# Questions tagged [terminology]

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

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### What does “channel” mean in the context of QCD?

I am familiar with the common use for "channel" in terms of particle physics (like Mandelstam variables). What confuses me is how it's used in the following paper on QCD: C. A. Dominguez, &...
133 views

### Is there a special name for thermodynamic process during which no work is performed?

Let $W$ denote the work done on a system during a thermodynamic process. Is there a commonly-accepted, dedicated term for a process during which $W=0$?
377 views

### What is the difference between “field equations” and “equations of motion”?

I come across the terms "equations of motion" and "field equations" all the time, but what is the difference? For example, general relativity is described in terms of the Einstein ...
31k views

### What is the difference between electric potential, potential difference (PD), voltage and electromotive force (EMF)?

This is a confused part ever since I started learning electricity. What is the difference between electric potential, potential difference (PD), voltage and electromotive force (EMF)? All of them have ...
45 views

### Why can the word “fusion” mean either “combining” or “breaking/melting” in different contexts? [migrated]

The word "fusion" is at times confusing because in a way it has two opposite meanings: Combining things together, for example "nuclear fusion". Melting/breaking things, for ...
196 views

### $B$-meson naming convention

An unbarred $B$-meson contains $\bar{b}$ (an anti-bottom quark), whereas a barred $\bar{B}$-meson contains $b$ (a bottom quark). What is the historical reason for this hellish naming convention?
13 views

### “Directionally” translational variance of a function(al)?

Let $f:\mathbb R^3\to\mathbb R$. We define that $f$ is transnational variance if: For any $a\in\mathbb R^3$, $f(x)=f(y) \Leftrightarrow f(x+a)=f(y+a)$. However, if $a$ is limited to be some specific ...
62 views

### What does “continuous spacetime” mean?

I often encounter discussions, such as seen here, about whether spacetime is discrete or continuous. However, I am only familiar with continuity as being a property of functions. I saw this question ...
70k views

### Why and how does negative velocity exist?

Why and how does negative velocity exist? I have read on the internet about negative velocity but I still don't understand how it can even exist since time is positive and so is length. By doing some ...
1k views

### What is “A” in AGeV?

AGeV means GeV per nucleon. But why A letter is used for such a short cut? Why not NGeV, for example?
22 views

### How to convert GeV to AGeV? [duplicate]

The beam energy is sometimes in AGeV in collider papers. I'm stuck on how to convert AGeV to GeV.
2k 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". ...
134 views

### Transmission coefficient and transmission probability

Are transmission coefficient and transmission probability the same terms? If not, could you please explain how they are related to each other?
584 views

### What is the definition of “Complexity” in physics? Is it quantifiable?

I don't know much about the discipline of "Complex systems studies" but I know in the field of "Statistical mechanics" there is much talk about the "Complexity of the system&...
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### Whatās the difference between FoV and IFoV?

I read that radio telescopes have āhuge fields of view (FoV)ā, but are unable to precisely localized objects due to their āsmall instantaneous field of view (IFoV)ā. Apparently, somehow the size of ...
31 views

### What is the difference between toughness and hardness? [duplicate]

What is the difference between toughness and hardness? I came to know about some materials that have low toughness but high hardness such as ceramic tiles and glass. I want to know if it is true that ...
49 views

### Is there a “non-linear limit” of the Dirac equation?

I'm just going through old protocols of oral exams students wrote up. One student writes that he was supposed to derive the "non-linear limit" of the Dirac equation during the exam. Is there ...
969 views

### Variables in calculation of drag coefficient

Okay, so I looked up drag force equation, and I found that the equation involved the drag coefficient. Then I looked up the drag coefficient, and the equation for it involved the drag force. ...
2k views

### What is an event in Special Relativity?

Lorentz transformations help us transform coordinates of one frame to that of another. For example, let the coordinates of an event in an inertial frame $S$ be $(x, t)$, then the coordinates in frame ...
62 views

### How come random is a wave? [closed]

In Schrodinger's theory of the atom, an electron does not move on a circular path. Its motion is in 3D and its random. It could be anywhere in space. How come they named it to wave form? If it's ...
48 views

### What's the meaning of $\Delta E-W_{nc}=0$?

Suppose a system of particles is subject to internal forces, some of which are conservative and some of which are non-conservative. Let $\Delta E$ be the change in mechanical energy of the system as ...
384 views

### Is a bending wave transverse or longitudinal?

A bending wave in a metal bar or string is simply called a transverse wave because the macroscopic oscillation is transverse. However, paradoxically, in a frame co-moving with the atoms, the atoms are ...
65 views

### What does the term 'high voltage' really mean?

This might be a dumb question but i am not so familiar with the word voltage: What does the textbooks really mean when they say high voltage?. Does that mean: There are more charges so more voltage, ...