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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42
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4answers
5k 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 ...
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When exactly (and why) did matrices become a part of the undergraduate curriculum?

Let me tell what I know about this. It is well-known that Heisenberg invented matrix multiplication himself, in his great paper that is considered part of the foundation of quantum mechanics. This was ...
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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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Did physicists around 1900 really believe they were close to “figuring it all out”?

I've encountered the claim that around the end of the 19th century, physicists believed that their understanding of the physical world was close to being complete. One example of this claim can be ...
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1answer
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What were the dominant non-atomic theories of matter in the 19th century?

From what I have read, the atomic theory of matter was cemented by a 1905 paper by Einstein in which he explained the erratic motion of a bit of pollen suspended in water using the assumption that ...
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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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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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How soon after or before the development of nuclear applications was waste disposal considered?

Nuclear applications—be it in the form of electricity production, weapon creation, etc.—inevitably involves radioactive waste. When was it realized that there might be a need for a specialized waste ...
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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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732 views

When did physics texts start to teach Kepler's $3/2$'s power law as a result of Newton's $1/r^2$ law of gravitation, rather than the other way around?

In modern physics textbooks, we teach Newton's laws of motion, then Newton's law of Universal Gravitation, and then Kepler's laws of planetary motion. Specifically, from the $1/r^2$ form of the ...
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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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In ancient times, how did people conclude that the shape of Earth is a sphere?

This is more of a philosophical question, but I want a mathematical explanation. During ancient times, it was well accepted that the surface of Earth was spherical. People first observed this when ...
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Did ancient/medieval non-European cultures have a concept of energy? If so, what are the similarities and differences to the modern concept?

For example, do we find something related to the modern energy concept in Ancient China, Ancient India, or the Islamic Golden Age? Among "similarities and differences", conservation is obviously ...
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Why did Tesla disagree with Einstein?

Both Tesla and Einstein were brilliant scientists. Tesla said the following on the theory of relativity in a 1935 New York Times interview: "The theory, wraps all these errors and fallacies and ...
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2answers
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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 ...
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2answers
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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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1answer
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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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874 views

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?
19
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1answer
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What cipher(s) did Isaac Newton use?

A number of sources including this one assert that Isaac Newton used encrypted messages to communicate some of his scientific discoveries, and as a way of establishing priority. What cipher(s) did he ...
18
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5answers
959 views

What led to the rise of Göttingen?

this is a counter part to my other question: What led to the fall of Göttingen?. Göttingen was a major university in which many famous physicists and mathematicians lived. It was located in ...
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2answers
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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 ...
18
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4answers
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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 ...
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Is this Einstein rejection letter fake?

So I found this on the internet the other day- Is this fake? Are there any ways to prove that it's fake? Does there, if any, exist any real copy of such a rejection letter?(Was Einstein ever ...
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1answer
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Did the Digges Telescope actually exist?

There are many claimants for the first telescope. Amongst these are the claims placed at the doors of Bacon and Digges. The Bacon claim is very sketchy, boiling down to one sentence and is easy to ...
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Did light bulb companies commission Planck to study black body radiation?

Background When introducing Planck's switch to looking at black-body radiation, a number of sources -- like MinutePhysics, the Economist, random online encyclopaedias and even here on HSM.SE (plus ...
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1answer
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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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What became of the Boltzmann-Zermelo debate about the second law of thermodynamics?

At the end of 19th century there was a lively discussion about the nature of the second law of thermodynamics, and its relation to Hamiltonian dynamics. Boltzmann developed a position that the second ...
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Why isn't Feynman's path integral taught more widely and earlier in today's academic physics curricula?

Anyone who has studied Feynman's path integral will know that it makes quantum mechanics more like classical mechanics. A student who has learned about the Lagrangian will easily understand the ...
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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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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 ...
15
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1answer
685 views

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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3answers
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Why is kg the standard unit for mass and not g in SI?

Why is $\mathrm{kg}$ the standard unit for mass and not $\mathrm{g}$? I know that there is the kilogramme des Archives which is a kilogram and not a gram. But originally on April 7, 1795 the gram was ...
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2answers
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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 ...
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2answers
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Who was the first to postulate that space was a vacuum?

The fact that space is a vacuum and that the Earth's atmosphere only extends a short way above the surface is accepted as obvious. However, there is nothing a priori obvious about it: you first have ...
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994 views

What is the story behind various uses of the word “spectrum”?

Here are five distinct uses of the word spectrum in physics and mathematics: Spectrum (optics): The range of colors in the rainbow Spectrum (particle physics): The range of electromagnetic ...
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3answers
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How did we come up with the name “atomic bomb”?

At first, my initiate question was: What is the difference between an atomic and a nuclear bomb?: Nuclear bombs are of two types — those that depend on fission, like atomic bombs, and those that ...
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4answers
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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 ...
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3answers
746 views

How did Galileo know that objects rolling down a ramp was an accurate model for free fall?

Galileo used balls rolling down ramps to study the relationship between time and distance traveled. However, without any knowledge of physics, it doesn't seem immediately obvious that the time-...
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7answers
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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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2answers
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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 ...
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1answer
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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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2answers
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Did Richard Feynman ever meet Stephen Hawking or comment on Hawking radiation?

I was just curious what Richard Feynman thought of Stephen Hawking's Hawking Radiation. Feynman was one of the developers of quantum field theory and Hawking's work would have been cutting edge on the ...
12
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3answers
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Why and when did some areas separate themselves from philosophy and some not?

When the Greeks invented science and mathematics in around 600 BC, it was considered as a part of philosophy. Thales of Miletus was a mathematician and philosopher. Aristotle was a philosopher, ...
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1answer
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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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2answers
181 views

What explanations are there for this strong spike in the use of 'angular momentum' in the 1960s?

A recent comment called my attention to the Google Ngram for 'angular momentum', which shows a very strong and rather sharp peak in the usage of the phrase shortly after 1960, followed by a steady ...
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2answers
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Why did Einstein stop publishing so many papers in Annalen der Physik?

In his early years (actually, straight through the early 1910s), Albert Einstein published a lot of papers in Annalen der Phyisk, a very old and prominent German scientific journal. However, this ...
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518 views

Has science fiction ever caused scientists to do real research?

Has science fiction ever caused scientists to do real research? Science fiction here means fiction that tries to explain things in the world rather than speculate about the future or unexplorable ...
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335 views

Was there early opposition to Newton's mechanics?

Scientific theories are rarely accepted immediately. Even if the evidence for a theory is impeccable, there will be some stragglers who resist it for lack of understanding. More interesting is when a ...
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3answers
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When was it first discovered (or comprehended) that air has weight?

When was it first discovered (or comprehended) that air has weight? Did the ancients know of this, or did they think that air is weightless?
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1answer
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When did people notice the special shapes of snowflakes, and when did they start to study them?

What was the first written account about snowflake shapes and when did physicists start to study the reasons why the form appears and how snowflakes form in the air? Is there any old book that ...

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