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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2answers
61 views

Was Planck's Constant a huge leap conceptually?

It must have been observed, for example, that there was no element lighter than hydrogen or that there were not different-charged electrons (I believe the electron was discovered prior to Planck's ...
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What are the earliest inventions to store and release energy (e.g. fly wheels)?

I am interested in very early inventions that allowed energy to be stored and released after a delay even it's just a short time. With "invention" I mean a novelty that is the result of ...
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Experimenters regretting throwing away data?

Modern experiments, especially in fields like particle physics, often collect far more data than they can process and save. Similarly, I can imagine that historical experimenters were limited by how ...
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1answer
41 views

Books about the development/history of gravitational theory

I am looking for a book about the history of gravitational theory. It should obviously include discussions of Newton, Einstein, and their theories, and hopefully it would include the work of other ...
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72 views

Who is considered to be an inventor of integrated circuit?

According to Wikipedia and also wide knowledge, Jack Kilby who was working at Texas Instruments is considered to be an inventor of an integrated circuit. It is also often said that Robert Noyce (at ...
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How did Faraday determine the Faraday's constant?

Here is the reference. I'm wondering how he experimentally proceeded to derive the fact the if we pass 96485 Coulombs through a solution, then 1 gram equivalent of substance is electrolyzed.
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Historical proofs of the series expression for the Bessel function of the first kind

Introduction The Bessel function of the first kind $J_n(x)$ ($n \in \mathbb{Z},\ x \in \mathbb{R}$) appeared early among other topics, in Celestial Mechanics, in the series expression of the true ...
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Has someone ever proposed a “many worlds/histories” model where all possible boundary conditions are considered? [closed]

The Hawking-Hartle no boundary condition is a well known model that tries to explain how did the universe begin. The authors considered a "many worlds/histories" model considering a sum over ...
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What is the origin in the discrepancy between engineers' and physicists' notation of waves?

my question is very simple. Physicists use this notation in order to write a (for example) plane wave: $$ \xi(z) = \xi^+ \mathrm{e}^{+\mathrm{i}kz} + \xi^- \mathrm{e}^{-\mathrm{i}kz}, $$ where $\xi^+$ ...
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First paper in derived speeds after collision in relativistic dynamics

In the one dimensional relativistic collision, do you know which is the first paper in which the final speeds in terms of initial rates and rest masses are derived? I found the derivation on Wikipedia ...
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How did physicists deal with the variance of electromagnetism before special relativity?

I am trying to write a paper on how Einstein's special relativity (SR) essentially saved electromagnetism for high school and am confused on how the following two problems were solved. How did ...
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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 ...
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Writing Mathematical Symbols in 20th century

As I was reading some papers written by Schrödinger and Heisenberg back in 1920s, I noticed that the symbols they use such as the integral or summation sign or calligraphic letters are as if printed ...
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1answer
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Where does “the grating equation” come from? Does it have a another name?

What we often refer to as Snell's law: $$n_1 \sin(\theta_1) - n_2 \sin(\theta_2) = 0$$ has quite a bit of history behind it. It can be demonstrated in several ways, one of which is by asserting that ...
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1answer
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Gravity of Plato

What is the description of the gravitational interaction in the philosophy of Plato? Are there some drastic differences from Aristotle's physics?
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1answer
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The unit Ångström

The website http://unitsofmeasure.org/ucum.html tells us whether every unit is metric or not. Metric units can be multiplied by a power of 10 and can be combined with a prefix. One ångström is defined ...
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Gravity before Aristotle

In this wiki article, the history of gravity starts with Aristotle. However, what were the ideas about Earth's gravity and motion of planets before Aristotle?
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Why did no one else, except Einstein, work on developing General Relativity between 1905-1915?

Einstein dedicated his time between 1905-1915 to develop general relativity (GR). It seems strange to me that no other physicists attempted to tackle this problem in this ten-year period. After all, ...
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1answer
137 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? ...
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1answer
136 views

Names of the electromagnetic units in SI

The unit of charge is the Coulomb, named after Charles Augustin de Coulomb. This makes sense because Coulomb's law talks about the force between two charges. But I have seen that the SI unit of ...
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Do we know how Feynmans religious views changed throughout his life?

According to Feynman, there was a quota for Jews at American Universities and when he was accepted on a graduate programme - I think at Princeton - they were told "he's Jewish but he doesn't act ...
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Did the knowledge of Wootz steel actually become 'lost'?

Wootz steel was manufactured in Southern India around two millennia ago. With some people saying as far back as 500 BCE, however, the actual physical evidence of such a steel is by 200 AD. The ...
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2answers
178 views

Portrait of Stephen Butterworth

Does anybody know of a portrait of Stephen Butterworth (1885 - 1958), a British physicist?
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1answer
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How were wavelengths in the electromagnetic spectrum first found?

We now all “know” that visible light has a wavelength between about 380 nanometres and 700 nanometres, and that shorter wavelength are the domain of UV, X-rays, and gamma rays; and longer wavelengths ...
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1answer
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When were white holes theorised?

