Questions tagged [terminology]

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

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39 views

Einstein solid degree of freedom

I was studying from Schroeder's thermal physics book. When it talks about Einstein solids it says that they have 2 degrees of freedom thus $U=NkT$ However, I thought when we talk about Einstein ...
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2answers
54 views

What is meant by “linear” in non-equilibrium thermodynamics?

I'm trying to learn a bit about non-equilibrium thermodynamics, and am currently reading de Groot and Mazur. In it, there is a quote right in the beginning, talking about the phenomenological ...
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28 views

Difference between time series and trajectory terminology

What is the difference between trajectory and time series? To me both seem the same thing. In the 3D diagram (cube picture on left of Fig.2 from the paper titled “Review and comparative evaluation of ...
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2answers
83 views

Why is particle physics called high energy physics? [duplicate]

The highest energy accelerator till date is the LHC which operates at an energy scale of perhaps 10-100 TeV. In SI units this is about $\sim 10^{-6}-10^{-5}$ Joule which is several orders of magnitude ...
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63 views

Technical question on definition of free fall

Free fall is any motion of a body where gravity is the only acceleration acting upon it. But, what if I threw an object from a certain altitude, and had two jetpacks put on it , one providing ...
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2answers
55 views

What does 'per unit frequency' refer to?

We were discussing Kirchoff's theorem on blackbody radiation in class today and the equation was: $$e_{f}= J(f,T)$$ $e_f$ was defined as power per unit area per unit frequency. What does per unit ...
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65 views

What's the difference between canonical quantization and second quantization?

I am wondering the difference between the canonical quantization and the second quantization in quantum field theory. For example, a harmonic chain, one can write down its lagrangian density $\...
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45 views

System in Lieb and Yngvason's paper [closed]

I'm reading The Physics and Mathematics of the Second Law of Thermodynamics and have a question. In A. Basic concepts 1. Systems and their state spaces, the term system is formally introduced and one ...
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2answers
93 views

$n$-body problem = many-body problem? [closed]

Are the terms "$n$-body problem" and "many-body problem" synonymous? Or does one refer to a numerical problem an the other to an analytical problem?
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17 views

Reversed effective force in D'Alembert's Principle [duplicate]

In D'Alembert's Principle,what is reversed effective forces and how to determine it's direction?
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1answer
59 views

What is the difference between degree celsius and celsius degree? [duplicate]

It seems similar but can you guys please answer it that what is a specific difference between degree celsius and celsius degree?
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24 views

What is the static exchange approximation?

In this paper, on the 4th page (and throughout), they talk about studying electron-helium scattering in the "static-exchange approximation". I have scoured the literature and have not been able to ...
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46 views

Dimension of the candela unit: What does J stand for? [migrated]

The J symbol can represent the unit of energy but it's also the symbol for the dimension of the candela (or luminous intensity). For the energy unit, it clearly comes from the family name of the ...
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62 views

Terminology for time derivative of speed (not velocity)

Is there any standard terminology for the derivative of the magnitude of velocity with respect to time (suitable for use in first-year Calculus)? The word ‘acceleration’, in its technical sense, is ...
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4answers
140 views

Is the notion of 'weight of Earth' meaningless?

I am not talking about the distinction between mass and weight, just the concept of 'weight'. In University physics (book by Young & Freedman, 14th Ed.) it is given that the weight of an object ...
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3answers
53 views

Is a rotating object moving or stationary?

Because it rotates in situ, its center of mass does not move, so it is static, but it is rotating, so it is not static, then is it static or moving?
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36 views

Is the designation “chemical reaction” right for vibrational and electronic excitation of particles?

I'm currently doing my Master's thesis, which focuses on Atmosphere Reentry Thermodynamics and Kinetics. Due to the importance of this work, I would like to use the best terms to describe any ...
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1answer
66 views

If we say “an object is at rest,” can we also say “the object is moving at a constant velocity?” [closed]

If we say "an object is at rest," can we also say "the object is moving at a constant velocity?" Of course, the constant velocity would be zero, so it's mathematically sound. However, the wording ...
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41 views

What “luminosity distance” means in a general spacetime?

