The historical development of physics concepts: who did what and when.

learn more… | top users | synonyms (1)

6
votes
0answers
37 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. What techniques did ...
2
votes
1answer
32 views

How did Kepler formulate his second law from data?

It's amazing that Kepler derived his three laws emperically and then Newton rederived them from his own laws of motion. Its conceivable how Kepler derived the first and third laws, but the second law? ...
-1
votes
0answers
32 views

How did Cassini measure the distance from earth to sun?

Cassini measured the distance by measuring the parallax of Mars from Paris and his friend, Richer from Cayenne. Now I need the exact procedure of taking the readings, combining the reading and finally ...
3
votes
0answers
36 views

Why is an Ampere an SI unit? [duplicate]

It has always annoyed me that an Ampere is an SI unit, rather than a Coulomb. Why is this the case? Was current discovered first historically? I believe that the standards were published in the 1960s, ...
2
votes
1answer
116 views

How did Einstein arrive at the right hand side of his general relativity tensor equation?

It seems Einstein postulated the right hand side of his field equations… I see in books that tell the story of how he arrived at what to put on the right hand side of his tensor equations, the physics ...
1
vote
0answers
36 views

Why did Heaviside eliminate the magnetic potential from Maxwell's Equations?

Maxwell's original equations had magnetic potential, but Heaviside eliminated this variable. What was the reason for Heaviside's removal of the magnetic potential?
3
votes
0answers
98 views
+50

What is reduced momentum in “A Dynamical Theory of the Electromagnetic Field” by James Clerk Maxwell?

I was reading Maxwell's paper titled A Dynamical Theory of the Electromagnetic Field. In part 2, section 3 ("Dynamical Illustration of Reduced Momentum"), Maxwell discusses a mechanical illustration ...
0
votes
0answers
46 views

Who first discussed the Lorentz-force w.r.t. special relativity? [migrated]

The fact that a Lorentz-force in a reference frame 1 can become a Coulomb-force in another reference frame 2 has always astonished me, especially because the velocities involved are really small. I ...
-1
votes
2answers
127 views

What's the symbol behind Einstein's head? [closed]

What's the symbol called that's behind and to the right of Einstein's head in this picture? Bonus if you can tell me what the whole formula is!
3
votes
0answers
61 views

When did people start to regard “time” as a physical quantity? [closed]

I was trying to figure out how people came to know about time then I realized that people started keeping track of time to know about sunset and sunrise. But I can't figure out how did time came into ...
3
votes
2answers
99 views

How were the ratios of distances between planets and the Sun first calculated?

I was reading some literature and I found that long before the actual distances between other planets and Earth or distance between Sun and Earth were known, physicists had calculated the ratios ...
2
votes
0answers
73 views

If the field concept was invented by Faraday, then how did Newton interpret the $g$?

This is Newton's law of universal gravitation. $F=G\frac{m_1.m_2}{r^2}$ Gravitational field $g$ is derived from this formula $g=G\frac{m_1}{r^2}$ This is named gravitational "field" strength. If ...
0
votes
0answers
33 views

Did the pioneers of nuclear physics and radioactivity eventually get sick from their experiments? [migrated]

We read about nuclear physics and radioactivity in books and we know how to keep safe from their harmful effects, but the physicists who first discovered them didn't have that luxury. Did the pioneers ...
5
votes
3answers
182 views

What theoretical predictions took the longest to be experimentally confirmed? [closed]

Looking forward to Einstein's general relativity centennial in 2015, I was thinking about how cool it would be if LIGO detects gravitational waves in 1916 (centennial of Einstein's "weak field" paper) ...
2
votes
6answers
566 views

On the foundations of quantum physics

Quantum physics has to be validated by experiments. But experiments are to be interpreted in the context of quantum physics. Isn'it like a snake biting its own tail? For example, using a scanning ...
5
votes
2answers
211 views

How did the operators come about?

This relates a little bit to my previous question (Experimentally, what categorizes a measurement as corresponding to a certain observable?), but it's different in a way and more historical. One of ...
3
votes
1answer
96 views

Einstein's space-time theory [closed]

I'm a high school student who never studied any relativity before, but I'm just wondering what was THE question that Einstein asked himself before going into this field. I knew he has done lots of ...
9
votes
3answers
1k views

How did Rutherford's gold foil disprove the plum pudding model?

