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Is it possible to 'twist' a magnetic field? I am not referring to the electrical field but the actual magnetic field.
In OAM (orbital angular momentum) we can twist light waves and sound waves however can this be done for a magnetic field?
I've seen research on curving antennas to twist electromagnetic waves and it wor... |
Can we obtain the worldsheet CFT describing string theory as a fixed point of some renormalization group flow (although I assume it leads breaking of diffeomorphism)? In other words, any irrelevant deformation of the worldsheet CFT have been discussed or known?
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I am trying to obtain the transformed wavefunction $\psi$ under gauge transformation in the presence of the E-M field. So Schrödinger's equation is (in the units $c=1$ and $\hbar$ = 1)
$$i\frac{d\psi}{dt} = H\psi \text{,} \qquad \text{where } H=\frac{(p -qA)^2}{2m} + q\phi.$$
consider the gauge transformation
$$A\rig... |
For a lab report, I am measuring the voltage across a 300 mH coil when connected to an alternating current supply at different frequencies. From this, I want to graph the inductive reactance (calculated using V/I) of the coil against frequency.
However, graphing it reveals a linear correlation that intercepts significa... |
So i did one physics problem where I should find apparent depth of 3m deep pool(index between liquid in pool and air is (√7)/2) and we are looking at pool from 30° angle.
I go to our favorite friend Google for help. I find some equation similar to (real depth)/(apparent depth)=refractive index. This doesn't work.
I got... |
I have a very simple question, but strangely I cannot find any answer on the internet; maybe the answer is too simple that I don't notice. I go straight to the point: if I define a Lagrangian from a Lagrangian density, and so from a definite integral in the coordinate space, how there can be an explicit coordinate depe... |
I am currently studying Maxwell's equations. Out of interest, I was reading the introduction to the textbook The Quantum Theory of Light, third edition, by Louden. When discussing the photon, the author says the following:
The idea of the photon is most easily expressed for an electromagnetic field confined inside a c... |
I actually have two different sub-questions, both based on the understanding of the quadratic term of the lagrangian, so the answer is probably linked. I will use the example of the linear-$\sigma$ model because it's the one I'm more comfortable with, so
$$\mathcal{L}=\frac{1}{2}\sum\partial^\mu\phi_i\partial_\mu\phi_i... |
In several introductory statistical mechanics books/notes I have seen, the idea of equilibrium is introduced by asserting the existence of a constraint equation between the properties of two systems, A and B, usually stated as
$$f_{AB}(A_1,A_2,...;C_1,C_2,...)=0 \tag{1}.$$
I'm a little confused on two points. Firstly, ... |
In this paper:
https://doi.org/10.1088/1367-2630/14/3/033044
it is show that for Kitaev toric code looses topological entanglement entropy over long times if it is thermally opened.
What is an example of a system which does not loose topological entanglement entropy over time at finite temperatures?
|
I recently learned about the dielectric that is used between the plates of a capacitor.
If $E_0$ is electric field between the plates of capacitor in free space and $E_i$ is electric field due to induced charge in a dielectric after it is inserted inside the capacitor, (Let the dielectric constant be $K$) It is known t... |
I think this is related to physics, and light waves.
Is there some materials that can be seen by human eyes and can't be seen by cameras? (Imagine a special writing) Is that even possible therotically?
|
The classic macroscopic variables one typically measures for an ideal gas are $P$, $V$, $T$, $n$, - pressure, volume, temperature, and amount, respectively. I am curious what the corresponding variables are for analogous system I'll call a 'bitgas', and the relationship between the infodynamics and thermodynamics.
A 'b... |
So this is what I understand from General Theory of Relativity:
A body freely falling towards earth's surface would be in an inertial frame of reference (air removed) with zero net force acting on it. This would cause weightlessness and would be equivalent to a body in spacetime (under no acceleration) with no gravitat... |
Subwavelength grating shows no diffraction orders of course except 0th order, then how will it get required momentum to match with Surface plasmon excitation? is it any role of evanescent wave?
|
I'm working on a project which calculates the some statics of a basketball shot. I haven't done physics since high school so I wanted to see if I was on the right track or if I'm completely wrong. Note: this is not a problem for school or nothing like that.
