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can ions moving in a solution generate magnetic field if yes then why is it not more commonly used. lithium ion's in batteries pass from cathode to anode separated by a membrane to discharge the current. does this movement generate a significant magnetic field.
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(Mathematician here - first time physics.stack poster).
I'm basically looking for as simple as possible explanation of the Hamiltonian - Lagrangian relationship.
$\textbf{My understanding :}$
$\textbf{The Hamiltonian.}$
Say we have some particle in $\mathbb{R}^d$, with a position $q(t)$ and velocity $\dot{q}(t)$, i.e e... |
There are 2 ideas of symmetry I have seen in Classical Mechanics:
Noetherian symmetry: Here they discuss infinitesimal point transformations where only position coordinates (and their derivatives ) get perturbed. They define symmetry to be those infinitesimal transformations where Lagrangian is not changed. Noether's ... |
I'm a little confused about the integral definition of the Komar mass, and how it gives the correct result for vacuum solutions.
As given by Poisson, the Komar mass is
$$
M_{Komar} = \int \left(2T_{\alpha\beta} - T g_{\alpha\beta}\right)n^\alpha\xi^\beta_{(t)}\sqrt{h}d^3y,
$$
where $n^a$ and $\xi^\beta_{(t)}$ are the n... |
I understand that Ytterbium can emit a photon with a relatively high and very accurate frequency (narrow band of frequency). I also know that Ytterbium is being used to verify frequency in atomic watches (a photon with the right frequency can be absorbed, so if the frequency is shifted than the the light will be reflec... |
Considering a homogenious and isotropic universe described by the Robertson-Walker metric:
$$ ds^2= dt^2-a^2(t)\left[\frac{dr^2}{1-kr^2}+r^2(d\theta^2+\sin^2(\theta)d \phi ^2)\right]$$
and also assuming that this universe is dominated by a scalar field $\phi (t)$ and a potential of the form $ V(\phi)=V_0e^{- \lambda \p... |
The total kinetic energy of the system:
(A) will be equal to 1/2 mv^2
(B) will always be less than 1/2 mv^2
(C) will be greater than or equal to 1/2 mv^2
(D) will always be greater than 1/2 mv^2
The answer given in my book is (C)
I tried using the approach:
Total K.E. of system= K.E(centre of mass) + K.E(of masses wit... |
While explaining Centre of Mass, my teacher told this exact statement that "If net $F=0$ on a system then KE of the system may change due to internal forces or due to internal work done."
Let's take 2 positive charges "q" and place them at distance "d".
My query was it's right that KE of the system can change due to in... |
I am trying to understand the renormalization group approach to phase transitions. A central quantity is the correlation length $\xi$ given by $G(r) = \langle\phi(r)\phi(0)\rangle \sim e^{-r/\xi}$ for $r \to \infty$. A phase transitions occurs when $\xi$ diverges.
The renormalization group approach is based on the idea... |
In "The electrodynamics of moving dielectrics" (p. 262) Landau and Lifshitz have defined four-tensors and four-vector
$F^{\mu \nu} =
\begin{pmatrix}
0&-E_x&-E_y&-E_z\\
E_x&0&-B_z&B_y\\
E_y&B_z&0&-B_x\\
E_z&-B_y&B_x&0\\
\end{pmatrix}$
$H^{\mu \nu} =
\begin{pmatrix}
0&-D_x&-D_y&-D_z\\
D_x&0&-H_z&H_y\\
D_y&H_z&0&-H_x\\
... |
I've been learning Green's Function approach recently, following Radi Jishi's book. It says that the imaginary-time Green's function (Matsubara function) cannot be used in non-equilibrium situations, which makes me wonder why because I don't see where we impose the equilibrium condition when we derive the perturbative ... |
It is recognized that special relativity does not require the speed of light to be isotropic, and having light propagate in each direction with the same speed is just a convenient postulate (see e.g. this Wikipedia article and references therein, or a recent popular science video on YouTube).
I was wondering how would ... |
With matter a type of energy, can/should the universe be considered a thermodynamic system? At what scale would it be relevant?
|
What is $\left(\frac{\partial P}{\partial V} \right)_V $ ?
Mathematically its undefined but how to understand it for thermodynamic system like ideal gas?
