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

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6
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3answers
71 views

What is the decay width and why is it given in energy units?

I'm reading Thomson, Modern Particle Physics, and in chapter 16 author says that the decay width of the Z boson is $\Gamma_Z =2.452 \pm 0.0023 \,\mathrm{GeV}$. He also says the total width of the ...
1
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0answers
13 views

Non-singlet and singlet flavor combination

What is non-singlet and singlet combination of quark flavors and why are they called in such a way? Does it transform in certain way under global flavor group transformation?
2
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2answers
66 views

The ability to squint and focus - what is it called and is it used in optics? [duplicate]

Most people that wear glasses or contacts can squint to reduce the blurriness of their vision. How can this be explained, and has it ever been used in optics to enhance the focus or clarity of an ...
6
votes
1answer
607 views

What is the difference between an isolated and a closed system?

What is the difference between difference between an isolated system and a closed system? Is it that for an isolated system, the system is free from external effects, but for closed system, the ...
1
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2answers
452 views

Correct terminology for combined kinematic and dynamic state

The kinematic state is defined as the position and orientation in space. The dynamic state is defined as the associated velocities. What is the correct terminology for the combined kinematic and ...
3
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2answers
122 views

Fluorescence and phosphorescence

Fluorescence is where UV light is absorbed then emits visible light right? Is it that you can only see it in the dark whereas phosphorescence is where UV light is absorbed and visible light is ...
1
vote
1answer
130 views

What is the difference between Fermi level and Fermi edge?

Just as in title: What is the difference between Fermi level and Fermi edge? My friend makes some research about XPS and he encountered this term. He knows what is Fermi level, but never heard about ...
3
votes
2answers
226 views

Quadrature in quantum optics

I am reading a chapter about Squeezed state, and came across this word, quadrature, which I have never seen before in the book. Here is the quote from that chapter. " A general class of minumum-...
2
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1answer
116 views

What does “downshear” mean?

I occasionally read descriptions such as "downshear of the vortex" in meteorological publications. What does this mean?
0
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1answer
31 views

Retrograde Watches [closed]

I am not a physicist and not familiar with physics that much.I have a watch which has Retrograde motion. I have read about what is ...
1
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1answer
106 views

What is the relationship between harmonic motion and the harmonics of a wave?

I learned about harmonic motion and harmonic oscillators a long time ago in physics, but I can't remember what the relationship between that and and the definition of harmonic in a wave. A harmonic ...
1
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4answers
68k views

What is the difference between phase difference and path difference?

I have learnt that path difference is the difference between the distance travelled by two waves meeting at a point. If that is path difference,then how will one know what is phase difference and how ...
0
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4answers
7k views

What is the difference between electromagnet and solenoid?

What is the difference between electromagnet and solenoid? Both these terms seem as the same thing to me. The only difference that I can find seems to be that an electromagnet contains a soft iron ...
2
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2answers
392 views

What is atmospheric stratification?

In the context of atmospheric stability, what are the meanings of stable or unstable stratification? What is stratification?
3
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1answer
540 views

What is meant by a “stiff” or “soft” equation of state (wrt neutron stars)?

I am currently trying to understand the history of the development of the equations of state and structure of neutron stars. In my textbook, I frequently encounter phrases such as "The ...
0
votes
1answer
66 views

Definition of a meson? [closed]

I am looking for a definition of a meson that does not include the quark model. After some research I have come across this definition: A meson is a particle that is (1) believed to be ...
6
votes
2answers
12k views

What is the difference between the words transparent and translucent?

Merriam Webster defines transparent as: Having the property of transmitting light without appreciable scattering so that bodies lying beyond are seen clearly. And translucent as: ...
4
votes
3answers
557 views

Locally flat coordinate and Locally inertial frame

I am having some doubts on myself regarding the above concepts in General Relativity. First, I want to point out how I understand them so far. A male observer follows a timelike worldline ($\gamma$) ...
10
votes
4answers
351 views

What makes an equation an 'equation of motion'?

