Questions tagged [quantum-mechanics]
The branch of physics that relates to the behavior of objects, typically particles, on small scales. Probability is very important in quantum mechanics.
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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 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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Did wave optics anticipate quantum mechanics?
I heard in wave optics and electromagnetism that Hamilton could have discovered the Schrödinger equation, or that he was the first man who used the expression
$$ \Psi(x)= \exp(i S(x)/\hbar)\,. $$
I ...
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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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Why were 20th Century German scientists so impressive?
German (and Austrian) scientists of the late 19th - early 20th centuries seem to have been the backbone of most of modern physics - namely quantum theory/mechanics. The following are a few predominant ...
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What is the original source for Einstein's description of entanglement as "Spooky Action at a Distance"?
Try as I may, I cannot find the original source where Einstein described entanglement as "Spooky Action at the Distance." The work "spooky" is not in the 1935 EPR paper, which was written in English ...
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When was the quantization of spin discovered?
When was the fact that a spin could only have values $S = n/2$? I cannot find any source that says when.
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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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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 ...
Danu♦
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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 ...
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Who was the first to say "Shut up and calculate!"?
The best thing I could find on the internet was this apparently forgotten article from 12 years ago.
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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 ...
user466
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Who solved the particle-in-a-box model first?
I got curious who invented the particle-in-a-box model first. It is really simple and intuitive. I was googling to find the original author who suggested it but I only get textbook or webpages as ...
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What was the first journal to have Feynman Diagrams?
I'm writing a paper on the history of Feynman diagrams and am having trouble finding the first paper published by Feynman which features a calculation done with Feynman Diagrams.
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Who was first to observe or detect photons in the double slit experiment, and how did they do that?
In the early 1800s Thomas Young introduced (a thought-?) experiment also known as the two slit experiment. He discovered the strange way photons created a interference pattern on a screen.
There is ...
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How did Born come up with the Canonical Commutation relation ($\hat X \hat P-\hat P\hat X=i\hbar$)?
All answers to questions like this dodge the question by saying it's a postulate of Matrix Mechanics, so let me rephrase it. Instead of how to derive the CCR, how does it follow from Heisenberg's ...
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How did $SU(2)$ came into physics?
It is natural for physicists to consider the group $SO(3)$. Presumably, $SU(2)$ came into physics because of quantum mechanics. How did people realize that when studying rotation of a physical system, ...
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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....
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History of delta barrier in quantum mechanics
I'm interested in finding something out about the history of the problem of the delta potential barrier in quantum mechanics.
Which was the first study to propose this problem, and perhaps any ...
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Degenerate States in Quantum Mechanics
In his book on quantum mechanics in the chapter on perturbation theory Dirac says in a footnote:
A system with only one stationary state belonging to each energy-level is often called non-...
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Who first noted the connection between Heisenberg's uncertainty principle and the Fourier transform?
Who first noted the connection between Heisenberg's uncertainty principle and the Fourier transform?
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What did Einstein say about the Dirac equation?
The wiki article on Dirac quotes Einstein as saying of Dirac
I have trouble with Dirac. This balancing on the dizzying path between genius and madness is awful.
and
I don't understand Dirac at all.
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Who solved the quantum harmonic oscillator?
In continuation of this question, Who introduced the creation and annihilation operators for the harmonic oscillator?, I got curious who came up with the quantum harmonic oscillator originally.
I am ...
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Are Wheeler's It from Bit/Participatory Universe and the Multiverse related?
Could I ask you for the relation between Wheeler's ideas and the multiverse? Do you know if these are related?
I ask you this because I found this very interesting article written by Kip Thorne with ...
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Max Planck and energy quantization idea
Did Planck have an intuition behind the idea of energy quantization of atomic oscillators and radiation, or was it just a mathematical trick to derive his distribution law?
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Planck's quantization idea
First of All, I doubt there has ever been any new idea that did not involve intuition.
However, most textbooks suggest that the quantization idea was just a mathematical trick, that Planck introduced ...
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