Questions tagged [definition]
The definition tag is used in situations where the question is either about how some term or concept is defined or where the validity of an answer depends on a subtle definition of some term or concept used in the question.
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Mathematical definition of Bogomol'nyi–Prasad–Sommerfield (BPS) states
What is the mathematical definition of Bogomol'nyi–Prasad–Sommerfield (BPS) states, independent of any specific physical theory.
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Name for celestial "Prime Meridian"?
Is there name for the line that goes from celestial pole to pole at RA 0 degrees 0 minutes 0 seconds? On Earth we would call it the Prime Meridian. Is it called the "Celestial Meridian"?
forestplay
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What is the difference between electric potential, electrostatic 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, electrostatic potential, potential difference (PD), voltage and electromotive ...
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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 ...
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What distinguishes a moon from orbiting space debris? Or in other words, when is a satellite "too small" to be a moon?
The Wikipedia article on Natural Satellites doesn't really give an adequate distinction as to what distinguishes a moon from other orbiting bodies. What I am looking for is a classification that ...
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History of interpretation of Newton's first law
Nowadays it seems to be popular among physics educators to present Newton's first law as a definition of inertial frames and/or a statement that such frames exist. This is clearly a modern overlay. ...
user4552
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Can temperature be defined as propensity to transmit thermal energy?
I was recently surprised to learn that defining temperature isn't easy. For a long time, it was defined operationally: how much does a thermometer expand. Also surprising, temperature isn't a ...
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Vesta dwarf planet status
Now that we have close-up photos of Vesta, which the IAU had previously said was a candidate dwarf planet, when is the IAU going to decide the issue? Personally, Vesta doesn't look round enough to me.
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What is an inverse femto barn?
I came across the use of the unit barn and inverse barn while reading about the operation of LHC. What is an inverse femtobarn? What does it tell about the experiment being described?
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What examples are there of fuzzy concepts in astronomy?
What examples are there of fuzzy concepts in astronomy? In particular, how fuzzy are the boundaries between different types of stars?
As an example of a fuzzy concept I'm thinking of the planet/brown ...
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Two planets in same orbit - not planets?
Let us pretend for a moment that there are two identical planets that are exactly opposite their star from each other and are the same distance from said star. (This would make them, at all times, ...
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What is the difference between "Christoffel symbols" and "affine connection"
What is the difference between the "affine connection" (S. Weinberg, Cosmology) and "Christoffel symbols?"
Cor
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What is an asterism compared to a constellation?
I'm doing an astronomy exam tomorrow and in the practice paper it asks for the difference between constellation and asterism. It seems asterism is a group of recognizable stars; however I thought that ...
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What is the current status of Pluto?
Pluto has been designated a planet in our solar system for years (ever since it was discovered in the last century), but in 2006 it was demoted.
What caused this decision? And is there a chance that ...
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What is a coherent state?
In quantum mechanics, what exactly is a coherent state, and how does it differ from other states?
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Are inductance and self-inductance synonyms?
Wikipedia mentions that the word self in the word "self-inductance" is to differentiate it from "mutual inductance". But it does not state whether the two things are the same thing. So do the both ...
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Why is the speed of light defined as 299792458 m/s?
Why is the speed of light defined as $299792458$ $m/s$? Why did they choose that number and no other number?
Or phrased differently:
Why is a metre $1/299792458$ of the distance light travels in a ...
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What is the difference between implicit, explicit, and total time dependence, e.g. $\frac{\partial \rho}{\partial t}$ and $\frac{d \rho} {dt}$?
What is the difference between implicit, explicit, and total time dependence, e.g. $\frac{\partial \rho}{\partial t}$ and $\frac{d \rho} {dt}$?
I know one is a partial derivative and the other is a ...
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What exactly is $F$ in $W = \int_{a}^{b} F dx$?
I am trying to teach myself some basic physics, here is something I do not really understand about the definition of work:
When moving from $a$ to $b$ (in one dimension), the work done is defined to ...
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what is meant by "crossover phenomena"?
In many articles I read the term "crossover phenomena" and a lot of methodology discussed according to it, with little or no description about what is meant by it. Sometimes there is a connection to ...
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What is the definition of how to count degrees of freedom?
This question resulted, rather as by-product, the discussion on how to count degrees of freedom (DOF). I extend that question here:
Are necessary1 derivatives such as velocities counted as individual ...
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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 ...
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What's the difference between the five masses: inertial mass, gravitational mass, rest mass, invariant mass and relativistic mass?
I have learned in my physics classes about five different types of masses and I am confused about the differences between them.
What's the difference between the five masses:
inertial mass,
...
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Definitions and usage of Covariant, Form-invariant & Invariant?
Just wondering about the definitions and usage of these three terms.
To my understanding so far, "covariant" and "form-invariant" are used when referring to physical laws, and these words are ...
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Simple explanation of quantum mechanics [closed]
Can you please describe quantum mechanics in simple words? When ever I read this word (quantum computers, quantum mechanics, quantum physics, quantum gravity etc) I feel like fantasy, myth and ...
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Are we crystals?
Can we say that we are crystals because just like crystals we are made up of very small unit (cell) making up almost the same shape (our body) everywhere.
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What is a D-brane?
I know that in string theory, D-branes are objects on which open strings are attached with Dirichlet boundary conditions. But what exactly is a brane? Are they equally fundamental objects like string? ...
user1355
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What does it mean for a Hamiltonian or system to be gapped or gapless?
I've read some papers recently that talk about gapped Hamiltonians or gapless systems, but what does it mean?
Edit: Is an XX spin chain in a magnetic field gapped? Why or why not?
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What is the definition of physically meaningful?
I asked a question recently where I wanted to know whether it was physically meaningful to talk about the arrow of time in other universes.
Although many people apparently have an intuitive notion of ...
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What is quantum entanglement? [closed]
What is quantum entanglement?
Please be pedagogical.
Edit: I have updated my background under my profile.
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What Is Energy? Where did it come from?
The simplistic undergrad explanation aside, I've never really understood what energy really is. I've been told that it's something when converted from one kind of something to another kind, or does ...
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Potential functions
Can someone please explain what a potential is? Example. velocity potential in ideal flows, acoustic potential (gradient of which gives the particle velocity in a sound wave).
Whenever I see potential ...
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Why are quark types known as flavors?
There are six types of quarks, known as flavors.
Why where these types called flavors?
Why do the flavors have such odd names (up, down, charm, strange, top, and bottom)?
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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 ...
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What is sound and how is it produced?
I've been using the term "sound" all my life, but I really have no clue as to what sound exactly is or how it is created. What is sound? How is it produced? Can it be measured?
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