# 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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### Where did Master equations come from, and why are there so many of them?

The Wikipedia article about the Master equations describes pretty well how many there are and what kind of equations are called "Master equations". Does anyone know where the term originates, why ...
643 views

### Introduction of the Gravitational constant

The constant G in Newton's law $F = G m_1m_2/r^2$ is, as far as I know, absent from Newton's work - who introduced this constant?
410 views

### Who introduced the creation and annihilation operators for the harmonic oscillator?

Or who first solved the harmonic oscillator in the algebraic method?
1k views

### What is the history of the energy concept and its measurement?

Could someone please explain how the concept of energy was originally conceived and how it evolved over time to our current understanding of it? Also how did people come about various ways of ...
689 views

### When and who was the first mathematicians to prove rigorously that $\sqrt[3]{2}$ was impossible number? [closed]

The purpose of the question is to understand why the number $\sqrt[3]{2}$, that was proven rigorously by ancient Greek is an impossible number (even at infinity), by their three famous impossibility ...
161 views

### Mutual induction in electromagnetic wave theory

Frequently when electromagnetic waves are taught, it is said that the change in electric field causes a change in the magnetic field, which then causes a change in the electric field, and so on and so ...
478 views

### When or why & who originated this puzzle, $0.999… = 1$ [duplicate]

The problem is the infinite or endless repeated digits of $9's$ after zero digit and the decimal notation, Despite its apparent simplicity & the huge talk about it every where in mathematics or ...
1k views

### Origin of the word “vector” [closed]

I would like to know the history and the original meaning of the word "vector". Thank you for any hints.
542 views

### Who discovered paramagnetism first?

Ferromagnetism is experienced by everyone. But paramagnetism is not easy to perceive. So, who discovered paramagnetism first? The question is actually, who distinguished paramagnetism with ...
636 views

### Who discovered diamagnetism first?

Ferromagnetism is everyday life. Paramagnetism is not rare. But diamagnetism is rare and weak. So, who first discovered diamagnetism? in which material?
163 views

### 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; ...
315 views

### How did Källén get his name attached to $x^2 + y^2 + z^2 - 2 x y -2 x z- 2 y z$?

For some reason, everybody refers to the function $$\lambda(x,y,z) = x^2 + y^2 + z^2 - 2xy -2xz-2yz$$ as "Källén's triangle function." (see for example https://en.wikipedia.org/wiki/Gunnar_Källén). ...
1k views

### Who gave mathematical expression for torque?

I am trying to understand the conceptual development of the "torque". I saw that Archimedes was the one from whom this idea took birth. I wanted to know from whom the torque got its mathematical form. ...
4k views

### Who said $\pi$ is a constant since it is not even a real number?

EDIT: (130116) I don't mean it is complex or imaginary nor it is negative also, I tried hard to conceive it on the real line number (positive X-axis), by obvious means, a little idea came to me?, "...
119 views

### Who was the first to prove the Boltzman H-theorem for the Landau kinetic equation?

Who has proved Boltzmann's H-theorem (which tells that entropy of a closed system grows as the system approaches thermal equilibrium) for the kinetic equation with Landau collisions operator? One ...
218 views

### Sources of early modern atomic theory of matter?

Modern atomic theory of matter is often attributed to Dalton in 1803, with roots going all the way back to Democritus, but I was wondering about early modern antecedents of Dalton's theory, perhaps in ...
82 views

### Historical milestones in experimental “verification” that light is a electromagnetic phenomenum

This is a follow up question to How did Maxwell conclude that light is an electromagnetic wave? where the arguments of Maxwell were explained why he considered light as an electromagnetic wave. What ...
179 views

### How was difference in water pressure perceived in ancient cultures or the middle ages?

I recently wondered: Even when diving to just 2-3 meters without any modern equipment one can feel the change in pressure. Do we have any evidence how this was perceived and explained back in ancient ...
461 views

### What were the criticisms against the introduction of “vector analysis”?

Frequently, 19th century physicists—e.g., Helmholtz or Maxwell—did not use modern-day vector notation, which Gibbs contributed in large part to. For example, Helmholtz in his famous paper on the ...
713 views

### How did gyromagnetic ratio come up before quantum mechanics, and who introduced it?

I am really curious about who was the first one to define the gyromagnetic ratio $\gamma$ of a body, i.e. the ratio of its magnetic dipole momento to its angular momentum. It is a very important ...
3k views

### How did Maxwell conclude that light is an electromagnetic wave?

This is a copy of a question I just asked at Physics Stack Exchange. From reading the text on the related questions, it seems that Maxwell equated light with the carrier of electromagnetic force just ...
1k 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 ...
249 views

### How did Kepler infer three-dimensional positions from Tycho Brahe's data?

This has bugged me for some time. Tycho Brahe's data on planetary observations, presumably, consisted of the direction in which a planet was observed at a given date and time, but not the distance to ...
86 views

### Did the concept of the Dirac Sea influence the development of semiconductors like the transistor?

Dirac (1928), (http://rspa.royalsocietypublishing.org/content/royprsa/126/801/360.full.pdf) explained the negative-energy solutions of his equations as holes in a sea of electrons. The concept seems ...
41 views

