Use this for questions relating to the proper use of physics terminology or nomenclature.
1
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1answer
98 views
Reality constraint
What is the "definition" of a reality constraint and why is it called that way?
(I mean how it is used for example in quantum field theory and string theory)
2
votes
2answers
2k views
What's the difference between constitutive laws and governing equations?
I'm studying about the finite element method in a class but I don't come from a civil engineering background. Anyways, it hasn't been made clear to me what the difference between constitutive laws and ...
1
vote
1answer
64 views
Where can I find the equations for “quasi” elastic collisions?
Yes, you all talk about neutrinos and spins, but I came out with this basic s**t :D
All of us learnt the basic equations of collisions, elastic (everything bounces and energy remains the same), or ...
2
votes
3answers
2k views
Torque vs Moment
I was wondering, why in Newtonian physics torque is called "torque" while in static mechanics they call it "moment"?
I prefer by far the term "torque", for not only it sounds strong, but also ...
2
votes
4answers
606 views
Work done by the Magnetic Force
The magnetic part of the Lorentz force acts perpendicular to the charge's velocity, and consequently does zero work on it. Can we extrapolate this statement to say that such a nature of the force ...
3
votes
1answer
506 views
What phrases describe collisions with coefficients of restitution less than zero or greater than one?
The coefficient of restitution describes the elasticity of a collision:
1 = perfectly elastic, kinetic energy is conserved
0 = perfectly inelastic, the objects move at the same speed post impact
...
2
votes
4answers
896 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?
This may be a very stupid question ...
4
votes
2answers
433 views
The definition of “frequency” in different contexts
I have been doing some research on all kinds of sound-related topics lately and have been a bit confused by the different uses of the term "frequency". Of course, the most general meaning of frequency ...
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8answers
3k views
What is the difference between electric potential, voltage and electromotive force?
This is a confused part ever since I started learning electricity. What is the difference between voltage and electromotive force (emf)? Both of them have the same SI unit, right? I would appreciate ...
3
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4answers
492 views
Basic question concerning pure energy
Inside the core of a star thermonuclear fusion reaction fuses hydrogen atom into helium releasing massive heat/light and energy.When a blackhole eats up enough stars and gases it devours itself by ...
0
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1answer
113 views
Name for phasor model of light
I'm looking for the name of the model of light "exploring" every path to a given point, and reaching that point with a probability proportional to the square of the resultant phasor's amplitude. (Yes, ...
2
votes
1answer
110 views
What does “single inclusive” mean exactly?
I thought I knew what single inclusive scattering was, but today when I went to look up a definition to check my memory, I couldn't find one. A Google search yielded no shortage of papers that use the ...
1
vote
2answers
506 views
What do physicists mean when they say “speed of light”?
Does it make sense to say, "The speed of light varies?" Some may say right off the bat yes, it changes as a wave passes through a different medium. However, I'd like to say no, because when I hear ...
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vote
2answers
3k views
What is the difference between angular speed and tangential speed in a circular motion?
I was looking a long time for the way the equations of this two speeds are obtained, and i found pretty much nothing important, so can someone explain how are those obtained, and which is the ...
1
vote
3answers
546 views
Meaning of dimension
I was wondering what dimension can mean in physics?
I know it can mean the dimension of the space and time.
But there is dimensional analysis. How is this dimension related to and different from the ...
6
votes
1answer
1k views
Eigenfunctions v.s. eigenstates
Is there a difference between "eigenfunction" and "eigenstate"? They seem to be used interchangeably in texts, which is confusing. My guess is that an "eigenfunction" has an explicit ...
5
votes
1answer
197 views
Nomenclature of radial solutions to the Schrodinger Equation
For the free particle with quantum number $l=0$, the regular solution to the radial Schrodinger equation is $R_0 (\rho)=\frac{\sin{\rho}}{\rho}$ while the irregular solution is $R_0 ...
3
votes
2answers
482 views
What is the specific meaning of “Fourier frequency” (as opposed to simply “frequency”)?
I've noticed that many journal articles (in optics) use the phrase "Fourier frequency" to describe, well, the frequency of something.
Google scholar search for "Fourier frequency".
Example:
...
