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

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3answers
105 views

Meaning of invariable

Invariable means which is not variable i.e. can't be changed. Recently I have seen a sentence when reading a chapter based on measurement: The accepted standards must be accessible to those who ...
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2answers
237 views

Conversion of ideal gas to real gas via $Z$ compression factor

The ideal gas equation $PV=nRT$ can be converted into real gas equation by compression factor $Z$ i.e $PV=Z~ nRT)$. My question is what is $Z$ and how does it arise? Is $PV/nRT$ a compression ratio of ...
3
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1answer
116 views

How to determine the order of indications of a clock?

Given the description of a clock $\mathcal A$, as (1) a set $A$ of all (more than 2) distinct indications of this clock, in no particular order (where the individual indications contained in set ...
2
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1answer
46 views

Hot Big Bang vs. Big Bang

This should hopefully be a quick one. Is there any difference between the Big Bang Theory and the Hot Big Bang Theory? Around Cambridge I hear everyone using "Hot Big Bang Theory", for example ther ...
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0answers
195 views

Physical interpretation: weighted eigenvalues of the Laplacian with a potential

I'm a mathematician with only the basic knowledge of Physics, so my question may be trivial: in this case, mercy me. :-) Let $\Omega \subseteq \mathbb{R}^N$ be a domain and let $V,m:\Omega \to ...
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0answers
73 views

What does the term 'a uniform RVB spin-liquid state' mean?

I encountered this term a uniform RVB spin-liquid state in some articles, for example, see the paragraph under Eq.(29) on page 9 in this paper. What does the word 'uniform ' mean? Simply from the ...
3
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0answers
377 views

Difference between inorganic and organic semiconductors: electronic structure or configuration, or?

Organic semiconductors differ from inorganic semiconductors. In organic semiconductors the molecules are held together by weak van der Waals interactions and in inorganic semiconductors by covalent ...
2
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0answers
30 views

Since “coordinate time” has a very specific meaning, how to call more general parametrizations?

Recently I've learned that "coordinate time" assigned to a particular time-like spacetime path is not only required (1) to be monotonous and continuous and even differentiable wrt. the "proper time" ...
2
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0answers
20 views

What does unfolding of attractor mean?

What does unfolding of attractor mean? Effect of time scales on the unfolding of neural attractors paper talks about Takens embedding theorum. It says that the embedding dimension should be large ...
2
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0answers
70 views

Why is the projective symmetry group (PSG) called projective?

As discussed by Prof.Wen in the context of the quantum orders of spin liquids, PSG is defined as all the transformations that leave the mean-field ansatz invariant, IGG is the so-called invariant ...
2
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0answers
26 views

What is Jacobian about the “Jacobian Edge” in $E_\mathrm{T}$ distributions?

Particle physicists often talk of a "Jacobian Edge" in distributions, i.e. when looking at the $E_\mathrm{T}$ distribution of $W \to e \nu$ decays at rest. How is this related to the Jacobian ...
2
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0answers
51 views

What is the 1/2 spin analog of the graviton called?

In some supergravities you have the gravition, gravitino, graviphoton and graviscalar. Each is analogous to each other in only sharing gravitational properties and nothing else. They differ by spin ...
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0answers
105 views

How to name different approaches to relativistic quantum theory

In the introductory chapter of the QFT book by Mark Srednicki the author notes that [p. 26] So now we have two different approaches to relativistic quantum theory [...] Which [one of those two] we ...
2
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0answers
50 views

What name would you give to the method of approximating an arbitrary magnet with many smaller dipoles?

Let's say I had an arbitrarily shaped permanent magnet, with total magnetic moment $M_{0}$. Ways to calculate the magnetic field of this magnet include an analytic solution (if one exists), as well ...
2
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0answers
486 views

de Sitter and anti de Sitter metric

Is the following correct for the distance $d$ from the origin $(0,0)$ to point $(t,x)$ in the 2-dimensional de-Sitter and anti de-Sitter spaces? Here, $t$ is time and the distance may be called the ...
1
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0answers
154 views

Morphisms between chiral CFTs

This is a question about terminology. Given two vertex algebras $V_1$ and $V_2$ (= chiral CFTs), there are two kinds of maps $V_1\to V_2$ that one might want to consider. 1) Morphisms of VOAs that ...
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0answers
52 views

What is the definition of a charge-neutral operator?

