Newest Questions
244,124 questions
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Apparent contradiction in wavelength of standing waves in an open-ended organ pipe
Recently I came across the "end correction" in organ pipes, and got to know that it affected only displacement waves, i.e it shifts the antinode of these displacement waves further outward.
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Is this a notational mistake?
I was reading Dirac's original paper from 1928, and I noticed this equation
Is it just me, or it's supposed to be
$$\rho_{mn} = -\frac{e}{2mc^2}\lbrace ih (\psi_m \frac{\partial \bar{\psi_n}}{\...
- 252
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2
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106
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Enthalpy of An Ideal Gas
I have started self studying statistical physics for a research project. I have a background in pure mathematics, and am having some trouble understanding differentials.
To learn, I am using L.E. ...
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Is the magnitude of error in a measurement inversely proportional to the number of observations taken?
I came across the following question.
A research worker takes 100 observations in an experiment. If he repeats the experiment by taking 500 observations, how is the probable error affected?
The ...
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Repulsive sheet through a uniform gas
I'm working on a pretty niche cosmological system where a (gravitationally) repulsive "sheet", say parallel to the xy plane, is moving through a uniform gas with temperature $T$ and density $...
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6
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2
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688
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In quantum mechanics, why is the perturbed state orthogonal to the unperturbed state?
In perturbation theory, we may write the full wavefunction as
$$|\Psi\rangle = |\psi^0\rangle + \varepsilon |\psi^1\rangle + \mathcal O(\varepsilon^2).\tag{1}$$
Here I'm focusing on a single energy ...
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Dog chasing a cat problem: Minimum distance [closed]
A cat sitting in a field suddenly sees a standing dog. To save it's life cat runs away in a straight line with constant speed u . Without any time lag, the dog starts with same constant speed u. At ...
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68
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How can a superdeterministic universe deal with (classical) chaos?
I'm aware that "superdeterminism" is sometimes misinterpreted, so I just want to provide a bit of context about how I understand the term:
When I was first learning about how a "hidden ...
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Will quantum computing trigger a cryptocurrency boom or crash? [closed]
I asked Microsoft Copilot and this was its response:
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Will quantum computing trigger a cryptocurrency boom or crash?
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Quantum computing could have a major impact on cryptocurrency, but whether it ...
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2
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Does beat frequency work differently when the beat frequency is greater than one of the initial frequencies?
I'm studying beats right now, and I know that, given two waves, the beat frequency can be found by taking the absolute value of the difference between the frequencies of those waves. I assumed that a ...
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105
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Thought experiment about force being transmitted at the speed of light [duplicate]
In a thought experiment, imagine I have a 1 light year long cylinder of matter that extends radially up from the surface of the Earth held in my hand. Just below my hand on a table is a spring scale ...
- 581
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How to catch up in my physics class? [closed]
I am currently a freshman physics and ME major. I am taking the first physics course called physics for science and engr majors I. It is the first non intro physics class. It goes over the basics like ...
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I Need Reviewer for a Physics paper call Kinetic Substrate Model (KSM) [closed]
Request for Review and Feedback: The Kinetic Substrate Model (KSM)
I’m seeking informed critique and discussion on a unification framework I’ve developed over several decades, called the Kinetic ...
5
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1
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226
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Calculation of spectra from a priori QFT/QED
I am a beginner at QFT, and I've been looking through the questions on this site (such as this one and this one) but I've not found one that satisfactorily answers the question of how to reproduce the ...
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Deriving the equation for conformal boundary states in 2D BCFT?
The boundary state $|B\rangle$ in boundary conformal field theory (BCFT) is a state that satisfies the following equation
$$
(L_n-\bar L_{-n})|B\rangle=0,\quad (\text{for all}~ n\in\mathbb{Z}),\tag{1}
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