2
votes
3answers
447 views
If an atom is fully ionized by removing all electrons, is it still an atom?
This is a question about terminology. To me, it's clear that the nucleus of an atom is still an atom. But a comment by Willie Wong at Is nature symmetric between particles and antiparticles? raises ...
6
votes
3answers
66 views
Do days and months on the Moon have names?
On Earth we have various calendars, for example,
Days: Monday, Tuesday, Wednesday, etc., etc.
Months: January, February, March
Does the Moon have names for its "daily" rotations, etc.?
It sounds ...
5
votes
3answers
3k views
What is the official difference between a planet and a dwarf planet?
I'm trying to understand how objects are classified as planets, moons, or dwarf planets. Can someone please explain the differences between them? I'm really curious about why Pluto is a dwarf planet, ...
15
votes
2answers
112 views
What is a “Trojan Moon”?
Today I read an article about Saturn's moon Helene, and it was described as a "Trojan Moon" but no further explanation was given. It was difficult to even get any context about the term from the ...
11
votes
4answers
1k views
Does Earth have a code name?
Everything we discover in the sky get eventually a code name, like NGC 7293, Simeis 147, etc.
Does Earth/Moon have a code name too? Or it is just Earth/Moon, etc.?
4
votes
3answers
474 views
Nomenclature: Yang-Mills theory vs Gauge theory
If you're writing about a theory with Yang-Mills/Gauge fields for an arbitrary reductive gauge group coupled to arbitrary matter fields in some representation,
is it best to call it a Yang-Mills ...
0
votes
1answer
249 views
What's the difference between “measurement method” and “measurement procedure”? [closed]
The ISO VIM defines them as:
measurement method:
generic description of a logical organization of operations used in a
measurement.
measurement procedure: detailed description of a ...
5
votes
2answers
188 views
Nomenclature of hadronic resonances
I have the Particles Physics Booklet and I noticed that the resonances that decay into a nucleon and pion are indicated by an abbreviation. For example $P_{33}$ is associated to the $\Delta (1232)$ ...
0
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1answer
350 views
Metrology: What is precision for a measurement? [closed]
Is precision a "quality" of a measurement?
Is there a better (accepted by the literature) word?
3
votes
1answer
377 views
What's a better phrase than “speed of light” for the universal spacetime speed constant? [closed]
The phrase "speed of light" is commonly used for the constant c =3E8 m/s, a feature that's "hardcoded" into the structure of spacetime. All massless waves and particles move at this speed, and it's a ...
1
vote
3answers
5k views
What is the difference between a moment and a couple?
In mechanical engineering, the torque due to a couple is given by $\tau = P\times d$, where $\tau$ is the resulting couple, $P~$ is one of the force vectors in the couple and $d$ is the arm of the ...
7
votes
8answers
971 views
What is the name of the principle saying it is meaningless to talk/ask questions that can not be measured/tested?
Watching quantum mechanics lectures and it was mentioned that it is pointless/meaningless to try to talk/question things that can not be tested/measured.
Is this a principle? And if so what is it's ...
9
votes
3answers
2k views
What's the difference between an entangled state, a superposed state and a cat state?
1) Can a state be entangled without also being a superposition? (Please give an example.)
2) Can a state be a superposition without being entangled? (Again, an example please.)
3) And what about ...
4
votes
1answer
574 views
Mnemonics for remembering physical data
Anyone have good mnemonics for remembering standard packets of data in physics?
Any field within physics would be welcomed. Examples of such "packets":
data in the standard model of particle ...
1
vote
1answer
3k views
Is there a name for the derivative of current with respect to time, or the second derivative of charge with respect to time?
This measurement comes up a lot in my E&M class, in regards to inductance and inductors.
Is there really no conventional term for this?
If not, is there some historical reason for this omission?
...
9
votes
2answers
3k views
What's the difference between inclusive and exclusive decays?
For example, why is the semileptonic $B$ decay $B \to X\ell\nu$ inclusive?
I can't find any definition of these frequently used terms, strange.
13
votes
7answers
1k views
What is a general definition of impedance?
Impedance is a concept that shows up in any area of physics concerning waves. In transmission lines, impedance is the ratio of voltage to current. In optics, index of refraction plays a role similar ...