What is the definition of a charge-neutral operator? I guess it means something like: it is invariant under charge conjugation. It that correct?
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0answers
21 views

What is the mean ionospheric height?

I am reading some articles about the ionosphere and I am a little bit confused about the terms mean ionospheric height and effective height of the ionosphere. Are these the same thing? I would ...
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0answers
46 views

Do two synchronous clocks have simultaneous indications?

Considering two clocks, $C$ and $D$, which were at rest to each other throughout a sufficiently extended trial, and given their time parametrizations $t_C : {\text{ ordered set of}}C{\text{'s ...
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0answers
44 views

Why are polymer representations called “polymer representations”?

Why are polymer representations called "polymer representations"? Polymer representations deal with non-continuous unitary representations of groups acting on nonseparable Hilbert spaces (see e.g. ...
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0answers
58 views

Trying to speak correctly of spacetime intervals and how to compare them

Is it correct to speak of "magnitude of a spacetime interval"? For instance, considering a pair of (distinct) events, $A$ and $B$, which are lightlike separated, is it correct to say that "the ...
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0answers
341 views

How is the term “Born level” usually defined?

How is the term "Born level" usually defined, e.g. in talking about the $pp\to Z/\gamma^*\to e^+e^-$ cross section at Born level?
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0answers
407 views

What is the relationship between Luminosity, Intensity, and Flux?

I am always confused by the terminology: In high energy particle scattering, and in particular, in the context of collider physics, what is the relationship between luminosity, intensity and flux? ...
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0answers
92 views

Is putting a charged balloon up to a neutral wall polarization AND temporary induction, or just polarization?

Is putting a balloon that is charged up against a wall and having it stick polarization AND charging by temporary induction, or just polarization?
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0answers
441 views

What is a boundary condition for capacitors/dielectrics?

I am extremely confused about what boundary conditions are. One minute ago I was solving easy capacitor questions and the next minute I am being asked boundary condition questions and there is no such ...
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0answers
52 views

Why is the $SO(4)$ symmetry of the Hydrogen atom called dynamical?

Why dynamical? My previous quantum mechanics teacher could not answer it.
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0answers
26 views

What are torque parameters?

Torque is just the turning force on an object, i.e the force multiplied by the perpendicular distance from the force to the pivot. But when torque parameters are mentioned in mechanical engineering ...
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0answers
51 views

Actions at a distance vs. contact interaction

The ancestors could not imagine an action at a distance (in German: "Fernwirkung"). Today physicists don't take serious its opposite anymore (in German: "Kontaktwechselwirkung"). So my first question ...
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0answers
46 views

Difference between RPA and generalized RPA

The random phase approximation (RPA) is an approximation method in condensed matter physics and in nuclear physics. What is the difference between RPA and generalized RPA?
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0answers
21 views

What is “thermal undulation” in the context of lipid bilayers?

What is thermal undulation in the context of lipid bilayers? Is it another word for "thermal fluctuation"?
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0answers
25 views

Is there a generic term for orbital groups such as $e_g$ and $t_{2g}$?

I am looking for a generic term for sets of atomic orbitals (viz. spherical harmonics) which are grouped by crystal symmetry. The most familiar examples would be $e_g$ and $t_{2g}$ (in cubic ...
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0answers
25 views

Origin of the names for the decay chains

Is there any reason for the names of the decay chains? As shown in this chart (larger version here): only the Thorium chain starts on an isotope of the element it takes its name from, and it can ...
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0answers
34 views

Have there been more distinctive names suggested for neutrino mass states $\nu_1, \nu_2, \nu_3$?

The different mass states of neutrinos are generally named $\nu_1, \nu_2, \nu_3$. By comparison, the names of quark mass states (up, ...
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0answers
83 views

What does “define analytically” mean?

I'm trying to do my homework in physics but here I have found something that I am not understanding. It says: Define analytically the terms that should stationary flow accomplish. I know that ...
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0answers
83 views

Magnitude of a photon?

I encountered the following sentence in my textbook, which I don't quite understand, and after an unfruitful google search, I still can't figure out what they mean by magnitude in this context: ...
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0answers
49 views

What is to be considered a “body” in physics?

Well, the question says it all; is there a definition of body in physics? What is to be considered a physical object and what it cannot?
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0answers
169 views

What is the electric field part of an EM wave? Radiation field or the induction field?

Look at this image: I wonder if the electric field is from the induction field from a vibrating electron or the radiation field? If it is from the radiation field, as I suppose, than can someone ...