Questions tagged [terminology]

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

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134 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
187 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
76 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
54 views

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
73 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
32 views

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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1answer
64 views

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
98 views

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
261 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
1k 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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2k views

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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30 views

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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14 views

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
39 views

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
146 views

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
96 views

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
24 views

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
75 views

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
76 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
42 views

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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1answer
66 views

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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1answer
359 views

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
100 views

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
75 views

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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401 views

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
49 views

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
73 views

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
44 views

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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51 views

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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56 views

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
136 views

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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1answer
90 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
226 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
114 views

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
88 views

“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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2answers
176 views

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
239 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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2answers
128 views

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 ...
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0answers
56 views

Is gauge invariance the same as gauge symmetry?

I am studying Gauge theory using Wikipedia and need a little clarification on the difference between gauge symmetry and gauge invariance. For sure it has probably already been addressed on this site, ...
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2answers
73 views

Direction of temperature gradient while studying thermo electric effects

What is the direction of temperature gradient, when we study about thermoelectric power. And what is exactly meant by up and down the thermal gradient?
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1answer
105 views

Why is velocity gradient not called a velocity Jacobian?

I started thinking about the rate of deformation of fluid in the boundary layer. but here we consider only one of the components of the velocity vector (which is a scalar). But what about just general ...
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2answers
2k views

Why are hydrogen, helium and neon known as quantum gases in the mid-20th-century chemical literature?

So, while reading over equations of states, I learned that quantum gases do not conform to the same corresponding state behavior as normal fluids do. Why are these known as quantum gases and why do ...
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1answer
57 views

Feynman Probability lecture 6 - probability density graph

I'm trying to understand the 6-7 graph in the Feynman lecture 6 on Probability chapter (6–4) A probability distribution He says: "We plot $p(x)$ for three values of $N$ in Fig. 6–7. You will ...
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2answers
518 views

What is the difference between sound and vibration?

As far as I know, the only difference between sound and vibration is that sound propagates but vibration does not. In most cases, they are the same. Please help clarify these concepts.
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117 views

What is the exact difference between static pressure and temperature?

If temperature is the average amount of energy and static pressure is the amount of internal energy, wouldn't the static pressure be the same as the temperature?
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60 views

What is the correct name of this 'basis label operator'?

What is the correct name for this operator I am calling the 'basis label operator' which returns the constant function of the eigenvalue for all vectors in a (momentum) eigenspace? $$\hat{O} : \hat{O}...
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2answers
54 views

Why is optical contact called optical contact?

Why is optical contact called optical contact? whats the meaning of the 'optical', when the concept of optical contact bonding has nothing to do with optics.
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0answers
52 views

Is there a name for symmetry in which fermions and bosons are in identical adjoint representations?

In a Yang-Mills theory, with gauge group $G$, if the Fermions are in an adjoint representation then for every Fermion with "charge" $Q$ there is a boson with charge $Q$. i.e. there is no difference ...
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1answer
66 views

Continuum Physics

How distinct is fluid dynamics from continuum physics? I've heard it is a subset and by the definition of the subject's name, it seems likely to be the case. Can anyone please clarify?
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1answer
152 views

What does 'high-beta' mean for a fusion reactor?

I see the term 'high-beta' a lot, but cannot find a definition. When I type it into Google, I mostly see results about a Lockheed Martin fusion reactor project.....