Every now and then, I find myself reading papers/text talking about how this equation is a constraint but that equation is an equation of motion which satisfies this constraint. For example, in the ...
6
votes
5answers
9k views

What is a correct and simple definition of quantum physics?

Is it correct to define Quantum Physics as the study of Physics in sub-atomic scale? Does Quantum Physics studies something else other than sub-atomic phenomena?
5
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2answers
322 views

What's the difference between “evidence of a new particle” and “discovery of a new particle”?

Today’s exciting press release from Tevatron on the Higgs boson keeps its head cool and say that physicists saw a “hint” of the Higgs boson because the signal is barely above the two-sigma level. In ...
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3answers
753 views

Is net work and total work same?

According to my text book Total Work = Delta Kinetic Energy = KEf - KEi But then work is defined to be dot product of Force (vector) and Displacement (vector). Also to my knowledge work is ...
20
votes
3answers
4k views

Is Pauli-repulsion a “force” that is completely separate from the 4 fundamental forces?

You can have two electrons that experience each other's force by the exchange of photons (i.e. the electromagnetic force). Yet if you compress them really strongly, the electromagnetic interaction ...
2
votes
4answers
501 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 ...
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2answers
42 views

Gravity on other planets [closed]

Why we use the word"Earth' pull" while defining gravity when gravity also exist on other planets of solar system?
2
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2answers
272 views

What's the symbol for the antiparticle of the $\Delta^+$ baryon?

It can't be $\Delta^-$ since that is another particle also made up of quarks (not antiquarks). I can think of four possibilities: $\overline\Delta^+$ $\overline{\Delta^+}$ $\overline\Delta^-$ $\...
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0answers
26 views

Correct terminology or way to refer to the 2 “types” of ice sublimation

I'm trying to get the right terminology for various forms of phase change. I am familiar with the phase change / triple point diagram for water, and we have various terms for the transition of a ...
3
votes
2answers
99 views

The meaning of 'coupling'?

In quantum mechanics if two quantities $A$ and $B$ are said to be coupled what does this actually mean? I would guess that it means we have a term like $A\cdot B$ in the Hamiltonian but this is only ...
0
votes
1answer
113 views

The name of effect of liquid flow inducing flow to neighboring layers of liquid?

How do you call an effect, when liquid or gas stream is involving the neighboring layers of matter also move? Like on videos of rocket engines testing, when exhausting gas sucks an air and steam from ...
5
votes
1answer
1k 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 ...
7
votes
2answers
947 views

History of the names “Feynman-gauge” & “Landau-gauge”. How arised & how settled?

Edit: Use this PO.org question instead. Warning: Students, stay away from antiquities. The aim to learn is to survive. Hi. Today the nomenclatures Feynman gauge and Landau gauge seem established, ...
0
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3answers
56 views

Is the light emitted by a laser a 'beam' or a 'ray'? [closed]

In English, the light generated by a laser is almost always referred to in technical texts as a 'laser beam'. However, in French, Spanish, Portuguese and Italian, forms that correspond to laser beam ...
0
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1answer
51 views

What does it mean to say “internal symmetry”?

What does it mean to say "internal symmetry"? Let me try to express the way I see it, so you can have it as a starting point. There are spacetime symmetries, which are global since any Lorentz ...
3
votes
3answers
93 views

What is “normal” about normal frequencies and normal modes in coupled oscillations?

So, my question is what does the "normal" part mean when one talks about normal frequencies and normal modes in coupled oscillations. Does it have to do with the normal coordinates that one uses when ...
1
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1answer
170 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?
2
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0answers
32 views

What is the difference between selection efficiency and acceptance in high energy physics?

Often in papers the product of these two quantities is mentioned, but I'm not sure what exactly they mean separately. My guess would be that one of these is the fraction of the events that you are ...
3
votes
1answer
37 views

Can anyone please explain the meaning of vector resonances in the scenario of particle physics?