### Original paper for Young's double slit experiments [duplicate]

I'm trying to find the original papers describing Young's double slit experiments including his experimental set-ups and findings. I've tried looking and all I can find is http://www....
2k views

### Original paper for Young's double slit experiments [duplicate]

I'm trying to find the original papers describing Young's double slit experiments including his experimental set-ups and findings. I've tried looking and all I can find is http://www....
208 views

### Who popularized the question “why is the sky blue?”

"Why is the sky blue" is a question that everybody seems to know, and in modern times is associated with children's innate curiosity. If I casually flip through a few of the children's science books I ...
3k views

### Why is there no named unit for momentum but there is one for energy?

Momentum and energy play very similar roles in mechanics, each being changed by the application of force over a interval. For energy the interval is in space and for momentum it is in time. Both have ...
92 views

### Who discovered the Rayleigh-Taylor instability?

Who discovered the Rayleigh-Taylor instability? Was it artist David Alfaro Siquerios? Or was he the first to observe it?
3k views

### Why do Maxwell's equations bear his name?

Maxwell's equations in their modern differential form are: $\nabla \cdot \mathbf{E} = \dfrac {\rho} {\varepsilon_0}$ (Gauss's law for electricity) $\nabla \cdot \mathbf{B} = 0$ (Gauss's law for ...
1k 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 ...
146 views

### What is the earliest mathematical formula describing magnetism?

What is the earliest formal equation of magnetism? The history of discovery of magnetism can trace back to Thales of Miletus. Although many people had discovered, they did not formalize an equation.
11k views

### Why are microwaves called “microwaves”, when they are much longer than a micrometer?

If "millimeter waves" have a wavelength of about 1 mm, one might linguistically expect microwaves to have a wavelength of about three orders of magnitude less, not the same or greater. How did ...
76 views

### When and how was water first detected outside of Earth?

When and how was water (in ice or any other state) first observed outside of Earth? What is the high-level chronology of this discovery, and how did the scientific community first reach reasonable ...
628 views

### How did quantum mechanics operators come into being?

Now I am starting to learn Quantum Mechanics. In the class I am taught about operators, postulates and all other basic stuff. I understand operators to be +, -, /, etc; but quantum mechanical ...
1k views

### What are Archimedes's contributions to the principle of the screw pump?

I read that the famous screw pumps were used before Archimedes (in the hanging gardens of Babylon for example), and that the Archimedean screw is named after him because he "developed a rigorous ...
211 views

### Was Einstein the first person to think of the equivalence of a ball drop in an accelerated elevator and a ball drop on Earth?

Consider the following figure taken from Wikipedia. Was Einstein the first person to think of the equivalence of a ball drop in an elevator with acceleration of $g$ and a ball drop on Earth? To be ...
149 views

### Landau doubting conservation of energy---and what followed

When the original beta decay experiments seemed to suggest that energy was not a conserved quantity, Landau (among others) proposed that energy conservation was a statistical law rather then a ...
511 views

### Nobel Prize work derived from Manhattan Project research?

There are quite a few Nobel Prize winners (e.g. Physics) who worked on the Manhattan project in the development of the atomic bomb. But, did any Nobel Prize result from direct research performed on ...
228 views

### Why did Greek Olympic games take place every fourth year?

I was wondering why Greeks chose to have Olympic games every four years. Now, since we usually every fourth year is a leap one, it makes sense; but the reform of the calendar which stated this is due ...
4k views

### Is Millikan's famous oil drop experiment a fraud?

I read in my mechanics textbook written by Goodstein that Robert Millikan cherry-picked his data in his famous oil drop experiment, and now I'm left wondering about the scientific value of his results....
88 views

### How did each base quantity get its name? [closed]

I've tried searching everywhere, but I can't seem to find anything related to how the quantities got named! Base quantities: Mass Distance Time Temperature Electric current Quantity of a substance ...
56 views

### Were Lagrangian coordinates or Eulerian coordinates used first in continuum mechanics?

In these lecture notes, I read about two different ways of looking at the position of a particle $\mathcal{X}$ in some body $\mathcal{B}$, Lagrangian and Eulerian coordinates. In Lagrangian ...
2k views

### How did Ising pronounce his name? [closed]

The surname of Ernst Ising, of Ising model fame, is often pronounced as EYE-zing by non-German speakers, but as EE-zing by German speakers. It is frequently claimed that EE-zing is the correct ...
667 views

### History of the study of indeterminism in classical mechanics

The classic Norton's dome problem, space invaders and other examples, show that Classical Mechanics, held as the paragon of determinism for ages having inspired Laplace's statements on determinism, is ...
1k views

### Conflict between physics and philosophy

In the old days. stars of physicists like Einstein$^{[1]}$, Poincare, Heisenberg, Pauli, $^{[2]}$ Bohr and so on are quite philosophical mind, and like philosophy. $^{[3]}$ But now, it seems to me a ...
1k views

### Was Thomson's model of Plum Pudding widely accepted as a model of atom?

Was this model widely accepted in the time as a model for the atom? or was it just a model between many alternatives?
142 views

### Looking for a Book Which Discusses the Rigor in Newton's Principia Mathematica

About an year ago, I had seen an article somewhere on the internet which discussed Newton's Principia Mathematica and the rigor (or lack thereof) of the arguments presented. I have forgotten who the ...