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
1
vote
1answer
111 views

Why can Perrin's study of Brownian motion demonstrate the existence of atoms

I really cannot see why the Brownian motion is linked with the being of atoms. Cannot it be explained without atoms? You just need some fluctuations.
3
votes
1answer
340 views

Was Rutherford's atomic model questioned at the time?

Thomson's atomic model is a static model. Rutherfold's model is a dynamic one. This poses an apparent problem, i.e., the electrons orbiting the nucleus will radiate and fall into the nucleus. ...
1
vote
0answers
112 views

Modification of Newtonian Gravity based on Maxwell's Theory

As is well-known, Maxwell's equations were already consistent with Special Theory of Relativity while the Newtonian law of Gravitation wasn't. It can be shown by solving the equations of Maxwell for a ...
1
vote
1answer
58 views

Was the pre-special relativity discussion a hot topic in the late nineteenth and early twentieth century?

We know that low-dimensional materials and topological materials are some of the current hot topics in Physics. Did this happen with the pre-special relativity discussions in the late nineteenth and ...
21
votes
2answers
38k views

Why did Tesla disagree with Einstein?

Both Tesla and Einstein were brilliant scientists. Tesla said the following on the theory of relativity in a 1935 New York Times interview: "The theory, wraps all these errors and fallacies and ...
2
votes
1answer
264 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 ...
1
vote
3answers
322 views

Biographies on 20th Century physicists

I've recently finished reading Helge Kragh's Quantum Generations and am looking forward to something to read next. I am hoping to find biographies or more information about certain physicists such as ...
2
votes
1answer
167 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 ...
8
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. ...
5
votes
1answer
544 views

Why do we write $E=mc^2$ and not $E=c^2 m$?

My question goes from Phys.SE where people advised me to ask my question here. I always learn in maths and physics when something is a constant in an equation we have to put it before which varies. ...
4
votes
1answer
6k views

Old square bracket notation for units

As discussed in this answer https://physics.stackexchange.com/a/77691/667 there are several common conventions for the notation $[q]$ of a physical quantity $q$. However, I often see people to put ...
4
votes
1answer
115 views

who was the first to discover the Hamilton principle of classical physics?

Who, besides Hamilton, was instrumental in discovering at least part of the so-called Hamilton principle? $$\delta \int_{a}^{b}L(q,\dot q ,t )dt$$ where $ L=T-V$, the Lagrangian. What exactly, was ...
1
vote
0answers
104 views

First appearance of the timelike cylinder spacetime

Spacetimes with causality violations go back a bit of a way (at least as far back as Herman Weyl's "Space, Time and Matter" in 1922, followed by the Gödel spacetime in 1949), but one of the simplest ...
15
votes
1answer
675 views

How did the publication feat of Einstein's four 1905 Annus Mirabilis papers get through peer review?

Einstein's early career is well-known for the lack of success he had applying for assistant lecturer positions with universities; he could not get a position, and he ended up working in a Bern patent ...
3
votes
2answers
1k views

Who is the philosopher Feynman cites as saying that existence of science requires the same conditions to produce the same results?

In part 6 of his lecture series "Character of Physical Law", Richard Feynman remarks: A philosopher once said, "It is necessary for the very existence of science that the same conditions always ...
0
votes
1answer
264 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.
1
vote
2answers
111 views

When did the British science take off?

The first few big scientists like Copernicus, Tycho Brahe, Kepler, Galileo are not British. Then comes Newton. And since then it seems that the British start dominating science. What was the social ...
2
votes
2answers
351 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- ...
1
vote
1answer
411 views

What did Millikan expect to find when he tried to disprove the photoelectric effect, but proved it instead?

We know that Millikan ended up proving Einstein's photoelectric equation instead of disproving it. Since he aimed at disproving it, what did he have in mind? In other words, what did he expect to see?
-1
votes
1answer
109 views

How did people describe the frequency of a wave before Hertz? [duplicate]

It is actually quite strange that the unit of frequency was defined so later. How did people like Newton, Lagrange describe the frequency of a harmonic oscillator?
3
votes
0answers
107 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.
11
votes
3answers
3k views

When was it first discovered (or comprehended) that air has weight?

When was it first discovered (or comprehended) that air has weight? Did the ancients know of this, or did they think that air is weightless?
1
vote
1answer
146 views

Why did Einstein get a better hearing in Goettingen than Berlin?

Jeremy Gray in his 2008 book writes matter-of-factly that Albert Einstein "found he got a better hearing from Hilbert and Klein in Goettingen than he did from his colleagues in Berlin" (page 326). ...
1
vote
0answers
93 views

Taking less than a minute to solve a problem within 10% which was stated in less than 10 seconds?

I believe there is a story about a 20th century sciencist (either Neumann or Feynmann I think) who, at some dinner or some sort of gathering, made the following claim to his fellow colleagues: He ...
4
votes
2answers
320 views

Did Kepler arrive at his planetary laws based on Mars's orbit alone?

Kepler apparently arrived at his first two laws based on the Tycho's data for Mars. But Mars has the largest eccentricity except for Mercury, so it is easier to tell the difference between a circle ...
2
votes
1answer
138 views

Old textbooks on statistical mechanics

I am going to teach history of physics next semester. Can anyone name some old textbooks on statistical mechanics? By old, I mean written around 1930 or earlier. I would like to compare the old books ...
1
vote
1answer
229 views

What were the most important discoveries of Galileo in mechanics?