In the paper "Asymptotic Symmetries in Gravitational Theory" by R. Sachs from 1962, the author says the following: In analyzing gravitational fields it is sometimes useful to introduce coordinates ...
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28 views

What is meant by the vacuum structure of ABJM theory?

I was reading the paper Large $N$ behavior of mass deformed ABJM theory. It talks about the vacuum structure of the (mass deformed) ABJM thoery. What does vacuum structure mean in general or in ...
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4answers
1k views

What is the difference between uniform velocity and constant velocity? [closed]

I think that uniform velocity implies constant speed but not constant direction. while constant velocity implies constant speed without any changes in direction. Both tell us that there's no ...
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40 views

What is Rectangular Simple Harmonic Motion (SHM)?

While studying Simple Harmonic Motion and Lissajous figure, I found a term called Rectangular SHM. But what is it actually? Is it something like square wave? What is the difference between Linear and ...
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7 views

Terms time resolved vs. stroboscopic measurements

I use the term stroboscopic for an experiment, where the stroboscopic effect is part of the experimental setup. And I call an experiment a ...
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1answer
34 views

Abelian and non-Abelian holonomies

I read the article Geometric Manipulation of Trapped Ions for Quantum Computation, and it mentioned “Abelian and non-Abelian geometric operations (holonomies)”. I know what is holonomy, and what is ...
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63 views

Are there names for Helium (He) emission lines like the Lyman/Balmer/Paschen series in Hydrogen?

Just wondering if helium emission lines have names like hydrogen lines. For instance the Balmer series is: $$H_{\alpha}, H_{\beta}, H_{\gamma}, H_{\delta}...$$ The Lyman series is: $$L_{\alpha}, ...
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48 views

What do we really mean by the word “light”? [closed]

Does the term "light" refer to any electromagnetic wave or just the visible spectrum?
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18 views

What is an electrified channel?

I've been asked to create a sketch of an electrified channel. I've never heard of this terminology before. I tried to Google it and it came up with either guitar related answers, or a few about ...
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1answer
27 views

What is the difference between longitudinal chromatic aberration and spherochromatism?

In lens design textbooks, a distinction is often made between longitudinal chromatic aberration and spherochromatism. (See for instance Kingslake's lens design book.) What is simple way to understand ...
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2answers
58 views

“Energy transfer” and “Energy transport” [closed]

Are the terms "energy transfer" and "energy transport" sometimes or always interchangeable? My own surmise is that the term "energy transfer" is slightly more general: "energy transport" refers to ...
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1answer
35 views

Pseudotensors for describing physical quantities

I have been reading about tensors from Mathematical methods for Physics and Engineering, by K.F. Riley, M.P. Hobson and S.J. Bence. And there are a couple of things i am not getting. On page 949 (...
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Symbolizing frequency as $v$

In my school textbook $v$ is symbolized to the frequency of the wave. Is that correct? I also saw this convention used in Chemistry: The Central Science By Theodore L. Brown, H. Eugene LeMay Jr
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2answers
73 views

What does `weakly gravitating' mean?

When relativists like Bousso (see for instance https://arxiv.org/abs/hep-th/0203101) talk about `weakly gravitating systems', what sense of weak gravity is usually meant? (1) Post-Newtonian ...
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1answer
36 views

What is a pseudopure state?

In the paper titled "Experimental Implementation of the Quantum Baker’s Map" by Weinstein et al. (Phys. Rev. Let. 89 (2002)), the author says something like [...] the pseudopure state corresponding ...
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2answers
155 views

Difference between Oscillatory motion and vibratory motion

What is the difference between oscillatory motion and vibratory motion. I have read in my book that "If the amplitude of oscillatory motion is extremely small,the motion is called vibratory motion". ...
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107 views

What is the name of the formula?

