All Questions

Filter by
Sorted by
Tagged with
21 votes
3 answers
1k views

What happened to analog computers?

When was the last analog computer developed? What about one that is still in use (as in computation or experiment)? Were there major improvement done from the day digital computers became so popular?
user234487's user avatar
17 votes
0 answers
832 views

Did Kontsevich start a lecture with "one I will not define, the other nobody knows how to define, and we will be proving that they are equivalent"?

The story was circulating in early 2000s, so presumably it happened in 1990s. Kontsevich, it goes, opened a lecture course on mirror symmetry with:"This course is about two categories. One I will not ...
Conifold's user avatar
  • 77.8k
5 votes
1 answer
520 views

Origin of "dust" in cosmology?

In cosmology, "dust" refers to a pressureless perfect fluid, which essentially means a continuum of nonrelativistic material particles, such as galaxies. This is a picturesque and unusual piece of ...
user avatar
6 votes
2 answers
442 views

On the development of Newtonian Mechanics

Having borrowed from the library an English translation of Newton's Principia (Motte's), I read the begining sections, Part 1 and the Systems of the world, and noticed that Newton did physics ...
Cicero's user avatar
  • 561
7 votes
1 answer
333 views

Calculation of Gauss leading to 18:7 resonance between orbits of Jupiter and Pallas

After Gauss helped relocate Ceres, he studied the orbit of the asteroid Pallas and discovered (1812) that Jupiter and Pallas have an orbital resonance that is nearly equal to 18:7. For instance, using ...
KCd's user avatar
  • 5,689
5 votes
1 answer
291 views

Non-standard model of arithmetic and Gödel's theorem

I've read Skolem's paper on his non-standard models of the arithmetic ("Über die Nicht-charakterisierbarkeit der Zahlenreihe mittels endlich oder abzählbar unendlich vieler Aussagen mit ...
David's user avatar
  • 53
6 votes
2 answers
972 views

Was Galileo a plagiarizer?

Was Galileo a plagiarizer? If we where to apply to the works of Galileo the general standards of plagiarism that we conform to today at our local institutions, would he be considered a plagiarizer? ...
Neil Meyer's user avatar
5 votes
1 answer
897 views

Were there alternative names for electron orbitals?

Electrons orbits are referred to as s, p, d, and f, then alphabetically. These stand for sharp, principal, diffuse and fundamental respectively (or maybe the German translations). Was any other ...
VicAche's user avatar
  • 1,896
33 votes
3 answers
4k views

Why did the ancient Greeks originally become interested in conic sections?

How much is known, or can be conjectured, about why the Greeks originally became interested in the somewhat arbitrary construction of intersecting a plane with a cone? The folklore that I've heard is ...
Jack M's user avatar
  • 3,149
27 votes
2 answers
2k views

What attracted Einstein to the anomalous precession of Mercury?

The story is usually told starting with Einstein's 1915 paper Explanation of the Perihelion Motion of Mercury from General Relativity Theory, or at least its drafts from 1913-14. It was the first ...
Conifold's user avatar
  • 77.8k
5 votes
0 answers
521 views

Why is ZFC used more widely than NBG?

In studying the solutions proposed for Russell's Paradox on naive set theory (mainly the corresponding entry in the Stanford Encyclopedia of Philosophy) I came across the following considerations: von ...
Luc M's user avatar
  • 151
5 votes
2 answers
306 views

Mathematical interpretation of Aristotelian mechanics

I am looking for books which include a mathematical interpretation of Aristotle's hypotheses about mechanics. I heard that there are a few books which interpret his mechanical ideas mathematically, ...
jack's user avatar
  • 133
3 votes
1 answer
301 views

Planets/stars as more than points of light

Who was/were first one(s) to recognize that what we see in the night sky are not just points of lights but full blown lands(in case of moon and some planets) and so on? I am guessing it would not have ...
AHK's user avatar
  • 33
1 vote
1 answer
1k 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 ...
Gonenc's user avatar
  • 785
5 votes
1 answer
2k views

Why does logical-AND take operator precedence (evaluated first) over logical-OR?

Does logical-AND have precedence over logical-OR because of a reason or was it an arbitrary choice made sometime in the distant past? (Perhaps it could have been the other way around: OR-terms ...
Pete Alvin's user avatar
7 votes
1 answer
206 views

Did classical physicists feel ill-at-ease about point charges?

