Skip to main content

Questions tagged [terminology]

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

Filter by
Sorted by
Tagged with
0 votes
0 answers
51 views

What is the difference between material time derivative and total time derivative of a tensor field? [closed]

I consider material coordintes as $(X_1(t),X_2(t),X_3(t),t_0),$ ($t_0$ arbitrary) and space coordinates as $(x_1(t),x_2(t),x_3(t),t).$ $\textbf{Remark.}$ I am interested just in dim=3. We consider a ...
pikunsia's user avatar
0 votes
1 answer
86 views

GR and Riemann Surfaces -- does the complex plane have anything to do with it?

I have only the vaguest understanding of Riemann Surfaces -- my sense is that Einstein used them in General Relativity because of their shape. But Riemann Surfaces I think are not just deformations of ...
releseabe's user avatar
  • 2,238
0 votes
0 answers
39 views

Absorption and emission spectrum terminology

Hi everyone recently i was looking for laser crystals and since I am an autodidact i was confused by the terminology and units of the optics domain. And specialy by the absorption and emission ...
Tintin's user avatar
  • 1
5 votes
2 answers
2k views

What does "DC" mean in gravitational physics?

I have came across a few works in gravitational physics using the term "DC" without further explanation of its meaning. For example, consider Strominger's 1703.05448, which states in p. 2 ...
Níckolas Alves's user avatar
0 votes
1 answer
34 views

How can I call a transformation where only the $z$-axis is modified by a function in each point?

What is called a transformation that maps $z \rightarrow |f(z)|\, z$, while the other axis stays the same? Is it a conformal transformation?
Aleph12345's user avatar
8 votes
1 answer
2k views

Is there a name for the number of '9's in numbers such as 0.999 (where it would be 3)?

I am doing an optics simulation involving transmission and reflection coefficients very close to 1, such as 0.999. While I was an undergraduate student, a professor mentioned that, in certain fields, ...
jcuk's user avatar
  • 93
0 votes
4 answers
85 views

What is the tangential component of any vector?

There's a statement I discovered in the book I am reading which says Kinetic energy changes only when speed changes and that happens when the resultant force has a tangential component. Does that ...
android's user avatar
  • 83
0 votes
1 answer
44 views

Is the set of possible elementary particle types equal to the set of all combinations of their properties? [closed]

I'm playing around with a mnemonic system for a fantasy language I'm working on, for remembering the properties of elementary particles. Each letter represents a unique sound. i a u These 3 are the &...
Lance's user avatar
  • 2,200
1 vote
1 answer
51 views

How to call ellipse packing structures?

My research group and I are trying to figure out what is the correct terminology for two different packing structures of 2D ellipses. The two structures are displayed below as Structure A and ...
JamesKUtterback's user avatar
0 votes
0 answers
22 views

What exactly are cohesive and adhesive forces?

Are cohesive and adhesive forces defined only when at least one of the interacting materials is a fluid?
Anvi Mahajan's user avatar
0 votes
1 answer
35 views

What type of variable would you classify $a, b, c$ etc shown in the picture? Would I just call them random, insignificant real values? [closed]

The variables don't really represent anything
Yifan YIN's user avatar
0 votes
0 answers
40 views

Is there a practical distinction between functions of state and functionals in thermodynamics?

In thermodynamics, and more precisely when talking about continuous systems, some sources [1, 2] introduce functionals of state: $$F[s(x), \dots]:=\int_VdV(x)f(s(x),\dots,x)$$ In order to derive ...
GvPStack's user avatar
0 votes
0 answers
48 views

Is there a name for Bohmian pilot wave theory with an ensemble of jockey particles?

In Bohmian QM, the wave function $\psi$ is moving a classical point particle around. Without effort, it could also move a large ensemble of particles (since there is no back reaction). Is there a name ...
Jos Bergervoet's user avatar
1 vote
1 answer
70 views

What is the difference between field and disturbance?

In my textbook Sears & Zemansky's University Physics, 15th ed, Page-399, it is written that, "A useful way to describe forces that act at a distance is in terms of a field. One object sets ...
Peter swift's user avatar
1 vote
1 answer
94 views

Why do people say that the $\Lambda$-CDM model has six independent parameters?

The Wikipedia article on the $\Lambda$-CDM model says that the model has six "independent parameters". It also says that the model has several "fixed" parameters and several "...
tparker's user avatar
  • 48.3k
0 votes
0 answers
58 views

What is the name of the transformation from one harmonic oscillator basis to another centered elsewhere?

If I have a harmonic oscillator basis centered at $x=2$, how do I rewrite it in terms of the harmonic oscillator basis centered at $x=0$? To be more specific: If $|\Psi_n\rangle$ is the $n$th ...
Idieh's user avatar
  • 71
14 votes
8 answers
4k views

Can motion be oscillatory but not periodic?