Or in other words, is $\left( \frac{\partial V}{\partial P} \right)_V $ identically zero ?
|
Consider charge particle $q$ in electric field $\mathbf{E}$. The force on the charge is given by
$$\mathbf{F}=q\mathbf{E}$$
Now we know that charge $q$ will also produce an electric field. Due to this field, the field already present in the space should be modify. And thus we should use the modified version of the fiel... |
For a photon or anything that travels at the speed of light, time is dilated infinitely, meaning there is no time. Also, length along the direction of motion is dilated infinitely, meaning the length of the universe along that direction becomes zero. Is this interpretation correct? How do you make sense of this? Does i... |
Can somebody prove the rotation of Earth if it places an uniform disk with a hole in its the center on an axis and orient it paralelly to Sun ecliptical disk?Just assure himself that the disk on the axis is in equilibrium and the friction between the disk and axis at the center hole of the disk is negligable. The disk ... |
What is the reason why the exclusion plots of WIMP experiments have that "U" like shape? And what sets the minimum of the curve?
|
I know of several definitions of phases of matter:
The first is the "old" one, Landau theory and symmetry breaking. In this definition we pick a local order parameter $m$ (as far as I can tell this is quite vaguely defined). If the state had the same symmetry of the Hamiltonian, we would have $\langle m\rangle=0$, but... |
Consider the Hamiltonian
\begin{equation}
H = a^\dagger a + c^\dagger c + \text{i} \xi \left( a^\dagger - a \right) \left( c + c^\dagger \right),
\end{equation}
where $a$ and $c$ are bosonic annihilation operators obeying $[a,a^\dagger]=1$, $[c,c^\dagger]=1$ and $[a,c^\dagger]=0$, and $\xi>0$. The normal mode opera... |
Charts of particle flux tend to show the flux rate in units of particles per metre squared per second per steradian per MeV. I don't understand what the "per MeV" is referring to. How do I convert particle flux units per MeV into particle flux units (without the MeV part)?
In Figure 1 in this paper, in the middle of th... |
I understand that if $\psi$ is a many-body electronic state function and
$$
g(x) = \int \psi^*(x,x_2,\cdots,x_n) \psi(x,x_2,\cdots,x_n) \, dx_2\cdots dx_n,
$$
then $g$ describes the probability to measure a particle in a volume element at $x$. And if I add the prefactor $n$, it becomes the density, simply because the d... |
Consider the hydrodynamic energy-momentum tensor in 3 + 1 dimensions in
at space with
the Minkowski metric $\eta_{\mu\nu}$. The coordinates are chosen as $u^\mu = (t; x; y; z)$. To first order in
derivatives, the energy-momentum tensor can be written as
$T^{\mu\nu}=(\epsilon+P)u^\mu u^\nu+P\eta^{\mu\nu}-\eta\Delta^{\mu... |
Let's suppose we have an electron hopping around on a lattice; for the simplest case you can take for example a 1D chain of Hydrogen atoms, described by the Hubbard model (see https://en.wikipedia.org/wiki/Hubbard_model). So the Hamiltonian has a term for interaction between an electron and an atom when the electron is... |
I'm reading through Nakahara's Geometry, Topology and Physics and I don't understand the following derivation on pg. 41:
$$
\text{Now we find from the commutation relation of } \partial_x \equiv \frac{d}{dx} \text{ and } e^{ikx} \text{ that}
\\
\partial_x e^{ikx} = ik e^{ikx} + e^{ikx} \partial_x = e^{ikx} ( ik + \par... |
The paper "Supersymmetric Gauge Theories, Intersecting Branes and Free Fermions" asserts (first paragraph, page 12,section 2.4) that a system of $N$ $D4$-branes intersecting with $k$ $D6$ branes along two flat directions (say on a 2-torus) is supersymmetric. The paper suggests that this can be shown by mapping the sys... |
Does a magnetic field always have rotational symmetry? If not, would someone mind giving me an example?
|
Consider a non-interacting fermion system with Hamiltonian
\begin{equation}
H = \sum_{\nu}\epsilon_{\nu}c^{\dagger}_{\nu}c_{\nu},
\end{equation}
where $\nu$ is some single-particle quantum number. It can be shown that even in finite temperature, if we define the retarded Green's function as
\begin{equation}
G^{R}(\nu,t... |
In the derivation of the Kraus decomposition, it is not clear to me how to get from the LHS to the expression on the RHS: $$ \text{Tr}_{env}[U(\rho_1\otimes \rho_{env})U^\dagger]=\sum_k\langle k|U|0\rangle \rho \langle 0|U^\dagger|k\rangle, $$ where we substitute $\rho_{env}=|0\rangle\langle 0|$ and using a basis for ... |
If you run a current through a solenoid, does it have any magnetic flux on its own of does it need an externally produced magnetic field for there to be any net flux through the solenoid? The physics problem I am doing consists of 2 coaxial solenoids. One is inside of the other. When calculating the flux through the in... |
is there a way to have two space clocks synchronized? and if the answer is yes, if it travels towards me in a uniform rectilinear way (and from its perspective I will do the same) what will our clocks mark when we meet if the time dilation is symmetrical?
