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Questions tagged [theoretical-physics]

For questions regarding theories in the discipline of physics. Do not use the physics tag on a post if you use this tag in the post.

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182 views

Did amateurs ever produce important proofs or similar?

Background Mathematics and some areas of physics and computer science have the peculiar appeal that some problems and results are easy to understand and it is conceivable that somebody armed with ...
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1answer
146 views

When, and by whom was the Schwarzschild metric first taken to be valid for all radii greater than zero?

The metric was originally defined to be valid only from the surface of a black hole outward but somewhere along the line it was extended inward to include the region under the event horizon. This ...
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1answer
124 views

History of group theory character tables (as used in physics and chemistry)

Does anyone know who started using the symbols A, B, E, T (First column, left) for showing irreducible representations of symmetry groups? In older maths books I see capital gamma. Herein A= totally ...
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1answer
146 views

Who did say that anyone who discover a new particle should be fined instead of receiving a prize?

I am almost sure I read once that a famous physicist said that anyone who discover a new particle should be fined instead of receiving a prize. The context was that at the time there was more and more ...
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1answer
98 views

Why did Noether's theorem take so long to show up?

Obviously like they say hindsight is 20/20, but it seems to me that all the ingredients for Noether's theorem were in place more than a hundred years before its publication, and to be honest it is not ...
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2answers
120 views

Einstein really didn't “accept” quantum mechanics? [duplicate]

It is sometimes said that Einstein didn't accept quantum mechanics. Some stronger claims are that he viewed it as wrong altogether, considering it not a viable description of nature. Well, I want to ...
3
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1answer
114 views

A Peculiar Quote from an Engineer

The best result of mathematics is to be able to do without it. The above is a quote by Oliver Heaviside, an electrical engineer and mathematician. What does the quote really mean?
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2answers
275 views

When did the use of complex numbers become widespread in physics?

Complex number are extremely useful in every branch of physics dealing with ondulatory phenomena. In electromagnetism, for example, they allow to write the solution of Maxwell's equations in a form ...
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0answers
38 views

How much influence did the work of Boltzmann have on that of Gibbs, and vice versa?

Gibbs and Boltzmann were active in the same years (1860s-1900s). However, I often hear that their formulations of statistical physics were developed independently, and that (at least for a long time) ...
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1answer
157 views

Interpretation of $W$ in Boltzmann's entropy formula

Background In the famous Boltzmann's entropy formula, carved in the physicist's tombstone, a mysterious quantity $W$ appears (a): $$S=k_B \log W\label{1}\tag{1}$$ We often hear that $W$ represents "...
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1answer
169 views

Who originally derived the general force law equation of force between current elements?

Wikipedia credits this to Maxwell. This derivation can be found in Maxwell's Treatise on Electricity and Magnetism vol. 2, part 4, ch. 2 (§§502-527). I went through the derivation and found two self ...
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1answer
95 views

Who did enunciate each postulate of modern Quantum Mechanics

Nonrelativistic Quantum Mechanics (QM) relies in a number of postulates and although some authors may disagree about the exact set, there are a few which are quite indisputable: States are ...
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2answers
164 views

When Was Kaluza-Klein Theory Appreciated?

As far as I understand the Kaluza-Klein theory, despite its unprecedentedly profound and beautiful character, had a modest following in its early days. I guess two of the many reasons might be the ...
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1answer
116 views

Who first proposed the “colour” charge?

Does anybody know a paper or sorts in which the term "colour" charge in QCD was introduced first? Or any other source in which this label was proposed?
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1answer
43 views

History of Magnetism before the Hubbard model

I'm interested in models used before the Hubbard model (free electron model, band model, etc, both itinerant and localized models). What were their strengths and weaknesses? Which model is currently ...
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1answer
167 views

Why was the question of the nature of light limited to the wave theory or the particle one ?

The question is in the title. I'm obviously refering to the 17/18 th century somewhere around this era.
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1answer
110 views

History of the fock space based quantization of fields

In almost all Quantum Field Theories textbooks the same approach to quantization is presented as the first example: one considers the scalar real Klein-Gordon field $\phi$ and just write it as $$\phi(...
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1answer
175 views

How Einstein got the first idea for special relativity?

