Questions tagged [physics]
For questions about the scientific discipline that concerns itself with analysing the laws of nature in full generality
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What was the vis viva controversy, including its philosophical aspects?
Leibniz's concept of vis visa (literally translated as living force) was a precursor to our modern concept of kinetic energy. His formula for it was close to the modern non-relativistic one: $mv^2$, ...
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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 ...
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How did Young perform his double slit experiment?
Thomas Young is famous for his double slit experiment, but I can't seem to find his experimental setup (such as how is prepared the light before it went through the apparatus. Does anyone know his ...
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How did Planck derive the black body radiation formula without using the Bose statistics?
It is so funny that science never develops as in the textbooks. Bose only introduced his statistics in 1924, so Planck could not possibly have used it to derive the radiation formula in 1900. So how ...
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What 19th century developments contributed to the General theory of Relativity?
Regarding General Theory of Relativity, I'm interested to find out whether there are some contributors to this theory in 19th century or not. In fact I want to know whether there are some physicists ...
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What is the history of electric current and resistance?
Thomas Kuhn writes in The Structure of Scientific Revolutions
Part of what the acceptance of Ohm’s Law demanded was a redefinition of both ‘current’ and ‘resistance’; if those terms had continued ...
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Whose shoulders did Newton stand on?
In a letter to Robert Hooke in 1676, Newton wrote:
If I have seen further it is by standing on the shoulders of giants.
Do we know which giants Newton was referring to? And was he referring to a ...
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How was Einstein led to make a contact with Differential Geometry for his theory of General Relativity?
General Relativity was developed with Differential Geometry as the tool.
How was Einstein led to make a contact with Differential Geometry for his theory of General Relativity? Who suggested him to ...
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How did Kepler "guess" his third law from data?
It is amazing that Kepler determined his three laws by looking at data, without a calculator and using only pen and paper. It is conceivable how he proved his laws described the data after he had ...
Joshua Benabou
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Why don't we learn Buridan's laws of motion?
My question is why has Jean Buridan faded into obscurity while Newton is venerated as a God by scientists? Here is a description of Buridan's impetus theory:
The concept of inertia was alien to the ...
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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. ...
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What are the major flaws of the “caloric” theory of heat?
I was reading about the history of thermodynamics and came across Lavoisier's idea of heat. He proposed that heat was a fluid. I am curious to know what are the major drawbacks of this theory. I know ...
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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....
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How did Newton explain his interference rings without wave optics?
Nowadays we know it is a consequence of the wave property of light. But ironically it was discovered by Newton who held the particle point-of-view of light. So how did he explain his discovery?
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Is Coulomb's law the earliest mathematical formula describing electricity?
Is Coulomb's law the earliest formal equation of electricity?
Before Coulomb, many scientists and engineers conducted experiments of electricity.
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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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When was the vector notation in physics and other sciences first introduced?
The vector notation in physics is a very compact and easy way to write things down, and according to Feynman it also saves print. When exactly did scientists realize that they were summarizing things ...
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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 ...
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When were the modern notions of work and energy created
Reading through Wikipedia says that Coriolis was the first to introduce the notion of work, described as "weight lifted through a height".
Our modern conception of work is of a force that realizes a ...
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Why is Einstein's mass-energy relation usually written as $E=mc^2$, and not $\Delta E=\Delta m c^2$?
Why is Einstein's mass-energy relation usually written as $E=mc^2$, and not $\Delta E=\Delta m c^2$?
When you calculate the energy $\Delta E$ released during nuclear fission, you take the difference ...
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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 ...
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Who first derived $a =v^2/r$
This is a basic formula in mechanics, which determines the acceleration of a particle performing uniform circular motion.
By who first derived it? In Newton's Principa, what one can find is that
$$...
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Was there any atomic model(s) that came between Bohr's and the actual beginning of Quantum Mechanics in early 20s?
Well, the question arose in the physics chat when slereah mentioned about it.
So, was there any prominent model that came to light after Bohr and before the actual beginning of Quantum Mechanics in ...
user1709
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How the law of inertia got discovered?
In the Feynman lectures, it is mentioned that [Vol 1; Gravitation]:
Galileo discovered a very remarkable fact about motion, which was
essential for understanding these laws. That is the principle ...
user3997
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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 ...
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How did scientists plot complicated graphs in the 19th century?