|
Being so close to Mars, Phobos should receive a non-negligible amount of irradiance from Mars. Be it from reflected sunlight, Mars' emitted infrared radiation, or other factors. I have no idea how to calculate those however.
|
I am looking for help with a question relating to thermodynamical identities in differential form.
Any help or hints are appreciated.
I have included my progress so far for reference:
$T$ denotes temperature, $V$ denotes Volume, $U$ is energy, $S$ is entropy and $p$ is pressure
(1) has been proven
$$(\frac{\partial U}{... |
I have a datalogger that records temperature and relative humidity in a room. Can I use that to calculate vapor pressure?
|
I wanted to try to make a sphere (with net charge $q$) float with electrical force so I applied the fact for the ball to be at rest the net forces to be 0. I assumed the only other force than gravity would be the Lorentz force. And if the ball is staying still in the air then the velocity field is the 0 vector. Then $F... |
In p.191, Chapter 5 of Weinberg's QFT, he is arguing about the inevitability of the quantum fields from Lorentz-invariance and cluster decomposition principles. He says
The S-matrix will be Lorentz-invariant if the interaction can be written as
$$
V(t)=\int d^{3} x \mathscr{H}(\mathbf{x}, \mathbf{t})
$$
where $\mathsc... |
I know it is because the electrons in hydrogen and helium absorb them however, they also drop back to ground state immediately and emit the previously absorbed photon. So there should be no net difference as absorbed photon gets emitted. Therefore the emission spectrum should not have missing lines. But they do. What a... |
From the photoelectric effect, we know that a photon can kick an electron outside the atom if it has the right amount of energy ($E_{\gamma} \geq W_0$).
On the other hand, pair production tells us that a photon can annihilate to form an electron and an anti-electron (positron).
I'm wondering, how do we know that a phot... |
Today in Quantum we talked about a 3 component quantum channel; maximally mixed light flowing into a linear filter oriented to 0 degrees, to through a phase retarder, then through another linear filter oriented at 90 degrees. If the phase retarder were removed, no light would make it through the channel, but with it, l... |
I'd like your help regarding this thermodynamics problem:
When trying to solve it I found that there is a problem with the leaks in the cylinder caps, and it occurred to me that to avoid the problem with caps it would be useful to consider it to be infinite in length and
than the amount of heat per unit
length would be... |
I learnt that one of the demerits of Bohr's atom model was that it couldn't explain fine spectrum because the atom would emit only certain values of energy when excited.I was wondering if the quantum mechanical model has resolved it..
|
Why for the same turbine exit condition, if the pressure and temperature of the air vapor entering the turbine are increased, the power produced by the turbine is greater?
|
Consider the following thought experiment. There is a floating generator that produces high voltage EMF. A man standing with bare feet touching the earth surface. I heard that our earth is always hungry of electrons so it will absorb electrons as many as available. But how can the electrons flow if only one end is bein... |
In the following the second part of the question Relativistic hydrodynamics is presented:
Consider the hydrodynamic energy-momentum tensor in 3 + 1 dimensions in
at space with
the Minkowski metric $\eta_{\mu\nu}$. The coordinates are chosen as $u^\mu = (t; x; y; z)$. To first order in
derivatives, the energy-momentum t... |
Textbook suggests that before conducting a double slit experiment, incoherent light is first passed through a single slit to make a coherent point source of light; the point source can be explained by Huygen's Principle.
However, how would incoherent light before the slit become coherent if the point sources are create... |
According to Planck's law, E=hf is applicable for photon and photon shows wave-particle duality. But De Broglie proved that Electron and other substances also shows wave-particle duality and he showed that
lambda=h/p. But I have some problem about this topic. This is: mc^2=hf or, mc^2=hc/lambda or, mc=h/lambda or, lamb... |
Assume that a diver performs $3$ different jumps, at the same initial speed from a platform $10m$ high (straight into the water, one spin, two spins). What is the time difference in reaching the water surface?
