description of mathematical models

I am interested in some reference text, for example, textbook that would describe going from old times (say, Greece) till modern times: 1) definitions of units and measurements 2) describing ...
2
votes
0answers
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 ...
4
votes
1answer
3k views

An English copy of One Hundred Authors Against Einstein?

I've been trying to find the famous article, "One hundred authors against Einstein" (100 Autoren gegen Einstein), of various objections to special relativity, which is quite often referenced, but ...
1
vote
0answers
85 views

What did people mean by the term Force in earlier times?

Initially I used to believe that before Newton gave his Laws of Motion, people thought that Force was something that caused motion. It was Newton who first said that Force is something that causes ...
19
votes
1answer
2k views

How was Einstein led to make a contact with Differential Geometry for his theory of General Relativity?

General Relativity was developed with Differential Geometry as the tool. How was Einstein led to make a contact with Differential Geometry for his theory of General Relativity? Who suggested him to ...
23
votes
7answers
5k views

In ancient times, how did people conclude that the shape of Earth is a sphere?

This is more of a philosophical question, but I want a mathematical explanation. During ancient times, it was well accepted that the surface of Earth was spherical. People first observed this when ...
2
votes
1answer
107 views

What was this experiment tainted by the observer effect?

I once heard a cautionary tale about the dangers of the observer-expectancy effect. It was at least presented as a true example from the history of science, but I'm having trouble identifying the ...
0
votes
3answers
98 views

Does Heliocentrism predate Copernicus?

I have seen this mentioned on the interwebs a few times. people have mentioned that some Greek thinkers and Islamic astronomers came up with heliocentrism before Copernicus and that Copernicus copied ...
3
votes
0answers
306 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 ...
2
votes
0answers
50 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 ...