I was reading some material on Particle physics and I came across the sentence: pseudoscalar D and B meson states and the corresponding vector resonances D* and B*. What are vector resonances? ...
0
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0answers
53 views

Does the analogous saying: “matter is essentially 'condensed' energy” have any merit?

Einstein in his derivation of special relativity came upon the equivalence of energy and matter, and given the right circumstances, the relation can go either way - matter can become energy, and ...
1
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1answer
27 views

What do the authors mean by “closing operator”?

I'm reading a paper titled "Luminescence spectra of quantum dots in microcavities II Fermions" (link). In section III, the authors introduce so-called closing operators. I don't have enough background ...
2
votes
1answer
383 views

What was Feynman's famous formula?

In Welton(1983), Memories of Feynman, Welton mentions two formulas which he denotes as Feynman's Famous Formula (FFF) and FFF #2. Which famous formulas is he talking about? Is he maybe talking about ...
4
votes
4answers
3k views

Long/short-range interaction

A potential of the form $r^{-n}$ is often considered long-range, while one that decays exponentially is considered short-range. Is this characterization simply relative/conventional, or is there a ...
2
votes
1answer
51 views

Are hardness, strength and toughness of materials not the same thing in a way?

I had to look through several videos and re-read Wikipedia statements about these material properties several times before I could even begin to differentiate them. However, now that I have found out ...
1
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1answer
28 views

How are you the special points/critical points in the Brillouin Zone pronounced? [closed]

I know that this isn't exactly physics, but I don't know where to ask. http://en.wikipedia.org/wiki/Brillouin_zone#Cubic_lattice_system_CUB.281.29.2C_BCC.281.29.2C_FCC.281.29 The critical points/...
2
votes
1answer
42 views

What do the terms “offline” and “online” refer to in the field of high energy physics data analysis?

The title says it - I've encountered these terms several times but have never found an explanation anywhere. An example of use is this ATLAS note. If I may hazard a guess: Data rate is high at the ...
0
votes
1answer
127 views

Is 0.1 bar (hydrostatic pressure) equivalent to 0.1 bar vacuum pressure (absolute pressure)?

Suppose we would like to test the ability of an object to withstand the pressure under 1 meter of water. I would like to understand how to simulate this situation using vacuum. Is the 0.1 bar (for 1 ...
5
votes
1answer
214 views

Is there a specific name for the highest energy state in quantum mechanics?

In quantum mechanics, the lowest energy state is called the ground state. I am wondering if there is a name for the highest energy state? Should I call it the top state, or the ceiling state, or the ...
1
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3answers
100 views

What is meant by rest in rest-mass?

As far as I know only photons are considered to have no rest-mass. In common words when it doesn't move it 'disappears'. Electrons and quarks should have a rest-mass. But are they really at rest? ...
0
votes
1answer
41 views

Gruchestein Effect?

I overheard that name in a conversation, but not very clearly. I can't find anything on Google, probably because of my spelling is completely wrong. Does anybody knows about an effect with a similar ...
0
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0answers
30 views

What is the significance of Dirac ortho-normality? [duplicate]

What is the significance of Dirac ortho-normality? We know for momentum eigenfunction $f(p,x)$ for eigenvalue $p$ , $$\langle f(p',x) | f(p,x)\rangle~=~ \delta(p - p') $$ I am not clear why it is ...
1
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2answers
116 views

Do the matrices $S^{\mu\nu} = \frac{1}{4}[\gamma^\mu, \gamma^\nu]$ have a name?

Do the matrices $S^{\mu\nu}$ defined by $$ S^{\mu\nu} = \frac{1}{4}[\gamma^\mu, \gamma^\nu] $$ have a name ($\gamma^\mu$ are the gamma matrices)? They feel very important to me since they form a ...