Currently the information I've got to work with is as follows:... |
Reading about the 'history' of beta decays and neutrinos, I learned that some early-twentieth-century physicists and chemists thought that the 'missing energy' of beta decays didn't go into Wolfgang Pauli's hypothesized 'neutrinos', but either just disappeared (violating conservation of energy) or resulted in an extra-... |
Suppose our plan is to measure experimentally the position $(x,y)$ in the plane and the momentum $(p_{x}, p_{y})$ of a quantum particle. Assuming the canonical commutation relation between $x$ and $p_{x}$, we will bypass so to speak the law by performing the following sequence of measurements:
$$ x \rightarrow p_{y}\ri... |
The title pretty much sums up the the question, what's the difference between massless neutrino flavours?
I know that an electron neutrino interact with the electron and so on for the muon and the $\tau$. I also get the basic of how they enter the standard model Larangian where they are in $SU(2)$ doublets and from the... |
Time passes slower for objects that move at near speed of light .
Since brain activity is based on signals that also need time to travel a certain distance, does the effect cancel itself out, or would you have "more time to think" while moving at a speed of light?
|
I'm trying to solve the following problem that I'm having a hard time with:
We have circle ${\Sigma}_1$ with center $O_1$ and radius $a_1$. The center $O_1$ is also the center of the static orthonormal coordinate system $R_0 (O_1, x_0, y_0, z_0)$. ${\Sigma}_1$ rotates at the angular speed ${\omega}_1$.
Be the circle ${... |
For starters, in the context of the tangent space of a manifold in GR, we can derive that:
$$g'_{\mu \nu}=\frac{\partial x^\rho}{\partial x'^\mu}\frac{\partial x^\sigma}{\partial x'^\nu}g_{\rho \sigma} \ \ \ \ \ \ \ \ (1)$$
where of course $g$ is the metric tensor and where we have indicated with $'$ the objects in the... |
The (15 positive) masses of fundamental particles are measured inputs to the standard model. They seem to increase exponentially when ranked in increasing order, or perhaps follow a power law when ranked in decreasing order. The masses (in GeV/c^2) are approximately:
0, 0, <.000001, <.00017, .000511, .0022, .0047, <.01... |
I'm reading notes from a friend of mine taking a quantum mechanics class, and I see something I don't quite get.
$$\left<x_i|x_j\right> = \delta_{ij}.$$
The notes say this implies orthogonality. Generally, the dot product of two orthogonal vectors is just zero, yes? So delta here = 0, but what exactly does $\delta_{ij}... |
Electric potential energy $U_e$ is defined as $k_e\frac{Q_1Q_2}{r}$. From that we get:
$$U_e=k_e\frac{Q_1Q_2}{r}=ErQ_2=F_er=W$$
Now, a lot of sources claim that $U_e=-W$. Why is work negative in this case?
|
Suppose we have got a triple of observables $A,B$ and $C$. Suppose furthermore, that $[A,B]=0$ and $[B,C]=0$ but $[A,C]\neq 0$ . Suppose, also now we do a measurement of $A$ then accordingly we would lose all information about $C$ because of the uncertainty in $C$. But notice that $[B,C]=0$ thus it follows that $B$ mus... |
If we have two entangled particles $A$ and $B$ and we separate them (supose that after entanglement, both travel at same speed in lab reference frame in opposite directions), then we measure a property of particle $A$ at time $t_0$ (lab reference).
Are we 100% sure that the particle $B$, if it didn't interact with anyt... |
I am looking for a relatively clean expression for matrix elements for states of the form $$\rho_{\alpha,r,\bar{n}} = \hat{D}(\alpha)\hat{S}(r)\rho_{th}(\bar{n})\hat{S}^\dagger(r)\hat{D}^\dagger(\alpha),$$ where $\hat{D}(\alpha)$ is the displacement operator with a complex parameter, $\hat{S}(r)$ is the squeeze operato... |
So I have this problem where I have to calculate circular speed but I don't have the mass. I can only do this by comparison.
So a ball rotates at $2.4 \ ms^{-1}$ with a radius of $0.8$ m. How much would be the velocity if the radius was reduced to $0.48$ m?
How can I do this by only comparing?