I am reading Big Bang by Simon Singh. Here is the short story (as I understood it): Einstein gets a contradiction by assuming that 1- The speed of light $c$ is constant with respect the ether. 2- ...
4
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1answer
162 views

Why is the action from the principle of least action traditionally denoted $S$?

In theoretical physics, a Hamiltonian is traditionally denoted by some variant of $H$, a Lagrangian is some variant of $L$, but why is an action always some variant of S (as opposed to, say, $A$)? ...
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0answers
70 views

What was Einstein's reasoning to conclude particles follows geodesics through spacetime?

When formulating General Relatvity Einstein proposed that freely falling particles, that is those subject to no forces other than gravity, follows geodesics through spacetime. In other words, those ...
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0answers
71 views

Who first noticed violation of aufbau principle of elements like Cr, Cu, Pd, Au, and how?

It is often referred to as 'anomalous electron configurations' or 'unusual order of filling of orbitals' of a few elements e.g. Cr, Cu, Nb, Mo, Ru, Rh, Pd, Au etc.
4
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1answer
154 views

Einstein already used the idea of time orientation when formulating General Relativity?

The theory of General Relativity as usually presented currently defines the relativistic spacetime as a tuple $(M,g,\nabla, T)$ where $(M,g)$ is a four dimensional smooth lorentzian manifold, $\nabla$ ...
4
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1answer
161 views

What was Liouville's contribution to Liouville's theorem?

Liouville's theorem asserts that the volume of phase space is incompressible. This was first shown by Gibbs 1903 but his name is mostly forgotten. The Wikipedia article says It is referred to as ...
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1answer
380 views

How was the spontaneous symmetry breaking introduced and how did it lead to the Higgs mechanism?

I'm looking for the way things were connected. It seems me to that it was like this: Spontaneous symmetry breakdown was detected in condensed matter physics. (I'm not sure of facts here) Later it ...
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2answers
248 views

What did it historically mean in physics for something to “exist”?

What is the history of influential definitions of objective existence --- This Is Real, It Exists --- in physics? Where did they appear in the literature and in what context were they put forward? ...
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1answer
951 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 ...
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108 views

Was Einstein original formula E =1/2 m c^2?

I read somewhere that, but unfortunately I cannot retrace where, can you help me find a reliable source? Actually, they said a sad story, hardly believable: They stated that Einstein had circulated a ...
4
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1answer
224 views

Has correlation led to major discoveries?

We like to repeat that correlation does not imply casuation. My gut feeling is however that (source: xkcd): Correlation doesn't imply causation, but it does waggle its eyebrows suggestively and ...
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0answers
47 views

Why are Bose-Einstein Condensates (BECs) named after Bose and Einstein?

Why are Bose-Einstein Condensates (BECs) named after Bose and Einstein? What did Einstein contribute to BECs?
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0answers
851 views

Why Doesn't Einstein Get More Credit for Being the Father of Quantum Mechanics?

I'm not simply referring to the notion that Einstein treated the discrete emission and transference of energy (and matter) as "real" physical phenomena, but rather his major continuous role in the ...
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2answers
208 views

How did Albert Einstein predict the existence of gravitational waves?

From Darkest matter: gravitational waves 2016-06-19 | Espresso But black-hole pairs orbiting one another emit something else: gravitational waves. These ripples spread outward like sound waves, ...
6
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1answer
425 views

Max Planck's reaction to Einstein's 1905 STR Paper

It is quite well-known that Planck was one of the first people to realize the significance and importance of Einstein's theory of relativity. But I have heard several times that when Einstein sent his ...
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1answer
45 views

Did Maupertuis ask how a particle knows to follow the path of stationary action?

I have read casual statements without reference suggesting that Maupertuis posed a question similar to Feynman's (in this lecture, for instance) as to how a particle "knows" to follow the path of ...
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2answers
202 views

How did Lorentz transformations get their modern definition?

Historically, Special Relativity was motivated by apparent inconsistencies between Maxwell's Electrodynamics and Newtonian Mechanics. In Einstein's well known paper "On the electrodynamics of moving ...
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1answer
233 views

What is the origin of the “virtual particle pair” metaphor for vacuum fluctuations?