It seems to me that once black holes were theorised then the obvious singularity at its centre - though only ratified after Hawking and Penrose's singularity theorems - one would have to ask where the ...
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2answers
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How did the current physics curriculum came to be?

By far, looking at several curriculums of High School/First-Year Undergraduate physics. The curriculum always starts with Mechanics, moves into Electricity/Electromagnetism and ends with Modern ...
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Why do physicists call their Hilbert space of states simply the Hilbert space?

In mathematics it's well known that a Hilbert space is a simply a descriptive terminology. It doesn't say, what is ontologically under consideration. One can have Hilbert spaces of a great many things,...
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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 ...
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Why is magnetic flux density named after Nikola Tesla?

I have my respect for Mr Tesla, but it seems weird that "he" was chosen to be the units of magnetic flux density. I mean, he didn't contribute much to magnetic fields theory, nor did he work ...
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Did C.S Peirce make any noteworthy contributions to physics or chemistry?

According to this article Peirce was the first to experimentally tie a unit, the meter, to an absolute standard, the wavelength of a spectral line Did C.S Peirce make any other noteworthy ...
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1answer
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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, ...
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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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2answers
82 views

The reason behind defining the direction of angular velocity towards the axis of rotation?

This is one of those questions which has confused a lot of students like me and I know similar questions have been asked on Physics Stack exchange but I literally want to know what was the reason ...
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Where did Ptolemy compare the Earth to the distance of fixed stars?

I read the following in C. S. Lewis, Miracles (page 77-8) The immensity of the universe is not a recent discovery. More than seventeen hundred years ago Ptolemy taught that in relation to the ...
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Origin of the Fourier transform (1878)

I located Joseph Fourier's book, Analytical Theory of Heat (1878), but at first glance it looks like it is all about heat. What did Fourier call the Fourier transform? When did he first use it?
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275 views

What exactly was the Rutherford model of the atom?

I was recently doing research on the "Rutherford model" of the atom. I found that there seem to be three different accounts of Ernest Rutherford's theory circulating online: Electrons move ...
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53 views

When were the SUVAT equations derived for the first time?

It's one of the first things learned in Physics. However, what's the history behind deriving the SUVAT equations? And, there were other equivalent equations used before SUVAT came into the curriculum?
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3answers
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What are some historical examples in physics of heuristic proofs of mathematical results?

In the proceedings of the XIth International Congress of Mathematical Physics Edward Witten wrote (p. 704) [$\dots$] when a mathematical result is really relevant to a physics problem it often ...
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1answer
75 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 ...
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2answers
76 views

How did Galileo derive the law for a falling body without calculus?

I am asking how did Galileo Galilei derive the equation for height as a function of time, which we now write as $y=\frac{1}{2}gt^2$. We now know that the equation is the solution of Newton's second ...
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1answer
55 views

Have units in physics any link with the origins of type theory in logic?

It is well known that the theory of types, first introduced by Bertrand Russell in 1903 and developed with Whitehead in their Principia Mathematica (1910), was a way to deal with paradoxes in set ...
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Is it true that Newton used the gedankenexperiment of a cannonball revolving around the earth to find the inverse square law of gravity?

I have often heared that Newton compared the centripetal acceleration of an (imaginary) cannonball revolving around the earth just above the surface with the centripetal acceleration of the moon and ...
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1answer
110 views

Did physicists correct an error of mathematicians in counting twisted cubics in the quintic?

One problem in enumerative geometry consists in counting the number of rational curves of degree $d$ in the plane going through $n$ general points. If $n = 3d-1$, this number, denoted $N_d$, is finite ...
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1answer
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Why did Galileo express himself in terms of ratios when describing laws of accelerated motion?

I opened the same question on Physics Stack Exchange, but it seems more suited for this site. I've been reading about Galileo's experiment with inclined planes, and he ends up saying something along ...
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Who first defined pressure?

Before learning any topic, I always find the reason of "Why definitions are created for that particular topic?" In fluid statistics, I encountered a term called "pressure". But I ...
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1answer
75 views

In which article did the physicist Sheldon Glashow introduce his electroweak theory?

In which article did Glashow introduce (1961?) a unified description of the electromagnetic and weak interactions, i.e., the electroweak interaction that earned him the Nobel prize in physics?
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300 views

English translation of Heisenberg's papers

Strangely, many of Heisenberg's very important scientific papers are not translated into English. For example, this one seems not to have been translated. Where can I get the translated ones?
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813 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 ...
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Quotation reference: “functions which can be evaluated under 1 sec are as good as analytically available”

I have a vague memory of a (possibly-apocryphal) quote by a physicist (I remember it as being Giorgio Parisi, which could be wrong), saying something to the effect of "any function which can be ...
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History behind the heat equation

Who was the first mathematician/physicist to derive the heat equation $u_t=\Delta u$ and when? Was it already known to explain most diffusion phenomena? How much time passed between the first ...

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