I tried calculate Period... |
I was thinking something
Let's consider radiation incident on a gas
If it were a bunch of electrons in place of photons, then incident electrons would increase the kinetic energy of each and every atom individually through elastic scattering. And since temperature is the average kinetic energy, increasing the KE of all... |
The typical way that I've seen Einstein's gravity expressed is by taking some spherical object, placing it into some sort of low-resistance space (like a very relaxed trampoline), and noting how it creates a funnel-like shape. Then, one proceeds to take an additional ball and spin it around the central object, thus exp... |
I am currently working on my Master thesis in a cold atom research group, and have irritatingly found -- or rather not found -- that no book or paper seems to explicitly mention what wavelengths are typically used for optical trapping. Our group uses 1064 nm light typically from what I gathered around the labs and offi... |
I ran an experiment where I split the light with mirrors like in the diagram below where the dots are photons and the lines are mirrors. I also attached an image to better illustrate it.
I ran two experiments, in the first experiment, I placed the mirrors symmetrically from the center(diagram 1). In the second experime... |
Let's suppose we have a scalar bosonic field in a coherent state configuration (for a single mode m). In Fock space, this would be represented as a coherent superposition of Fock states of all possible occupation numbers for mode m. If I understand it correctly, this roughly corresponds to a classical field configura... |
I am currently reading Guadagnini's The link invariants of Chern-Simons field theory, the part where he computes some examples of expectation values for different spaces.
For $S^2 \times S^1$, he uses one unknot with surgery coefficient $r=0$ to perform Dehn surgery on $S^3$. His computation is the following:
I can s... |
How does $F_{\mu\nu}F^{\mu\nu} = 2(B^2-E^2)$?
$$
F_{\mu\nu}=\pmatrix{
0&E_x&E_y&E_z\\
-E_x&0&-B_z&B_y\\
-E_y&B_z&0&-B_x\\
-E_z&-B_y&B_x&0
}
$$
$$
F^{\mu\nu}=\pmatrix{
0&-E_x&-E_y&-E_z\\
E_x&0&-B_z&B_y\\
E_y&B_z&0&-B_x\\
E_z&-B_y&B_x&0
}
$$
The matrix product:
$$
F_{\mu\nu}F^{\mu\nu}=
\left(
\begin{array}{cccc}
\text{E... |
I want to make sure the thing that triggers the vertical deviation (V-velocity) of a flow which is initially on horizontal path (U_Init != 0, V_Init = 0) then hit a vertical wall. Is it the pressure gradient and/or viscous forces from the Navier-Stokes equation? Apart the Slip/No-Slip condition, does it exist another b... |
When a metal surface is illuminated with light of appropriate frequency so as to cause photoelectric emission, when does the work function of the metal come into play? Is it the energy required to bring an electron to the metal surface or is it the energy required to liberate the electron from the metal surface?
Also, ... |
Suppose we are doing a measurement in a particular quantum field, i.e electron field. Are we looking for the probability of the electron to show up at that spot we are measuring or are we measuring the entire electron wavefunction (whatever that means)? Maybe it is checking every point in space?
I think mathematically ... |
For the Hamiltonian $H = \dfrac{p^2}{2m} - \mu S_z$, the eigenstates are the vectors $\begin{pmatrix} 1 \\ 0 \end{pmatrix} $ and $\begin{pmatrix} 0 \\ 1 \end{pmatrix} $. I understand these are eigenvectors of $S_z$. I was wondering however what the momentum of these states are. Would they be $0$, since differentiation ... |
Can, in any condition, the string or string-like objects provide normal force to any object getting supported by it? Maybe when the string is taut!!
|
I have read that the attenuations of microwave transmission lines and optical fibers are ~1 db/m and ~ 0.2 db/km, respectively. I understand that these values depend on the geometry, design, and frequency of the carrier signals.
However, I was wondering if there is an inherently physical reason behind such a stark diff... |
Consider fermion DM with g internal degrees of freedom and the statistical distribution results in:
$$f(E) = \frac{g}{ \exp[(E − µ)/T] + 1}$$
with $g = 1$ when $E < µ$
and $g = 0$ when $E > µ$
When I integrate $f(E)$ the phase-space, in the relativistic limit, distribution I get this:
$n = \frac{gT^3}{2\pi^2} \int_0^{\... |
Is it true that among all the ways to travel a distance $X$ with an average speed $E$ in the speed vs. distance graph, traveling with a constant speed $E$ minimizes the time it takes to complete the travel?