Galileo was a real physicist and mathematician besides being an astronomer. But what were his contributions to mechanics like throw and fall and collision? Did he perhaps already know Newton's first ...
3
votes
2answers
577 views

Who introduced the partition function?

Is it by Gibbs? Or Boltzmann? I do not expect Maxwell. The point is, how was the textbook introduction of partition function today developed.
6
votes
4answers
2k views

Why are canonical coordinates canonical?

Canonical coordinates are coordinates $q_i$ and $p_i$ in phase space that are used in the Hamiltonian formalism. The canonical coordinates satisfy the fundamental Poisson bracket relations: \...
3
votes
0answers
321 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 ...
5
votes
1answer
128 views

Who was the first person to describe turbulence in mathematical terms?

Here I found that: Sixty years later, Russian mathematician Andrey Kolmogorov furthered our mathematical understanding of turbulence when he proposed that energy in a turbulent fluid at length $R$ ...
6
votes
2answers
3k views

How did Newton come up with his formula?

In high school students are taught the formula that describes the universal gravitational force $F=G\frac{m_1 m_2}{r^2}$. However it is not taught how and why Newton came up with it. Does Newton give ...
3
votes
3answers
987 views

“Cycles” to “Hertz”: Why the shift circa 1970?

Before circa 1970, it was more common to say "kilocycles" than "kilohertz" (and analogously for "mega-," "giga-," etc.). What contributed to "Hertz" becoming more common than "cycles"? cf. the Google ...
-1
votes
1answer
52 views

looking for specific book about renaissance physics

I read a book a while ago about the history of physics in the renaissance, which treated it as an alternation between physical-causal descriptions (eg. inertia obtains because air molecules are pushed ...
2
votes
2answers
333 views

What is Galileo's opinion of Kepler's work?

They are contemporaries. Keper lives from 1571 to 1630, and Galileo lives from 1564 to 1642. The former's life span is contained in that of the latter. So, did Galileo hear of Kepler's work and give ...
3
votes
1answer
72 views

Is reference cited by Rene Descarte available?

In 1634 Descarte wrote to Mersenne : let me tell you about an experiment that was published not long ago in Leurechon’s Mathematical Games. It involves a large cannon placed on flat ground, ...
11
votes
1answer
349 views

When did people notice the special shapes of snowflakes, and when did they start to study them?

What was the first written account about snowflake shapes and when did physicists start to study the reasons why the form appears and how snowflakes form in the air? Is there any old book that ...
3
votes
1answer
302 views

How did Kepler make his discovery?

It is often said that he used Tycho's data. But the apparent motion of a planet is chaotic, right? The reason is simply that we are living on and observing from the earth, but not the sun. So, how ...
4
votes
1answer
210 views

Did Einstein ever refer to the coordinate speed/velocity of light?

In modern parlance we talk about two different speeds of light in general relativity. We distinguish between the local speed of light, which is always $c$, and the coordinate speed of light, which can ...
2
votes
1answer
111 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.
6
votes
1answer
287 views

Who discovered the normal mode decomposition of coupled oscillators?

Coupled oscillators can be broken down into a superposition of normal mode oscillations. Who was the first person to solve for this system in this way?
2
votes
2answers
240 views

Poincare Quote Regarding Instability

Poincare wrote (english translation of the french) in 1903: ``A very small cause that escapes our notice determines a considerable effect that we cannot fail to see, and then we say that the effect is ...
16
votes
3answers
1k views

Did light bulb companies commission Planck to study black body radiation?

Background When introducing Planck's switch to looking at black-body radiation, a number of sources -- like MinutePhysics, the Economist, random online encyclopaedias and even here on HSM.SE (plus ...
0
votes
3answers
3k views

Why does Newton claim : “Plato is my friend — Aristotle is my friend — but my greatest friend is truth.”?

Basically, why did Newton write : "Plato is my friend — Aristotle is my friend — but my greatest friend is truth." ? What were the influences of these two on him ?
8
votes
2answers
325 views

Did Bruns establish that the 3 body problem has no non-trivial conservation laws?

I'm reading Colin Pask's book Magnificent Principia and in 16.7.2 he states that the difficulty of the 3 body problem is in part tied to the lack of additional conservation laws at our disposal. In ...
4
votes
1answer
167 views

When was the electronvolt first introduced?

When was the unit "electronvolt" (eV) first introduced, and by whom? The definition of the eV requires the knowledge of the electron charge $e$, so it must have been introduced after 1909, the date ...
6
votes
3answers
684 views

Galileo's Discussion of Uniform Motion

Can someone help me here? the language is archaic. This is (translation of) Galileo If two particles carried at a uniform rate, the ratio of their speeds will be the product of the ratio of the ...
3
votes
0answers
70 views

What is the first effect demonstrating the importance (or existence) of quantum coherence?

As far as I know, in the old quantum theory, a system can only reside in a stationary state. There was no Hilbert space, and no linear superposition. Or, a system cannot be simultaneously in two ...
4
votes
1answer
77 views

Who first wrote down the spin-orbit coupling term in the atom?

Who first wrote down the spin-orbit coupling term in the atom? Was it Dirac himself? The term should be derived from the Dirac equation.
5
votes
2answers
960 views

Why couldn't Huygens explain diffraction using his principle?

Huygens' principle seemed quite complete in this description if applied correctly. I noticed that Fresnel was credited in the Huygens-Fresnel principle, as well. I think it is because he was able to ...

1
4 5
6
7 8
10