The equation of motion of a particle is $x = A \, \mathrm{cos}\left[(\alpha t)^2\right]$. What type of motion is it? The answer to this question in my textbook was: "Oscillatory but not periodic&...
Haider's user avatar
  • 159
0 votes
1 answer
52 views

When is an object no longer considered orbiting a celestial body during its descent?

During the Apollo mission, once the LM began its descent to the surface of the moon, was it still in orbit about the moon?
Bob516's user avatar
  • 269
1 vote
1 answer
33 views

Can the potential of a point charge be considered one-dimensional?

It is well known that,take infinity as 0 potential,the potential at position r of a point charge q placed at the origin is $$V = \frac{1}{4\pi \epsilon _0}\frac{q}{r}$$ it satisfies three dimensional ...
Toboraton's user avatar
  • 109
3 votes
1 answer
83 views

Why is the term 'Accuracy of 1 part in $x$' used?

My question stems from how we measure the accuracy of Caesium clocks. Most Caesium clocks are said to have an accuracy of '$1$ part in $10^{14}$.' I understand that the terminology means to convey ...
Smarika Singh's user avatar
0 votes
2 answers
65 views

Anode/cathode in an electrolytic capacitor during discharge?

Wikipedia says "an electrolytic capacitor is a capacitor whose anode or positive plate is made of a metal that forms an insulating oxide layer" (1, link). Elsewhere, wikipedia seems to ...
jkien's user avatar
  • 2,629
0 votes
1 answer
66 views

Name of metric used by Friedmann

In his original paper, Friedmann used the following dynamic and symmetrical metric: $$\mathrm{d}s^2=a(t)^2\left(\mathrm{d}\chi^2+\sin (\chi)^2\left(\mathrm{d}\theta^2+\sin (\theta)^2 \mathrm{d}\phi^2\...
Vincent ISOZ's user avatar
0 votes
1 answer
113 views

Renormalization group equation, the Callan-Symanzik equation, and renormalization group flow

I am learning about the renormalization group and I am getting confused on some terminology. For the massless $\phi^4$ theory the Callan-Symanzik equation is: $$\big[ M \frac{\partial}{\partial M} + \...
CBBAM's user avatar
  • 3,350
0 votes
1 answer
38 views

Are there different ways of using the term 'energy scale'?

Are there a few different ways of using the term 'energy scale' that differ in their precise meanings? For instance, in the context of the chart provided, 'energy scales' denotes the magnitude of ...
qazwsx's user avatar
  • 989
1 vote
0 answers
41 views

What is the name of this pendulum? [closed]

What is the name of a pendulum with two parallel string hung vertical to a rod, and giving the rod an initial force would make it swing left and right, doing simple harmonic motion? What is the ...
user398341's user avatar
1 vote
0 answers
74 views

What is a name of a critical point?

Imagine a critical line separating two thermodynamic phases. There is a point on this line splitting the line into two pieces such that on one piece the transition between the two phases is 1st order, ...
AVR's user avatar
  • 11
0 votes
1 answer
89 views

Dirichlet’s Theorem and Solutions to Laplace Equation in Cartesian Coordinates

I have been reading Introduction to Electrodynamics - Griffiths about solving Laplace equation in cartesian coordinates, and in that book, I saw this statement: The functions $\sin(n\pi y/a)$ are ...
Sanjay's user avatar
  • 95
0 votes
1 answer
43 views

Definition of quenched data set/disoprder in the context of spin glass

I cannot come across a good definition of what "quenched" means in the context of spin glass problems. I see such use as "quenched connectivity", "quenched data set", &...
MsTais's user avatar
  • 1,184
1 vote
1 answer
389 views

Is this image on harmonics and overtones wrong?

I saw this image and believed this to be the definition of what the relationship between harmonics and overtones to be in strings, closed pipes and open pipes. That the $n^{th}$ harmonic = $n-1^{th}$ ...
John Hon's user avatar
  • 2,356
1 vote
1 answer
67 views

Why are $W$ and $Z$ bosons called 'intermediate' vector bosons?

What does the 'intermediate' part mean? Somehow, I thought an answer would be easy to come across, but I have yet to find one.
Kurt Hikes's user avatar
  • 4,509
0 votes
2 answers
46 views

Notation for intrinsic charge carrier

What exactly is $n_{\textrm{i}}$? It is said to be the intrinsic charge carrier, but for pure semiconductors, $n_{\textrm{h}} = n_{\textrm{e}} = n_{\textrm{i}}$, is $n_{\textrm{i}}$ not the sum of ...
ishigami's user avatar
1 vote
2 answers
136 views

What does $f(x)$ satisfies the given equation means?