If yes, then is there any other way to travel for which it also takes that minimal time to complete the travel?
N... |
In reading "Density functional theory of atoms and molecules" by Parr and Yang, I was not sure what is meant by this sentence when the Virial theorem was introduced.
Suppose I have a Hamiltonian $\hat{H}$ for that describes some molecule.
"The kinetic energy component
$\hat{T} = \sum_i\frac{1}{2}\nabla_i^2$ is degree -... |
I am trying to calculate the following divergent integral, I cite directly from the book
$$\begin{align}
V\left(\phi_{c}\right) &=\frac{1}{2} \mu^{2} \phi_{c}^{2}+\frac{\lambda}{4 !} \phi_{c}^{4}-\mathrm{i} \int \frac{\mathrm{d}^{4} k}{(2 \pi)^{4}} \sum_{n=1}^{\infty} \frac{1}{2 n}\left[\frac{(\lambda / 2) \phi_{c}^{2... |
I am curious about how to calculate the precise location of a projectile.
Assuming that acceleration due to gravity is $-9.81 \text{ms}^{-2}$, how would you calculate the displacement of a tennis ball including drag. Given the angle $\theta$, the initial velocity $v$, and a vertical distance d, from ground level.
Given... |
The electric field $\mathbf{E}$ and the magnetic induction $\mathbf{B}$ can be parameterized in terms of potentials $V$ and $\mathbf{A}$: $$ \mathbf{E}=-\nabla V-\frac{\partial \mathbf{A}}{\partial t},\quad \mathbf{B}=\nabla\times \mathbf{A}.$$ This parameterization is not unique, as we can find a scalar function $\the... |
I encountered this diagram when reading an explanation about why the front wheels of cars lift up when they accelerate. The diagram is in the reference frame of the car, so that there is a fictitious force $MA$ on the center of mass. $f_1$ and $f_2$ are the frictional forces on the wheels. Now the car is not moving ba... |
I would like to get an understanding of the value of the Hagedorn temperature and the units this temperature can be given in. Is the Hagedorn temperature the maximum temperature, just as $0\ K$ is the lowest temperature? What happens to matter when the Hagedorn temperature is reached?
|
As perhaps a mathematical scavenger hunt, my mother (knowing my interest in physics and math equations), sent me this image out of curiosity for what it was.
Here is the same equation taken from the image:
$$\gamma^\mu(i\partial_\mu-eA_\mu)\psi=m\psi$$
I've attempted to reverse image search it to no avail. With it's r... |
How would I find the time evolution of the standard deviation of an operator? For example, how might I find the time evolution $\sigma_x (t)$ of the standard deviation
$\sigma_x = \sqrt{ \langle \hat{x}^2 \rangle - \langle \hat{x} \rangle^2}$
of the position operator $\hat{x}$ given a state $| 0 \rangle$ representing a... |
Suppose a body is slowly descending in a downwards firing rocket, in a tunnel dug through Earth's surface, and switches off the rocket just as it reaches earth's COG. Now since the body reached the Earth's COG with 0 velocity, according to me it would remain suspended there with the COG and body locally becoming inerti... |
Consider a ferroelectric plate capacitor connected to an AC source in the presence of a strong static external electric field which sets the ferroelectric medium in the saturated regime.
The question:
Does the static polarisation $P$ of the ferroelectric have an influence on the capacitance $C$ of the capacitor?
Two co... |
In vacuum, the energy density of the electric field is given by $\mathcal{E}=\epsilon_0\frac{E^2}{2}$ with $E$ the total electric field present. So, if you have a static $E_0$ and dynamic $e(t)$ field, the energy density becomes
$$\mathcal{E}=\epsilon_0\frac{\left[E_0+e(t)\right]^2}{2} = \epsilon_0\frac{E_0^2 +2E_0e(t)... |
I'm trying to understand how we can get rid of the ${\rm U}(1)$ theta term (whose $\theta$ I call $\theta_1$) in the SM.