The point charge concept is clearly a very useful mathematical fiction, but it is also problematic from the point of view of "physical intuition". Even a layperson would feel that an explanation is ...
David Holden's user avatar
44 votes
5 answers
8k views

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 ...
Gonenc's user avatar
  • 785
11 votes
1 answer
567 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 ...
user avatar
12 votes
3 answers
831 views

Is it true that Euler did not prove the sum of the Basel series $\sum_{n=1}^{\infty}\frac{1}{n^2}=\frac{\pi^2}{6}$?

I've heard that Euler actually never managed to prove $$\sum_{n=1}^{\infty}\frac{1}{n^2}=\frac{\pi^2}{6}$$ If this is true, then where does the common misconception come from?
albo's user avatar
  • 965
9 votes
2 answers
2k views

When was it first realized that sound travels with finite speed?

From what date can we trace the knowledge (or the hypothesis) that sound has a finite speed of transmission through air? Thunder/lightning is the most striking clue, but echoes would be the readiest ...
David Holden's user avatar
12 votes
2 answers
13k views

How did ancient Greeks explain moon phases without reflection of sunlight?

Did the ancient Greeks understand that the moon shines by reflection of sunlight, and that this was the explanation of its phases? Did this allow them to conclude that the moon was a sphere? From what ...
user avatar
10 votes
1 answer
534 views

Cavendish Laboratories Photo, 1939

So this photo of the Cavendish Laboratory is from 1939, and I was wondering if anyone knew any more about who was in the photo. (Click to enlarge) From notes I've been given, I believe the front row ...
Savara's user avatar
  • 281
9 votes
1 answer
1k views

What is the origin of the cut and weigh method of integration, is it Galileo's?

I recently heard a story of a clever method of approximating an integral which, instead of using numerical techniques, relied on physically drawing out the graph of a function, cutting it out, and ...
Peter Woolfitt's user avatar
21 votes
1 answer
4k views

Why is the radical symbol $\sqrt{}$ called "radical"?

This question arose in a conversation with a teacher who was introducing square roots to her students. I know from the website Earliest Uses of Symbols of Operation that the symbol $\sqrt{}$ has its ...
Joseph O'Rourke's user avatar
19 votes
2 answers
8k views

What was different about Planck's quantization of light compared to Einstein's?

In describing black body radiation Planck assumed that the energy that can be absorbed or emitted by charges is quantized, i.e., they can only absorb or emit certain quantities of energy. But it was ...
Quantum spaghettification's user avatar
8 votes
1 answer
2k views

Where does Markov operator come from?

I found this definition of "Markov operator" in the book Chaos, Fractals, and Noise by Lasota and Mackey. Denote by $L^1(\mu)$ the space of Lebesgue integrable functions according to the measure $\mu$...
Adam's user avatar
  • 387
10 votes
2 answers
10k views

Why was delta ($\Delta$) chosen to represent change of a quantity?

In many fields, it's common for $\Delta$ (the Greek letter delta) to represent a change or difference. Math uses it, physics uses it, engineering uses it, etc. Why was $\Delta$ chosen for this? I ...
Joe's user avatar
  • 687
4 votes
1 answer
450 views

Why did Kronecker develop the "adjoining a root" construction?

Kronecker is generally credited with the formalization of "adjoining a root to $f(x)=0$". Nowadays it is interpreted as the quotient $K[x]/(f)$, where $K$ is some appropriate algebraic structure in a ...
Jack M's user avatar
  • 3,149
8 votes
2 answers
431 views

First papers on holomorphic functions

Briot and/or Cauchy are often said to have written the first papers on holomorphic functions, explicitly discussing them as such and their special properties. Which papers are these? When and where ...
Gottfried William's user avatar
4 votes
3 answers
7k 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 ...
Mozibur Ullah's user avatar
15 votes
1 answer
643 views

When did we first begin to suspect that the Earth had an Iron Catastrophe?

I've searched, and found some interesting articles on the subject such as the Wikipedia article, which is a nice summary. But most of the references in these articles are to other popular culture ...
ouflak's user avatar
  • 255
3 votes
1 answer
1k views

How was geometry historically used to solve polynomial equations?

I'm researching historical use of geometry to find solutions to polynomial equations. I'd like to ask for those familiar with this topic, could you describe the use of geometry by early mathematicians ...
user975's user avatar
  • 143
4 votes
1 answer
200 views

Why did the "old quantum theory" start off considering circular electron orbits?

It seems that both Bohr and Rutherford assumed circular orbits of electrons around the atom. But why did they do so, instead of assuming e.g. elliptical orbits?
Quantum spaghettification's user avatar
29 votes
3 answers
4k views

Who introduced random variables into probability?