In problem 2.1 part c of Introduction to Quantum Mechanics, 3rd ed. by Griffiths and Schroeter, they ask the reader to prove that if the potential is an even function of $x$, then if $\psi(x)$ ...
GedankenExperimentalist's user avatar
3 votes
2 answers
214 views

Difference between real operators and Hermitian operators in quantum mechanics

I'm reading some lecture notes on quantum mechanics, while describing the rigid rotor in bra-ket notation, the author mentions the parity operator $\hat{P}$ acting on kets as $\hat{P} \left \lvert m \...
Andrea's user avatar
  • 35
2 votes
2 answers
118 views

Are vacuum energy, zero point energy and vacuum fluctuations the same thing?

im confused about the relationship between these terms, my intuition tells me that vacuum energy and zero point energy are synonymous and that they are a consequence of vacuum fluctuations. But I ...
KleinMoretti's user avatar
0 votes
1 answer
176 views

Can we call numbers unidirectional vectors? [duplicate]

I have never thought so deeply about addition and subtraction. But today I noticed something. When adding or subtracting numbers, we actually apply the rules we use for vectors (for example, the ...
Bilgehan Yılmaz's user avatar
0 votes
0 answers
69 views

Name of Equation $Q = \Delta P / R$

A very fundamental equation in understanding fluid flow is $Q = \Delta P / R$. When the flow is through a cylindrical pipe of constant radius, $R=8\eta L/\pi r^4$ can be substituted to give Poiseuille'...
E Tam's user avatar
  • 145
5 votes
3 answers
630 views

Is Principle of Least Action a first principle? [closed]

It is on the basis of Principle of Least Action, that Lagrangian mechanics is built upon, and is responsible for light travelling in a straight line. Is its the classical equivalent of Schrodinger's ...
megamonster68's user avatar
1 vote
2 answers
93 views

Equations of motion in general relativity: Einstein field equations vs geodesic equation

It is said that the equations of motion of a theory are those whose solutions give the coordinates/trajectory of the system. I was wondering: which is the correct equation of motion in the theory of ...
Tomás's user avatar
  • 309
0 votes
1 answer
46 views

Terminology: any specific name for the amount of something in a given volume (at a given time)?

For quantities such as electric charge, amount of substance (or number of particles), and energy, the flux of the quantity is defined as the amount of quantity flowing through a predefined surface in ...
pglpm's user avatar
  • 3,753
0 votes
1 answer
36 views

Dielectrics terminology

I got confused while reading about dielectrics, so basically my question is: (a) what's the difference between a (homogenous and isotropic) dielectric and (linear) dielectric? Does the first imply the ...
tensorman666's user avatar
2 votes
2 answers
106 views

Constraint Equation and Equation of Motion

I was doing a question which was to find the number of generalized coordinates needed to describe a particle with the motion: $x(t)=2a\sin(\omega t) $ $y(t)=a\cos(2\omega t)$ So I solved it and found ...
Kutubkhan Bhatiya's user avatar
4 votes
4 answers
825 views

Why do we call the Riemann curvature tensor the curvature of spacetime rather than the curvature tensor of its tangent bundle?

I was studying the mathematical description of gauge theories (in terms of bundle, connection, curvature,...) and something bothers me in the terminology when I compare it with general relativity. In ...
eomp's user avatar
  • 123
-1 votes
1 answer
76 views

How is matter defined in physics? [duplicate]

I have heard matter defined as energy within a closed system and that any such closed system will have mass. Is this correct?
Gerry's user avatar
  • 151
2 votes
5 answers
501 views

What is the branch of physics that asks the question 'what was before the Big Bang'?

What is the branch of physics that asks the question 'what was before the Big Bang', assuming the Big Bang is truly what happened at the beginning of the universe? If there could be a better model ...
Bruce M's user avatar
  • 421
-1 votes
1 answer
148 views

What does instantaneous velocity mean? [duplicate]

What does instantaneous velocity mean? on google it says "Instantaneous means something happens very quickly, in a single moment. It's similar to the meaning of "instant", but most ...
Intensed's user avatar
1 vote
1 answer
128 views

Is there a difference between the spectral decomposition and the orthonormal decomposition of a matrix?

I was studying quantum information from Nielsen and Chuang's book and I got a little bit confused because sometimes they use the terms "spectral decomposition" and "orthonormal ...
Anis Younes's user avatar
0 votes
2 answers
71 views

Why is this called a `Harmonic Oscillator Chain'?

Consider the following general setup: Assume have a chain of atoms (of mass $m=1$) in one dimension interacting with their nearest neighbor through a interaction potential $U$, and which are in an ...
Monty's user avatar
  • 265
3 votes
2 answers
119 views

Unit in unit area

Pressure is defined as force per unit area. What is the meaning of unit and why is the term unit used with area?
Nandy's user avatar
  • 31
0 votes
3 answers
204 views

What is the correct term for $\nabla\phi$? Co-vector or 1-form or both?

In the olden days, $\nabla\phi$ was used to be called a covariant vector (Weinberg used this language in his book Gravitation & Cosmology). But this terminology is considered bad for several ...
Solidification's user avatar
0 votes
0 answers
9 views

What is the difference between granulatiion, mesogranulation, supergranulation and giant cells in sun's photosphere?

Help me understand the differences between granulation, mesogranulation, supergranulation, and giant cells and at what depth they are created.
Devesh Sharma's user avatar

1
2 3 4 5
46