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Questions tagged [terminology]

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

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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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2answers
168 views

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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1answer
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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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When was the phrase “beta function” of renormalization first used?

My question is a historical one: when was the phrase "beta function", as it pertains to the renormalization-group equations, used in physics? I am talking about this beta function: $$\beta_g\equiv \...
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What does Carlo Rovelli mean by “blurring”?

In Rovelli's book The Order of Time, he often refers to blurring. Can you help me to understand what he means? He says we observe the universe from within it, interacting with a minuscule portion ...
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1answer
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What is the difference between a quadrivector and a 4-vector? [closed]

What is the difference between a quadrivector and a 4-vector? Why is the square of a 4-vector equal to $t^2+x^2+y^2+z^2$ while the square of a quadrivector is equal to $t^2-x^2-y^2-z^2$? Aren't they ...
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130 views

What is a fuzzy space?

Can someone give a down-to-earth explanation of what is a fuzzy space? (As known from M-theory and noncommutative geometry)
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76 views

Terminology for how bendable an object is and what affects the bendable-ness of an object

I was wondering what the term is for how bendable an object is. Also, does this feature vary depending on the thickness of the object? Say, for example, I want to know how bendable a ruler is. Does ...
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What is meant by finite harmonic oscillator?

What does it mean to take finite harmonic oscillator, In research article "http://iopscience.iop.org/article/10.1088/1367-2630/17/11/113015 ", we were finding effective number of cobosons in ...
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1answer
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Should the rest frame of a lab positioned on a gravitating body be considered an inertial frame in special relativity or not?

In Newtonian Mechanics, the rest frame of a lab on the Earth is considered to be (approximately) an inertial frame. The fact that a thrown ball is not moving on a straight line corresponds to the ...
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Why is quantum mechanics called quantum *mechanics*? [closed]

At least a few books have "Quantum Mechanics" in their title, e.g., Sakurai's Modern Quantum Mechanics. However, I don't think measuring spin, which is "the" way of introducing quantum mechanics, ...
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What is a hypercomplex quantity?

An extract from the book "Quantum Mechanics and the Path Integrals" by Richard P. Feynman and A. R. Hibbs: We can state the correct law for $P(x)$ mathematically by saying that $P(x)$ is the ...
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130 views

What is meant by the absolute scale of the neutrino mass?

In this review titled "Pieces of the Flavour Puzzle" the author Ferruccio Feruglio wrote in the introduction that "The origin of the parameters in the flavour sector of the Standard Model (SM), ...
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1answer
139 views

Is there a standard convention for whether the term “handedness” refers to helicity or chirality?

I was under the impression that the "handedness" of a massive spin-1/2 particle refers to its chirality rather than its helicity. This answer, this one and Srednicki's QFT textbook seem to use the ...
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1answer
74 views

Models in physics [closed]

As I said in another question I am just a physics enthusiast so I am sorry for my very poor knowledge. What is meant by models in physics? what is their function and why physicists imply them? Are ...
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1answer
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What is the term for the light-sensitive metals in the photoelectric effect?

Can anyone please tell me the term used to refer to metals such as those used in photoelectric effect which can generate a current from light?
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1answer
68 views

Adiabatic Availability?

In the textbook "Thermodynamics: Foundations and Applications" by Elias P. Gyftopoulas and Gian Paolo Beretta (Dover). In chapter 5, on page 73 (section 5.3) the book says: Adiabatic availability ...
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1answer
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How to concisely state 'atmospheric conditions' without being ambiguous with STP?

I'm conducting an experiment in an open system, so the temperature and pressure is equal to that of the atmosphere at that time. However, it is not equal to STP conditions of $273 \; \mathrm{K}$ and $...
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About the quadratures method

in the Classical Mechanics (2nd. Ed.) book of Herbert Goldstein, p. 75 it says: "Equations 3-18 and 3-20 are the two remaining integrations, and formally the problem has been reduced to quadratures..."...
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1answer
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What is the wave field functional?

I was reading on some QFT and I came across the following paragraph: In the same way that a generic state $|\psi\rangle$ of a particle can be described by giving its overlap with all the possible ...
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2answers
213 views

Modes in optical fibers

I am trying to understand the modes in step-index optical fibers and I saw that they say the electric field distribution in the core and cladding is as bellow. my question is that which component of ...
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4answers
891 views

Shouldn't “speed of light” really be “speed of electromagnetic waves”?

Since all electromagnetic waves travel at the speed of light ... shouldn't its name be Speed of Electromagnetic wave?
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If an object moves at constant speed, does it necessarily have constant velocity? [closed]

If an object moves at constant speed, does it necessarily have constant velocity?
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Is there a term for the study of asteroids?

I'm trying to find the name for the academic specialty of studying asteroids, but I can't seem to find any. For example, there is a distinct wikipedia page for "Planet" vs "Planetary science". Is ...
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What is gradient-flow modified operators in thermal gauge theory?

This is going to be a very "soft-question". I do not fully understand German, so I am not sure if "Korrelationsfunktionen mit Gradientfluss modifizierten Operatoren bei endlicher Temperatur in ...
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2answers
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What are pre collisions and post collisions in forces and momentum?

What are pre collision and post collision exactly? I assume it is before collision and after collision. I can not find an answer on google.
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4answers
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Is there an agreed upon physics definition of the term 'speed'?--for example, can it be negative?

The term speed is commonly defined as follows: https://www.physicsclassroom.com/class/1DKin/Lesson-1/Scalars-and-Vectors Speed, being a scalar quantity, is the rate at which an object covers ...
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1answer
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Kepler's Second Law: Why do we calculate the area of a triangle rather than the area of a sector?

Kepler's Second Law states that equal areas are swept in equal times. When calculating this area, why do we use the formula for the area of a triangle rather than the area of a sector?
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1answer
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What is NLL in MC of SM/BSM?

I know that NLO represents using Next to Leading Order Feynman diagrams for a more accurate calculation. And similarly NNLO being Next to Next to Leading Oder. I am wondering what NLL is an acronym ...
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1answer
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Wess-Zumino model: simplified vs non-simplified?

According to Ryder Quantum Field Theory page 440 the "simplified Wess-Zumino model" has the lagrangian $$ \mathscr{L} = \frac{1}{2}(\partial_\mu A)^2 + \frac{1}{2}(\partial_\mu B)^2 + \frac{1}{4} \...
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1answer
69 views

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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1answer
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about the muscle's tension's variables

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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2answers
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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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1answer
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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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1answer
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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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2answers
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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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1answer
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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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1answer
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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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77 views

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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3answers
223 views

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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1answer
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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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2answers
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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 ...
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1answer
197 views

What does 'Truth-level' mean in Particle Physics? [duplicate]

I am sorry to ask an obvious question but I have tried looking this up on Google and cannot get an answer. In particle physics, when it is said that something is 'truth-level', what does that mean? ...
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What to call an object which is in motion but not accelerating?

I began learning about acceleration and according to the source i learned from an object only accelerates when there is change in vel. &/ direction... what i am wondering is what do you call it ...