Questions tagged [terminology]

Use this for questions relating to the proper use of physics terminology or nomenclature.

1,423 questions
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Is there any consensus on what is meant by Lagrange's equations of the first kind?

Is there any consensus on what is meant by Lagrange's equations of the first kind? Joos and Freeman define them as follows: Coordinates are given in terms of a rectangular Cartesian coordinate ...
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What is the difference between “uniform” distribution and “even” distribution?

I was reading a question in mechanics where it was written that mass of the rod is evenly distributed, but it was supposed to be "uniformly distributed". What is the difference between "uniform" ...
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What's the difference between a convection and a polarization electric field?

In the ionosphere and magnetosphere communities, studies frequently refer to the "convection electric field" and the "polarization electric field". What is the relationship between them, and what are ...
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Isn't end-centered monoclinic same as monoclinic?

monoclinic is simply an extruded parallelogram. If we place end centers on parallelogram faces then taking half of both diagonals and same height as before as 3 basis, its the same. That's what I ...
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I'm reading the paper "The Problem of the Interrelation of Coordination and Localization", which is written by N. Bernstein. The paper says, The degree of tension of a muscle is a function, in the ...
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Mathematical term for the on/off gradient functions in MRI imaging

The slice selection gradients, as well as the phase and frequency, in MRI imaging are traditionally represented by on/off box or rectangular symbols: or My question is what is the mathematical name ...
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Truncated $N$-Point Functions

In Quantum Field Theory, truncated N-Point functions (or truncated Green's functions) are the N-Point functions of diagrams with their external legs chopped off. I was told that the truncated N-Point ...
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What does “as small as a fraction of an angstrom” mean?

I was reading my school textbook in which the following statement was given: The resolution of such an electron microscope is limited finally by the fact that electrons can also behave as waves! (...
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What is kinetic theory?

What is kinetic theory? I am taking a course on fluid dynamics right now, and I have been wondering about one thing for some time now. We have three ways to look at a gas ($N$ particles): 1) ...
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Meaning of the word 'canonical' in physics

I often encounter the term canonical in my study of physics. What does it mean? There is canonical momentum, canonical transformations and I have even heard the phrase 'proving something more ...
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Is there a name for this phenomenon?

Imagine I have a cylindrical pipe closed on both ends with lids. I fill it with sand and compress the sand tightly. Now I hold the cylinder vertically and remove the bottom lid. The sand will counter ...
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Four-vectors in relativity

I have a question about specifically whether the components of a 4-vector could depend on the position $x \in \mathcal{R}^4$, where I denote Minkowski space with $\mathcal{R}^4$. I know that the ...
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Quantum state space constructing operator

If I use British money the amounts I can have are isomorphic to $\mathbb{Z}_{\geq0}$ (in pennies). If I also use Australian money, if I want to think about the amount I have in total, I can use ...
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Quasi Static Reversibility Theorem

As far as I know, the definition of a reversible process is simply "a process that can be reversed". Meaning, that for an isolated global system containing the subsystem in question, its thermodynamic ...
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Why is equipartition law called a theorem too, in some books? [closed]

In some books, the equipartition law is called a theorem. But a law is an observation, and cannot be proved. On the other hand, a theorem is something established using earlier assertions. So what ...
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What does it mean for event generation and event reconstruction in Experimental Particle physics? [closed]

I want to do data analysis and there are some processes called event generation and event reconstruction. I want to know these terms that what does it mean in particle collider? Please guide me.
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Large Lorentz Boost

I understand the general concept of a lorentz transformation and a lorentz boost. What does it mean for a lorentz boost to be large however? My current guess is that this is referring to a large ...
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Is $\delta(r-ct)/4\pi r$, the 3D wave equation elementary solution, a transverse or longitudinal wave?

Background: https://en.wikipedia.org/wiki/Longitudinal_wave 'Longitudinal waves are waves in which the displacement of the medium is in the same direction as, or the opposite direction to, the ...
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What is the 'state space' of a quantum field theory called?

This is just a terminological question, not a question about reality or mathematics. I often want to talk about state spaces in quantum field theory. For example the space of [all possible vector ...
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“Now-plane” of a particle

I am currently reading the book "Classical charge particle" by Fritz Rohrlich, and I struggle a lot with the appendix "space-like planes and Gauss's integral theorem". He says "the world line of a ...
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Is quantum field theory a field theory of quantum mechanics or a quantum theory of fields?

Quantum field theory can describe and extend phenomena of classical fields, such as electromagnetism. I had assumed for a long time that it was itself a "field theory", by which I mean it is a set of ...