What stops one of the two following scenarios from happening, consistent with the plum pudding model? The $\alpha$ particle, attracted by the electrons on the outer shell of the pudding, orbits ...
0
votes
0answers
48 views

debates on “infinity” in contemporary physics?

During the seventeenth century many philosopher-scientists, such as Leibniz, were preoccupied with the philosophy and mathematics of infinity. Famous problem were the "labyrinth of the continuum," ...
3
votes
0answers
89 views

History of QFT after 1973 [closed]

Where I can read about history of development quantum field theory after 1973? I'm interested in historical reviews, like as first chapter of the Weinberg's book.
3
votes
1answer
65 views

Maxwell's Inspiration to think about fields

I was looking at a Wikipedia article which had the following statement Atomists, notably James Clerk Maxwell and Ludwig Boltzmann, applied [...]. In modern literature Maxwell is often thought ...
2
votes
1answer
34 views

How did Planck use the concept of statistical entropy in trying to understand the meaning of his own law?

I was reading Introducing Quantum Theory: A graphic guide (by J.P.McEvoy & Oscar Zarate) and came across Planck's predicament of understanding his very own law that accurately explained the ...
0
votes
0answers
29 views

Everything moves at the speed of light? [duplicate]

Whatever happened to that idea? Presumably it came from a concept known as Zitterbewegung. As wiki says, a theoretical rapid motion of elementary particles, in particular electrons, that obey the ...
0
votes
0answers
21 views

What is the history of the multichannel analyzer?

I'm doing a presentation over multichannel analyzers and one of the topics is "A Brief History of Multichannel Analyzers" and I am having great difficulty finding anything on the subject. I have done ...
2
votes
1answer
44 views

Prerequisites for Ptolemy's Almagest

I hope this is a valid question to ask on this website (since it's astronomy and not e.g. mechanics, I wasn't so sure). What prerequisites are needed for fully understanding Ptolemy's Almagest. Fully ...
5
votes
2answers
127 views

How exactly does applying the Equipartition Theorem to radiation leads to UV catastrophe?

I'm reading a book by George Gamow, "Thirty years that shook Physics" and have trouble understanding his way of describing the UV catastrophe. In a first part he points out that applying the ...
5
votes
0answers
46 views

Where do Newton's laws come from? [duplicate]

I have studied physics for about three years at university but after these years I still don't know how Newton derived his laws. I know that he tried to find the best model to describe the motions ...
29
votes
2answers
3k views

What are Stephen Hawking's main contributions to research-level physics?

Without a doubt, Stephen Hawking is the most famous living scientist; indeed, his public visibility in all of history seems to be rivaled only by Einstein and easily eclipses giants of physics such as ...
1
vote
1answer
313 views

How did Newton establish his famous third law of motion?

For every action,there is equal and opposite reaction . This is the famous Newton's third law of motion. But how did he come to this conclusion? We can prove 2nd law using calculus. But how did Newton ...
2
votes
0answers
46 views

Which scientists have managed to name their laws/terms after themselves? [closed]

It would be pretty vain for someone to name a scientific law, unit, or term after themselves. "Newtons" as the name for the measurement of force, for example, was adopted in 1948, so I don't expect ...
4
votes
1answer
52 views

Why is the specific notation used for term symbols useful?

This has bugged me for a long time. Term symbols describe electronic states of atoms which have well-defined total electronic angular momentum $J$ as well as total spin and orbital angular momenta ...
3
votes
2answers
218 views

What made Einstein think that gravity was caused by the curvature of spacetime?

What observation/thought experiment led him to think this?
3
votes
2answers
294 views

How did Isaac Newton figure out how the law of gravity worked? [duplicate]

There are this and this similar Phys.SE questions, but I didn't find what I'm looking for, nor was the person's question specific enough. How did Newton figure out $$F=GMm/ r^2~?$$ What was his ...
0
votes
1answer
190 views

How did Newton discover the universal law of gravitation?

