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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What is the difference between an ultraviolet limit and ultraviolet stability?
One common way to analyze a quantum field theory is to regularize it by introducing an ultraviolet cutoff. After perhaps renormalizing the theory, one would hope that you can remove the cutoff by ...
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How do we decide whether a vibration of a solid object is longitudinal or transverse, when the object is not a 1D rod or 1D string?
In my understanding, a vertical needle that moves straight up and down should be a longitudinal vibration, because according to textbooks' definition, the motion is along the needle’s rest axis.
But ...
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When does a rocky planet stop being a rocky planet?
I am not aware of any well defined line between a rocky planet and a gas giant/ice giant.
There doesn’t seem to be a firm boundary and it seems like a very fuzzy concept.
This works okay for the solar ...
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What is the “Mourou” limit in this context?
I’ve seen this diagram
and I’m curious about what the Mourou limit means there.
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Why do “points” in phase space correspond to possible physical states of a system, rather than “lines”?
Why aren't “lines” the physical states of system, instead of “points”? In a simple harmonic oscillator, the motion of particles changes back and forth between kinetic and potential energy, but it ...
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Thermodynamic definition of temperature [duplicate]
Question:
In thermodynamics, temperature is defined by
$$
\frac{1}{T} = \left( \frac{\partial S}{\partial E} \right)_{V, N}.
$$
This definition is mathematically consistent and reproduces the expected ...
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Fixed vs free ends in 1D standing waves
In introductory physics courses one often discusses standing waves on a string with two fixed ends. A standard experimental demonstration of this is given here.
My problem is that in such a ...
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Definition of stationary field in a curved spacetime
I am wondering what the definition of a stationary (scalar) field in a curved spacetime is?
Alternative 1: Let $\phi$ be a (scalar) field in a curved spacetime with coordinates $(t,x^1,x^2,x^3)$. ...
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Why can a change in randomness (entropy) be mathematically expressed as $\frac{Q_{rev}}{T}$?
The change in entropy of a system resulting from a thermodynamic process can be calculated as:
$$\Delta S = \frac{Q_{rev}}{T}$$
where $Q_{rev}$ is the heat evolved/absorbed in the process had it ...
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Definition of Black Hole
Wald and other literature defines the definition of Black Hole as
$$B=M-J^{-}(\mathscr{I}^+)$$
where M is spacetime, $\mathscr{I}^+$ is future null infinity and $J^-$ is causal past.
The idea is to ...
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If scalar is a magnitude, vector is a magnitude and direction, then what tensor is about? [duplicate]
Well, from precisely mathematicians, i am not sure if scalar and vector can be view as i said. But i notice that
Scalar describes as 1 aspect quantity, whether it is magnitude or amount of something.
...
user222803
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What does it mean for work to be done ON a system?
I have been reading different literature on thermodynamics for a course at university, and of course, the idea of work being done ON a system is very central. What is rather seldom explained, perhaps ...
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(QM) What exactly is inner product in Dirac notation?
I'm a new learner of quantum mechanics and I have some problems about inner product in Dirac notation.
By Dirac notation, a function $f(x)$ is represented by |$f$$>$ .
According to my knowledge, $&...
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When calculating pressure in fluids, will neglecting the tangential component $F_\parallel$ ever lead to significant inaccuracies?
In many school and university textbooks, pressure $p$ is commonly defined as a scalar:
\begin{equation}
p=\frac{F_\perp}{A},
\end{equation}
where $F_\perp$ is the normal component of the force with ...
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How are these characterizations of reversible processes equivalent? + related question
I am taking a course in classical thermodynamics and something which confuses me a lot is the idea of a reversible process. In our lectures, our professor defined it the following way:
Definition
A ...
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