In any layman level description of vacuum fluctuations in quantum field theory the fluctuations are described as a pair of virtual particles spontaneously appearing then disappearing within some short ...
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4answers
507 views

Who was the first to say “Shut up and calculate!”?

The best thing I could find on the internet was this apparently forgotten aricle from 12 years ago.
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2answers
241 views

What made Einstein believe (or know) that time was affected by speed and gravity?

How did he come up with this idea before there was any experimental data to prove this?
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3answers
934 views

Why did Einstein develop General Relativity?

I know that ultimately GR was validated by experiment. I'd like to know however, if there was any experimental discrepancy at the time that pointed to a conclusive flaw in Newtonian gravity, and which ...
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2answers
744 views

Did Feynman develop QED based on Stueckelberg's manuscript?

I found some rumors on the internet regarding Stückelbergs manuscript and it's role for the development of QED. In a comment on here somebody writes: Crease and Mann say in their book The Second ...
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1answer
78 views

Who first developed the idea of conservation of information in physics?

I've recently come across the idea of the "conservation of information" in the so called Black Hole Information Paradox. Yet this article claims that: Conservation of information is a term with a ...
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0answers
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Historical interpretation of symmetries required by Principle of Relativity

Einstein's 1905 paper discussed electromagnetism and the laws of mechanics. But did not discuss gravity, and of course did not discuss the strong or weak nuclear forces. Principle of Relativity - (...
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How did Maxwell conclude that $\frac{\partial\bf E}{\partial t}$ was necessary to complete $c^2\nabla \times \bf B= \frac{\bf J}{\epsilon_0}\;?$

As we know $$c^2\text{curl}\;\bf B= \frac{\bf J}{\epsilon_0}$$ is incomplete & in many cases like capacitor give contradictory result against Law of conservation of charge. As Feynman writes; ...
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2answers
707 views

What was the motivation for Minkowski spacetime before special relativity?

If I understand correctly the concept of a Minkowski space/metric was already known before Einstein's paper on special relativity. Was there any physical motivation for studying this type of metric ...
2
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2answers
262 views

Wireless transmission and speed of light in Weber Electrodynamics

The telegraph model of Weber-Gauss, relying on Weber's electrodynamics, modeled instantaneous action at a distance of the electric scalar potential (Coulomb potential) manifesting as propagation of ...
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6answers
573 views

What are some concepts/discoveries in Mathematics and Science that found practical applicition years after they had been formulated/discovered?

I'm looking for examples of ideas/discoveries/concepts in Maths or Science that had no practical application at first and were maybe considered as nothing but a theoritical concept but they turned out ...
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2answers
651 views

Was Dirac really trying to take the square root of the Klein-Gordon operator?

As a student of physics one will, on several occasions, indubitably hear professors or other physicists (here is an example, from Physics.SE's highest-rep user John Rennie) tell the famous story that ...
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3answers
911 views

When and why did the concept of relativistic mass become outdated?

While browsing on Physics Stack Exchange, I discovered numerous posts (these two are examples) which assert that relativistic mass is an outdated concept used in older textbooks. Looking through my ...
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2answers
899 views

How did Newton establish the conservation laws in the Principia?

In the contemporary axiomatic description the conservation laws in mechanics are deduced from Noether's Theorem using the homogeneity and isotropy of space and time. How did Newton, if he did, ...
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3answers
536 views

Why is the Dirac delta “function” often presented as the limit of a Gaussian with a fraction in the exponent?

I often see the Dirac delta function defined as $$\delta(x)=\lim_{a \to 0}\frac{1}{a \sqrt{\pi}}e^{-x^2/a^2}$$ Yet this is clearly equivalent to $$\delta(x)=\lim_{b \to \infty}\frac{b}{\sqrt{\pi}}e^{-...
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1answer
121 views

What is the origin of the term recombination?

During the introductory lecture to a cosmology course I'm currently taking, there was a brief discussion of some of the "highlights" of the Big Bang model. One of these is, of course, recombination. ...