In Schwartz's QFT textbook he writes
Before discussing the strong CP phase further, we note that the ${\rm SU}(2)$ and ${\rm U}(1)$ angles can be removed completely by chiral rotations. We saw that ... |
Suppose I have two arbitrary electric fields (vector fields), $\mathbf{E}_1 (\mathbf{r})$ and $\mathbf{E}_2 (\mathbf{r})$, which are a function of position $\mathbf{r}$ (the $e^{i\omega t}$ is implicit). The wave vectors of these fields are $\mathbf{k}_1 (\mathbf{r})$ and $\mathbf{k}_2 (\mathbf{r})$. I understand that ... |
Does anyone know what the energy spectrum for the entire universe looks like? In other words, what would the graph look like if you plotted the number of photons on the $y$-axis and frequency on the $x$-axis? Would it look like a blackbody spectrum, what would the peak temperature be?
|
What is the anti-triplet representation of a group?
Specifically, what is the anti-triplet representation of $SU(3)$?
|
The problem says:
A cylindrical chandelier is hung on a wire and when it rotates around its siege an angle $\theta$ the twisting moment acting on it is $\tau$ = $−\theta$. The moment of inertia is unitary and its angular velocity in the equilibrium position is unitary. Calculate the maximum twist angle $\theta_0$, ...
... |
I can't see how path difference and central maximum (where path difference is 0) work when there are more than 2 wave sources.
When a beam of white light passing through a diffraction grating, it is obvious that the central maximum is a white fringe, while other bright fringes are arranged in spectra (due to the compos... |
Ohm's law is often motivated by the microscopic relation
\begin{align}
\vec{j} = \sigma \vec{E}
\end{align}
From this you can easily derive
\begin{align}
U = RI
\end{align}
, given that
\begin{align}
U = \int_{\text{along the resistor}} \vec{E} \vec{ds}
\end{align}
However, there are different definitions of "voltage",... |
In article Deriving Projective Hyperspace from Harmonic there is discussion of JWKB (page 7) path integral for free fermion.
Here I briefly rederive the statement:
If one start with Lagrangian:
$$
L = \bar{\psi}\dot{\psi}
$$
And perform path integration through discretisation ($t_1-t_0 = N\epsilon$):
$$
Z = \int D\psi ... |
The coefficient of restitution is defined as the ratio of the differences in velocities of colliding objects after and before the collision: $$k_{COR}=\frac{v_{1,after}-v_{2,after}}{v_{1,before}-v_{2,before}}.$$ There also exists a second definition, where $$k_{COR}=\sqrt \frac{E_{k,after}}{E_{k,before}}.$$
As such, in... |
If I can set the divergence of $A$ as whatever I want, won't it affect Ampere's law:
$$\nabla ^{2}A=-\mu_0J$$
I could set it to zero and that would mean $\nabla 0=0=J$
I have understood the proof given in Griffiths where we are able to find a scalar function using Poisson's equation which in turn proves that we can alw... |
How to get the second equation, please? My result is wrong - I still have $(N-1)$. Thank you
|
It is well-known that a major open question in physics is why the Universe appears to be made almost entirely out of matter, with next to no antimatter, despite the two being strictly symmetrical under the standard model. I know that it has to do with the breaking of the CP symmetry in some way. When researching it, I ... |
Neutrinos with specific mass don't have a unique flavor and neutrinos with specific flavor don't have unique mass.
Let's call the neutrinos with specific mass $\nu_1, \nu_2, \nu_3$ and the neutrinos with specific flavor $\nu_e, \nu_\mu, \nu_\tau$.
According to the subatomic stories of Fermilab
\begin{align}
\nu_1 &= \{... |
I'm going through Cardy's "Scaling and Renormalization in Statistical Physics", and I've run across a notational confusion. Consider a 2D Ising system with the following Hamiltonian
$$\mathcal{H}(s)=-\frac{1}{2}\sum_{r,\bar{r}}J(r,\bar{r})s(r)s(\bar{r})-\mu H\sum_{r}s(r).$$
We now would like to perform a block transfor... |
Question
Suppose you perform a gauge transformation $f(x)$ that is only $n$ times differentiable, for any $n$. Can the discontinuity in the $(n+1)^{th}$ derivative change any observable?