I used to think that the answer is Kolmogorov. So the Shafer-Vovk's review of Kolmogorov's famous 1933 axiomatization of probability surprised me a bit:"Today, what Frechet and his contemporaries knew ...
Conifold's user avatar
  • 77.8k
4 votes
3 answers
5k 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^{-...
HDE 226868's user avatar
  • 8,513
1 vote
4 answers
45k views

What is the importance of SI units in Physics?

Every quantity has some SI units like distance, time, speed etc. Why do we prefer SI units for these quantities?
Shubham Prateek's user avatar
6 votes
1 answer
221 views

Since when do humans know about electric charge?

We know that the electron was discovered in 1897 by J.J. Thomson. So was the knowledge about charge, current, electricity and all those terms related to it which we study today discovered after it, or ...
Shubham Prateek's user avatar
9 votes
1 answer
333 views

Have the results from Computational Physics disprove any physics theory?

We are familiar with the instances when experimental results disproved physics theories, such as the Michelson-Morley experiment. What about computational physics results? To date, is there any ...
Graviton's user avatar
  • 193
15 votes
2 answers
695 views

Historical Survey of Statistical Mechanics

Statistical mechanics is a subject with a particularly rich history. I think of the early debates of Boltzmann and Loschmidt, the rather confusing differences between the approaches of Gibbs and ...
tom's user avatar
  • 251
11 votes
1 answer
973 views

Is anything known about part II of John McCarthy's Recursive Functions of Symbolic Expressions and Their Computation by Machine Part II?

I know that Part I was published while John McCarthy was working at MIT in 1960, in which he describes the LISP language, which he had invented 2 years prior, and is today considered one of the most ...
PandaConda's user avatar
6 votes
4 answers
5k views

What is the first historical reference to the binary search algorithm?

Most of you know what I mean, but I will define it broadly: the binary search algorithm consists in searching iteratively for an element within an ordered set, by asking yes/no questions that will ...
Eynar Oxartum's user avatar
7 votes
1 answer
322 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. ...
Danu's user avatar
  • 3,891
6 votes
6 answers
2k views

Has a digit ever been used to represent the number "10"?

Ten is special to humans, as there are 10 fingers on two hands, and fingers are still the basic counting medium for people. So, was there any digit representing the number "10" in a positional system ...
Barun's user avatar
  • 209
5 votes
1 answer
1k views

Modern usage of alchemical symbols

As far as I know, not many (if any) alchemical symbols have survived in modern nomenclature of science, either in chemistry or any other. I think $\LaTeX$ doesn't even support most of them! I know ...
hjhjhj57's user avatar
  • 1,142
-1 votes
1 answer
210 views

Five perfect solids

Has anyone ever considered the connection between the five perfect solids and the three most important music intervals of 2, 1.5, 1.25 and their two counterparts, 1.33333 and 1.6? The tetrahedron ...
John Shanahan's user avatar
7 votes
1 answer
630 views

Which German scientists had their Nobel Prizes seized during World War II?

George de Hevesy famously dissolved the Nobel Prizes of Max von Laue and James Franck during the German invasion of Denmark. The Nazis had prohibited any German scientist from receiving or keeping a ...
HDE 226868's user avatar
  • 8,513
5 votes
1 answer
1k views

Who invented the swan-necked flask?

In his experiments to disprove the theory of spontaneous generation, Louis Pasteur used a swan-necked flask. One source implies that Pasteur invented it himself, but I haven't been able to find ...
HDE 226868's user avatar
  • 8,513
5 votes
1 answer
544 views

Where did the term "tauon" come from?

The tau particle (so named because it was the third charged lepton, behind the electron and muon) was discovered in the 1970s by Martin Perl and colleagues. In one of the SLAC papers, Perl refers to ...
HDE 226868's user avatar
  • 8,513
8 votes
2 answers
951 views

Who discovered the duality between platonic solids?

As it is well known, every platonic solid has a dual (obtained by interchanging vertices and faces), which also happens to be a platonic solid. I would like to know who was the first person to ...
hjhjhj57's user avatar
  • 1,142
7 votes
1 answer
3k views

How did the term "Michel electron" come about?

The Michel electron is what we call the electron produced from muon decay, and it's named after Louis Michel. I mention this in a paper I'm writing, and I was told that I need to cite it. I can't find ...
Luka's user avatar
  • 71

15 30 50 per page
1
84 85
86
87 88
94