How do you explain in physics.
|
I have seen so many times this partial differrential equation like this:
$$\frac{\partial ^2 y}{\partial x ^ 2} =- \omega^2y $$
has solution $$y = A \sin(wx) + B \cos(wx)$$
similarly: $$\frac{\partial ^2 y}{\partial x ^ 2} = \omega^2 y$$
has solution: $$y= Ae^{\omega x}+Be^{-\omega x} $$.
We can check that the soluti... |
Forces like the electric force has a Coulombs constant $k_e$ from the Coulomb's law
$$
F=k_e\frac{q_1q_2}{r^2}
$$
, which is based on the vacuum permittivity $\epsilon_0$. However, the magnetic force can be directly calculated from the scales of charge, velocity and magnetic field strength in SI units by Lorentz law.
$... |
The proof that $LL^\dagger$ is Hermitian, where $L$ is a linear (but not necessarily Hermitian) operator, is usually given in terms of the inner product, i.e:
\begin{align}
\langle \phi |LL^\dagger |\psi \rangle &= \langle \psi |(LL^\dagger)^\dagger |\phi \rangle^* \\
&= \langle \psi |(L^\dagger)^\dagger (L)^\dagger |\... |
I want to calculate $\langle p_x\rangle$ and $\langle p_x^2\rangle$ for ground state electron in $\rm H$ atom.
Radial function
$$
\psi(r)=Ae^{-r/a}
$$
Momentum operator in 3D:
$$
\hat{\vec p}=\frac{\hbar}{i}\left(\frac{\partial}{\partial x},\frac{\partial}{\partial y},\frac{\partial}{\partial z}\right)=\frac{\hbar}{i}\... |
Is the De Broglie wavelength of a quantum entity same as the wavelength of its wave function?
If yes, why? If no, why? If it is true only under certain circumstances, what are the conditions?
|
I know that the time constant $\tau= RC$, where $R$ is the resistance and $C$ is the capacitance.
But I'm confused, bear with me, when I double or increase the capacitance of the RC circuit.
If I double the capacitance of the RC circuit, will the time constant be also double, or half of its original value? Can the same... |
Why do we not consider rate of change of acceleration in the study of linear motion?
|
I know that in case of cart moving with an acceleration we are supposed to apply the concept of pseudo acceleration to judge the motion of ball in frame of the cart.
Now , consider the case where cart is moving with constant velocity. What will be the trajectory of the ball? Is there something called pseudo velocity?... |
I just wanted to know why is this possible:
$$\int_{i}^{f}-\frac{dU}{dr}\overrightarrow{e_{r}}\cdot (dr\overrightarrow{e_{r}})=\int_{i}^{f}-dU$$
Could someone help me figure out what is happening with that dot product?
P.S.: Integrating vectors tips are welcome (I'm a first year)
|
There are many examples of media non-transparent for the light of visible spectrum.
What does it mean in terms of the Maxwell equations in such media? More precisely what does it mean for dielectric permittivity and magnetic permeability (which depend on the medium and on the frequency of the light)?
|
The experiment says that if I split a photon into two coherent entangled photons, one towards a double-slit, one towards a which-way detector, I can control whether
the interference pattern appears by choosing either detecting which way the photon came through or
destroying the information about the photon, even if th... |
How can we relate the measured data of speakers with its SIZE (speaker)? I have the data on white noise and pink noise (FFT and 1/3 octave), I'm a bit confused about how to show the relationship (connection) between them.
Here I have 2 speakers, one is a car speaker and the other is a large one.
|
If E=hf is applicable for electron and other particles, the De Broglie wavelength should be λ=hv/pc. Because, mc^2=hf which implies mc^2=hc/λ which implies m=h/λc and thus λ=hv/pc. But I have found in my text book that λ=h/p is applicable not only for photon but also for all particle. But how can λ=h/p=h/mv be applicab... |
I have 2 airplanes and I would like completely hide the communications between them.
There is a possible way that this communications would not be detected by our radio receivers around the world? Would be possible to simple hide it?
