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.
2,298 questions
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Why do physics textbooks use ≡ instead of := when defining terms? [closed]
I don't understand why physics textbooks like to use the ≡ symbol when defining quantities when it means equality.
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1answer
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Relationship between these two definitions of angular momentum
I learned in (1) that the angular momentum of a particle of mass $m$ at position $\mathbf{r}$ travelling at velocity $\mathbf{v}$ is an element $L\in\mathfrak{so}(3)^\ast$ defined by $L(X)=\mathbf{r}^...
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Total Pressure and Bernoulli's Equation
I looked at many definitions of total pressure which states that it is the sum of static pressure and dynamic pressure. However, the full form of Bernoulli's Equation includes the potential term ρgz ...
- 608
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Force-momentum definition [duplicate]
There is something I really do not understand about how we should define Force. When mass is constant then we can say that force is the rate of change of momentum and also it is mass times ...
2votes
2answers
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Why are free quantum fields said to be Gaussian?
This is perhaps a very elementary question, but it's something I was thinking about today and couldn't come up with a very good answer. The most general definition one can give for an object to be ...
- 4,500
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Are fields in particle physics some wave functions, that is amplitude of probability?
In particle physics, there are fields for fermions, typically labelled $\psi(x)$, and fields for scalar, typically labelled $\phi(x)$, which are functions of the space-time coordinate $x=(t, x, y, z)$....
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1answer
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Questions about the definition of Poisson bracket
Let's start with some preliminaries. Let $(M, \omega)$ be a symplectic manifold where $M=T^\ast X$ is $2d$-dimensional phase space for $d$-dimensional configuration space $X$, and $\omega:TM\times TM\...
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2answers
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Why are "hamiltonian operators" called "quantum theories"?
A large number of my professors say something along the line of. "Let's write down the theory". Then they write down the expression for a hamiltonian operator. I assume this might be related ...
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What is the weak anchoring mean and what is the no anchoring mean in nematic liquid crystal?
I am trying to do some simulation for the anchoring in nematic liquid crystal. Still, I am trying to understand what weak anchoring and no anchoring means in nematic liquid crystal first?
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Why is capacitance defined as $\frac{Q}V$ and not $\frac{V}Q?$
I was thinking about analogous situations for resistance, capacitance and inductance. For example, impedance, series and parallel combinations, damped mechanical vs electromagnetic oscillators. In an ...
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Is $k \cdot Z_{g,h}= Z_{g,khk^{-1}}$?
In 2D CFT, $k,g,h$ are elements of some symmetry group $G$. Given a partial trace $Z_{g,h}$, what's the action of $k$ on the partial trace $Z_{g,h}$? I heard that the group element $k$ act on the ...
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What exactly is decoherence?
In quantum mechanics particles that undergo decoherence (breaking of superposition to a definite state) is caused by its interaction with surrounding environment. In quantum mechanics Superposition is ...
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1answer
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Definition of the sphere at infinity
I am reading Manton-Sutcliffe's Topological Solitons, and they mention several times something they call the "sphere at infinity of $\mathbb{R}^d$, $\mathbb{S}^{d-1}_\infty$". However, I ...
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1answer
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How does one know that the entropy in the microcanonical ensemble is unique?
In my statistical mechanics course, we derived a form of entropy for the microcanonical ensemble. To do this, we imagined a system where there are two subsystems separated by a thermally conducting ...
- 1,987
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Taylor and Wheeler Definition of Inertial Frame
In Spacetime Pysyics, Taylor and Wheeler define an inertial frame as: A reference frame is said to be an “inertial” or “free-float” or “Lorentz” reference frame in a certain region of space and time ...