What is the name of this formula? $$ G_{\mu\nu} = 8 \pi T_{\mu\nu} $$
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34 views

Interaction picture counter rotating terms

In the interaction picture, we often do the rotating wave approximation where terms like $e^{i(\omega_1 + \omega_2)t}$ are ignored because they represent rapidly oscillating terms which ends up ...
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9answers
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The instant an accelerating object has zero speed, is it speeding up, slowing down, or neither?

This problem is from Khan Academy. Specifically for the blue point circled in red, the answer is that at this blue point, the object is neither speeding up nor slowing down. When I think about the ...
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38 views

In what sense $Z_\mu^0$ is orthogonal to $A_\mu$?

I am reading Standard model. Please explain in what sense the $Z$-boson $$Z_\mu^0=(g^2+g^{\prime 2})^{-1/2}(g A^3_\mu-g^\prime B_\mu)$$ is an orthogonal linear combination of the photon $$A_\mu=(g^2+...
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1answer
75 views

What is a gauge (for someone who has not studied gauge theory)? [duplicate]

I am taking a Quantum Mechanics II course and we were studying the relativistic corrections to the hydrogen atoms in perturbation theory. I was looking at the assignment, and a question is as follows: ...
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1answer
59 views

What is the area of physics/science called that deals with fundamental limits of computation?

I am interested in learning about the fundamental limits of computation and in particular would like to read textbooks on the subject if they exist. My background is in maths and computer science - I ...
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3answers
80 views

Understanding quantum mechanics “picture” terms

I was reading various sources and a have some questions. The "Schrödinger picture" is the same thing as "Schrödinger wave formulation"? Is "Heisenberg picture" the same thing as "Heisenberg matrix ...
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2answers
108 views

Formal name for the “pianology” objection towards contemporary particle physics direction of research?

In a popular science book, an interesting objection towards the current direction of particle physics was stated. I tried to search for more on this, but got nowhere. Since I assume this is not an ...
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1answer
44 views

Why the $L$ in an $RLC$ circuit? [duplicate]

I was studying for a differential equations class and came upon some information about $RLC$ circuits. I know the $R$ stands for resistance (makes sense) and $C$ stands for capacitor (this also makes ...
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17 views

What is meant by cubic symmetry with regard to thin films growth?

I am reading a paper on epitaxial thin film growth of an alloy and it mentions that for one conditions the films grow with a cubic symmetry and for another they have an in-plane anisotropy. I would ...
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1answer
63 views

Exact meaning of 'degree'

I wish to know if there is an exact meaning of degree in physics/math/chemistry. It is used in many cases and it is not clear to me which requirements must have an unit of measurements for carrying ...
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1answer
76 views

Why is the “fine structure” correction called that way?

I'm working on the fine structure correction to the Hydrogen atom. I have more of a conceptal, maybe historical question, why is this correction called this way? and why is the fine structure constant ...
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1answer
114 views

Difference between an electron wiggler and an undulator?

Both wigglers and undulators use periodic magnetic fields applied to stored relativistic electron beams to produce intense beams of UV or X-rays that can be used in a wide range of condensed matter ...
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2answers
43 views

Do the terms “damping constant” and “damping coefficient” have standard uses?

I've heard the terms "damping constant" and "damping coefficient" used to describe both the $c$ from the viscous damping force equation $F = -c\dot{x}$ and the $\gamma$ from the definition $\gamma = \...
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52 views

Why do terms in a field theory Lagrangian that are polynomial in the fields collectively called the “potential”?

Field theory Lagrangians are often of the form of a kinetic term plus a source term minus a potential term. How do we know that the potential term is a polynomial in the fields? On a related note why ...
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48 views

Difference between Postulate versus Law

In quantum mechanic, we have many different postulates. In classic mechanic, we have different laws. As long as I know that physics's laws are temporarily correct until an anomaly. But what is the ...