Clarification
I understand that the answer to the question for small values of $n$ is obvious. If $F_{\mu \nu} = \partial_{\mu} A_{\n... |
When reading Sterile neutrino hot, warm, and cold dark matter I came across the following momentum distribution function for a neutrino species $\alpha$:
$$\tag{5.8} f(p,t) = \frac{1}{e^{E(p)/T + \eta_{\nu_\alpha}}+1}$$
where $\eta_{\nu_\alpha}= \mu_{\nu_\alpha }/T$ and $E(p) \approx p$.
Why is the function $f$ a funct... |
Recently I have come to know that for a system with $2n$ dimensional phase space, the set of all canonical transformations form a group ${\rm Sp(2n, R)}$. But in contrast to other Lie groups e.g. ${\rm SO(3)}, {\rm SU(2)}$ etc, I find this group to be quite abstract. Let me explain.
Any matrix $M\in{\rm Sp(2n, R)}$ act... |
In "Applied Frequency Domain Electromagnetics" (here the page) there are these two equations for the computation of the magnetic and electric energies stored in a certain volume $V_0$:
$$W_{e}= \frac{1}{4} \cdot \int_{V_0} D^* \cdot E \,\,\,dV$$
$$W_{h}= \frac{1}{4} \cdot \int_{V_0} B^* \cdot H \,\,\,dV$$
Where E,D,H... |
How does the observation of strangeness enhancement in high-multiplicity proton–proton collisions explain the existence of quark-gluon plasma?
|
This might seem like a silly doubt but I am confused about this.
For what kind of waves is the wave equation in 1+1D satisfied?
$$\frac{\partial^2 f(x,t)}{\partial x^2}=\frac{1}{v^2}\frac{\partial^2 f(x,t)}{\partial t^2},$$
where $f(x,t)$ is the disturbance of the wave at position $x$ and time $t$ and $v$ is the veloci... |
Let us suppose that there is a constant uniform magnetic field perpendicular to the surface of a block of iron. Why does the magnetic field increases inside the block? Is it due to the alignment of the small magnetic dipoles in the direction of magnetic field? If this is so, is it analogous to the field developed insi... |
There are two types of photons, positive and negative helicity photons. What would Maxwell's equations look like say if there were only negative helicity photons? It would be interesting to see this in any of the forms of Maxwell's equations; e.g. in the form of the field strength tensor $F^{\mu\nu}$, or in the form of... |
Moore and Seiberg (1989) prove that rational CFTs are classified by the braiding matrices
$$
B\begin{bmatrix}j_1&j_2\\i&k
\end{bmatrix}\colon \bigoplus_p V_{j_1p}^i\otimes V_{j_2k}^p\to V_{j_2q}^i\otimes V_{j_1k}^q
$$
which implement the duality transformations between different blocks
I am looking for the values of t... |
I want to write the matrix form of a single or two qubit gate in the tensor product vector space of a many qubit system. Ill outline a simple example:
Both qubits, $q_0$ and $q_1$ start in the ground state, $|0 \rangle =\begin{pmatrix}1 \\ 0 \end{pmatrix}$. Then we apply the Hadamard gate, $\begin{pmatrix} 1 & 1 \\ -1... |
There are two ways when dealing with spin system(Heisenberg model): non-linear $\sigma$ model and Schwinger boson.
Non-linear $\sigma$ model
When taking large $S$ limit, the quantum fluctuation of spin will be suppressed, which is so called "semi-classical" approximation. This means the start point is the classical con... |
I was just studying condensed matter theory and in particular was examining models for crystal solids. I found that an introductory classical model used is the one of coupled harmonic oscillators. One could also add one anharmonic term to it and model the same type of solids (In fact this is called the Fermi-Pasta-Ulam... |
The free Green function:
$$G(k)=\frac{1}{k^2+r}$$
I want to derive its form in real space(assuming the most trivial Euclidean metric) :
$$G(x)=\int d^D k \frac{e^{-ik\cdot x}}{k^2+r}$$
for two-dimension, i.e. $D=2$, it can simplified as:
$$G(x)\sim\int_0^\pi d\theta \int_0^\infty d k \frac{ke^{-ik x cos\theta}}{k^2+r}$... |
Since the mass of elementary particles are very small, I'm wondering why we call particle physics "high energy physics", why shouldn't it be low energy physics?
|
(The question is by a friend of mine, who is a physicist.)