I am having trouble comprehending how anyone could come up with this formula: $F = \frac{GMm}{d^2}$ Could someone walk me through this?
2
votes
0answers
71 views

Formulas for Haitz's law?

The Nobel Prize in Physics 2014 is for LED. There is a related Haitz's law: ...every decade, the cost per lumen (unit of useful light emitted) falls by a factor of 10, and the amount of light ...
3
votes
2answers
413 views

Who discovered that electromagnetic wave doesn't need a medium?

I have read that physicists in 19 century searching for the aether. They thought that light must have some medium to carry. When did they know that light and other electromagnetic wave doesn't need ...
2
votes
2answers
295 views

How Reynolds number was derived?

I'm studying fluid dynamics and recently the formula $Re=\frac{\rho vd}{\eta}$ was presented to me. I'm curious to know how Reynolds came up with this relations between this different variables. Did ...
0
votes
0answers
42 views

Magnesium Diboride - why was it missed?

In 2001 it was found to superconduct at 39K, which is about twice the record for materials up until the 1980s when the cuprate high temp superconductors were discovered/invented. My question is ...
2
votes
2answers
930 views

Why do we use kilograms instead of newtons to measure weight in everyday life?

What was the reason to use kilograms to measure weight (e.g. body weight, market vegetables etc.) instead of using newtons?
7
votes
1answer
83 views

What experiment disproved single fluid theory of electricity?

I just can't understand how history of electricity goes on. What experiment disproved Benjamin Franklin's fluid theory of electricity?
1
vote
0answers
29 views

Deriving Ampère's Circuital Law from Ampère's Force Law?

Ampère's force $d^2\vec{F_{21}}$ of current element $i_2d\vec{\ell_2}$ on $i_1d\vec{\ell_1}$ is$$d^2\vec{F_{21}}=-\frac{\mu_0}{4\pi}i_1i_2\frac{\hat{r}}{r^2}\left[2(d\vec{\ell_1}\cdot ...
2
votes
0answers
48 views

Was Tesla familiar with Helmholtz, Maxwell, and Hertz (or vice versa)? [closed]

Was Tesla familiar with the theories or experiments of Helmholtz, Maxwell, and Hertz (or vice versa)?
2
votes
1answer
190 views

A James Clerk Maxwell Disproof

One of my favorite physicists to learn about was James Clerk Maxwell, for the fact that he unified the study of E&M in physics and he would often disprove theories that did not work as a ...
2
votes
1answer
129 views

Was Max Born the first to notice a connection between quantum mechanics and randomness?

Max Born introduced the Born Rule in a paper from 1926. But was this really the first time that a connection between quantum mechanics and randomness was noticed? Today, quantum mechanics and ...
3
votes
4answers
741 views

Newton's first law: is his concept of (force of ) inertia still useful and used?

The force of inertia is the property common to all bodies that remain in their state, either at rest or in motion, unless some external cause is introduced to make them alter this state. That ...
6
votes
1answer
123 views

Who developed the phase space path integral?

The original path integral introducted by Feynman is $$ \lim_{N\to +\infty} \int \left\{\prod_{n=1}^{N-1} \frac{\mathrm{d}q_n}{\sqrt{2 \pi i \hslash \varepsilon}} \right\} ...
3
votes
1answer
300 views

Why isn't the quark charge taken as primitive?

Why are electrons taken implicitly to be the elementary charge? It would save a lot of fractions in particle physics problems.
1
vote
1answer
180 views

Dirac's remark that inspired Feynman when formulating path integral

When Feynman was trying to formulate path integral of quantum mechanics, he was inspired by Dirac's remark which roughly states that $e^{i\frac{S}{\hbar}}$corresponds to the transition amplitude, ...
14
votes
5answers
1k views

What problems with Electromagnetism led Einstein to the Special Theory of Relativity?

I have often heard it said that several problems in the theory of electromagnetism as described by Maxwell's equations led Einstein to his theory of Special Relativity. What exactly were these ...
19
votes
7answers
1k views

How was the formula for kinetic energy found, and who found it?

My questions mostly concern the history of physics. Who found the formula for kinetic energy $E_k =\frac{1}{2}mv^{2}$ and how was this formula actually discovered? I've recently watched Leonard ...