I am wondering how did Maxwell in the 19th century draw such figures as the one shown? What tools or procedures did he need?
Is it all compass and ruler drawing?
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Who discovered the covering homomorphism between SU(2) and SO(3)?
Who discovered this? It is quite nontrivial and very important in quantum mechanics.
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What data did Kepler work out his laws from?
It's well known that Kepler worked out his laws by fitting curves to Tycho Brahe's data on the trajectories of planets through the sky. What was this data? How does one record the trajectory of a ...
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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 ...
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Hidden agenda of the Galileo trial?
Redondi argued that Galileo's trial on heliocentrism was merely a show trial concealing the real objection against Galileo among the catholic establishment, which was his atomism thought to be at ...
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What was Einstein's motivation for relativity theory?
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 ...
user40003
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What is the origin of the $\hbar$ symbol?
Equations involving Planck's constant, $h ,$ are often simplified by instead writing them in terms of the reduced Planck's constant, $\hbar \equiv \frac{h}{2 \pi}.$ But where did the symbol for the ...
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Why did Einstein develop General Relativity?
I know that ultimately GR was validated by experiment. I'd like to know however, if there was any experimental discrepancy at the time that pointed to a conclusive flaw in Newtonian gravity, and which ...
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In which units did Sir Isaac Newton define force at that time as SI system didn't exist then?
Sir Isaac Newton led the foundation of his famous laws of motion during the 17th Century but at that time SI system hadn't existed. So in which units did he define force? Did he define it in some ...
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Where did Rayleigh derive the ultraviolet catastrophe?
Where can I find this paper:
J.W. Strutt, Verh. d. deutsch. phys. Ges. 2, 65 (1900).
It is presumably where Rayleigh derived the black-body radiation formula (the incorrect one that has ultraviolet ...
user2831
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Which book gives a thorough understanding on the scientific environment of antiquity?
I have started reading Rene Dugas' History of Mechanics book. I want to understand physics from the spectacle of seeing its intellectual evolution instead of directly jumping into its general theories/...
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Who was the first scientist to suggest that objects can keep moving without applied force?
In the old days Aristotels argued that object needs a force to keep going in 'space'. Some philosophers, Philoponus and Buridanus (?), later argued that there was a need for some kind of 'impetus'. ...
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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 ...
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Books on the History of Physics
I've just finished reading Quantum: Einstein, Bohr, and the Great Debate About the Nature of Reality by Manjit Kumar, which deals with the history of QM from Plank's quantisation for black body ...
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What made Einstein believe (or know) that time was affected by speed and gravity?
How did he come up with this idea before there was any experimental data to prove this?
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Who originally derived the general force law equation of force between current elements?
Wikipedia credits this to Maxwell. This derivation can be found in Maxwell's Treatise on Electricity and Magnetism vol. 2, part 4, ch. 2 (§§502-527). I went through the derivation and found two self ...
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Where did $P=VI$ come from?
Where did the basic physics law $P=VI$ come from? Here, $P$ is power, $V$ is voltage and $I$ is current. It doesn't have a name like Ohm's law, as far as I could find. So where did it originally come ...
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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 ...
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How was the first parabolic telescope mirror made, and how was it used, and for what kind of telescope was this work done?
This answer to When was the first true Gregorian telescope built? explains:
Newtonian uses one concave and one flat mirror (or just one concave).
Gregorian uses two concave mirrors, and
Cassegrain ...
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How did people figure out the formula for mechanical work, and related it to energy?
What developments led to the definition of Work as the dot product of Force and Displacement vectors?
I did some searching but couldn't find a satisfying answer. According to what I have read, the ...
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"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 ...
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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 ...
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Why is Maxwell and not Ampère credited for unifying electricity and magnetism?
Ampère, a half century before Maxwell, theorized that magnetism was caused by electrical currents. So, why is Maxwell and not Ampère credited for unifying electricity and magnetism?
(cf. the question ...
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Who introduced velocity potential?
Wikipedia cites John Anderson’s A History of Aerodynamics and says that velocity potential was introduced by Lagrange in 1788. However, I could trace it at least to Euler 1752, where he published his ...
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Why is differentiation under the integral sign named Feynman's trick?
It's a simple enough result I would have been unsurprised if it weren't named for anyone at all. I certainly find it odd it's named for a relatively modern physicist rather than an early-calculus ...
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