Background: There have been many research papers about electrostatic waves in a degenerate electron gas in a neutralizing background, and there are two widely known theoretical approaches to study them:
The simplest approach is to use the Vlasov equation and a... |
I am trying to solve the problem of the collision of any two rigid-bodies. So far this is what I got:
I am concerned with the part where I reduce the equation with the coefficient of restitution by $\vec{n}$. As far as I know it can be factored out and the fraction, reduced. Yet, I am unsure as it seems to me, that it... |
My confusion is about the different Hilbert spaces we meet in QFT.
In a first introduction to QFT, the Hilbert space is often taken to consist of wavefunctionals on classical fields on $\mathbb{R}^3$. In this picture, the state as seen by a given observer contains information about what is going on at all points of spa... |
Does level of water have any effect of the capacity of cooling in a desert cooler ?
The fan rotate with a constant angular velocity so how and why does the water level effect the coolness capacity of a cooler ?
|
When I make a function to represent an object's position at intervals of two seconds, and it is parabolic, for example $f(x)=\dfrac{5x^2}{2}$ with the following points:
$ \text{seconds} \ \ \text{metre} $
$ 0 \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 0 $
$ 2 \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 10 $
$ 4 ... |
There are a lot of questions on this site about photons and wavepackets.
Relation between radio waves and photons generated by a classical current
This one lists a lot of them as reference. None of them in detail specifically answers my question.
What happens when a photon hits a beamsplitter?
I have read this:
https:/... |
Integrals of the form
$$\langle{\phi(x_1)\cdots\phi(x_n)}\rangle=\frac{1}{Z}\int\mathcal{D}\phi\,e^{-\frac{1}{\hbar}S(\phi)}\phi(x_1)\cdots\phi(x_n)$$
can be evaluated by considering Feynman diagrams with tails labelled with $\phi(x_1),\dots\phi(x_n)$. I have recently come across with a related notion of computing
$$\f... |
Say we have a basis of two wave functions $|\psi_1\rangle$ and $|\psi_2\rangle$, and make a unitary transform with the matrix $U=\left[\begin{array}{ll}0 & 1 \\i & 0\end{array}\right]$. This is the same as multiplying one of the wavefunctions by a relative phase $e^{\phi i}$, but what exactly is the phase we are multip... |
I have a chart that displays conformal time on the vertical axis, comoving distance on the horizontal axis. The values are in units of billions of years (Gyr), but scaled logarithmically such that $$F(x)=\log_{10}\left(\frac{G(x)}{\text{Gyr}}\right)$$
How would you label this axis?
My first pass: $\text{Conformal Time... |
an optical cavity is "an arrangement of mirrors that forms a standing wave cavity resonator for light waves" (wikipedia).
The possible standing wave patterns for such structure are like these:
As you can see, the vertical black lines (which are the mirrors) are the nodes of the standing waves, since they force the wav... |
This is a relativity question: how it is possible that we can measure, using Doppler effect, the relative speed to a star that is many light years away, establishing relative velocity with a source that could not know who will see its emissions?
|
How can we prove the boundary conditions of the magnetic field $\vec{B}$ that the tangential component of the magnetic field changes when magnetic field lines travel from one medium to another?
|
In Wayne Hu's tutorials, as well as Wikipedia, I've seen the CMB quoted as being isotropic to 1 part in 100,000. I tried to get a reference for this, so I dug and found out that, after subtracting the dipole, the CMB has a standard deviation of $18 \mu K$. So I did the calculation myself:
$$\frac{2.7522 K}{18 \mu K}=... |
If you take the ideal gas law and substitute $\dfrac mM$, where $m$ is mass of the particles and $M$ is molecular weight, you can derive $D = \dfrac{MP}{RT}$ with algebraic manipulation, where $D$ is density.
From this, I initially thought that pressure was dependent on mass since mass and pressure are both on numerato... |
I'm wondering why supersymmetry can only be verified in high energy level,can we check supersymmetry in low energy physics?
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Classically, if you wiggle an electron in a sinusoidal pattern up and down, you get a smooth electromagnetic wave that propagates, kinda like when you wiggle a jump rope. Do this fast enough and you can get visible light.
However, then there's the Nobel-prize-winning idea that light comes in packets called photons. But... |
What is the difference between isolated neutron stars and neutron stars?
What is the meaning of isolated here?
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