What alternative technology can be used achieve this? And why we would not detect this... |
I would like to deduce that for a metal strip if the coefficient of thermal expansion ($\beta$) is constant then for a temperature increase $ \Delta T $ the new length will be $l\approx l_0(1+\beta\Delta T)$
But I'm a little bit stuck. On another book says that $l=l_0e^{\beta\Delta T}$
so it's easy for me to go from th... |
The time-dependent Schrödinger equation is
$$
\hat H \Psi = i\hbar \partial_t \Psi
$$
When solving this equation for the hydrogen atom (in position space) by separation of variables, one gets not only the the eigenvalues of the hamiltonian (i.e., possible energies), but also the quantum numbers $\ell$ and $m$, which ar... |
Background of the problem:
The problem I am currently struggling is related to the momentum representation of Fourier transform. Briefly speaking, the integral in Minkowski under Cartesian coordinate is,
\begin{align} K(\vec x,\vec z) = \int^\infty_{-\infty} d^3y\int^\infty_{-\infty} \frac{d^3p}{(2\pi)^3} \int^\infty_{... |
I have been reading a paper about the production of respiratory droplets in human respiratory tract and learned that they are produced due to instabilities, which includes the Rayleigh Taylor instability. Wikipedia contains examples about Rayleigh instability but I couldn't understand what instability means in the cont... |
I am attempting to solve a homogeneous heat equation
\begin{equation}
u_t = \alpha^2 u_{xx},
\end{equation}
with an initial temperature $u_0$, and time-varying boundary conditions $u(0,t) = u(L,t) = u_s(t)$. The challenge is that the function $u_s (t)$ isn't a continuous function that can be expressed neatly, but rathe... |
When deriving Bernoulli's equation, $\mathbf{F}=m\mathbf{a}$ for a small fluid particle is applied to streamline and the direction normal to streamline. During this operation, why is 'delta' specifically used for particle mass, volume as opposed to $d$ as in $dV$, $dxdydz$ or $dm$. Is this utilization of the Dirac delt... |
Recently learnt some physics, and I just want to check my understanding
|
¤The statement above this circuit in my book reads 'the (conventional) current should flow into the ammeter through the positive red terminal and leave through the negative black terminal', as the switch is open here, in a real setup ammeter would not show the electric current measurement as the current won't be able ... |
In standard particle physics textbook, we say that photons, gluons and $W$ and $Z$ bosons are gauge bosons as elementary particles.
However the gauge bosons are vector bosons and they carry the form of one form gauge field, and have gauge invariant form such as a closed line as
$$
tr_R \left[\exp(i \oint A)\right],
$$... |
I have given the Schur's Lemma in following version:
Let $R:G \rightarrow \text{U}(\mathcal{H})$ be an irreducible representation of $G$ on $\mathcal{H}$. If $A \in \text{L}(\mathcal{H})$ satisfies
$$A R(g) = R(g) A \quad \forall g \in G$$
then $A = c I$ for some $c \in \mathbb{C}$.
Here $\mathcal{H}$ states a finite ... |
I read in a paper that as particle size decreases and it reaches a limit, the particle no longer has gravitational force as its dominant force and it starts to travel in the air for long times. Aerosols are such particles.
Which force is dominant on such particles then?
With that knowledge, is it possible to find the ... |
Is electric potential real? You might say it depends on what I mean by 'real' and I agree. But I remember reading about an experiment suggesting that electric potential is real, contra what had been previously thought. Are there any experiments that could have some bearing on the reality of electric potential?
|
Every reference I have seen says that the total angular momentum of helium ground state of is zero.
My question is since the the Hamiltonian $H$ commutes with the total angular momentum $J$ why can we have energy eigenstate of the form $$\psi(E,J)=k(E)\phi(J)$$ such that we have
$$HK(E)=e_0k(E)$$ $$J\phi(J)=j_0\phi... |
Griffiths, problem 3.47: show that the average field inside a sphere of radius R, due to all the charge within the sphere, is $$\langle {\bf E} \rangle = - {1 \over 4 \pi \epsilon_0} {\bf p_{\tt tot}\over \rm R^3}$$
Here his solution (or at least what I’ve understood):
First of all, let us show that the average field ... |
For Einstein's equation
$$
G_{\mu \nu} + \Lambda g_{\mu \nu} = \frac{8 \pi G}{c^4} T_{\mu \nu}
$$
with $G_{\mu \nu} = R_{\mu \nu} - \frac{1}{2} R \, g_{\mu \nu}$ where $R_{\mu \nu}$ is the Ricci tensor, $R$ is the scalar curvature, $g$ is the metric tensor and $T$ is the stress-energy tensor, the weak-field approximati... |
Particles and liquid droplets below the size of 1 micrometer usually never settle down easily, and as their size decreases, it takes longer for them to settle down. Why is it like that? Does Stoke's law have anything to do with this?
|
I would like to pose a fertilicious question. Namely, there is a door and some pusher. The door is supported by, say, beams or something else; and is not connected with the other device.
Question: suppose that for the time $\tau = 0.1$ (measured in seconds), the door was punched (or hit) by the force $F = 10^7$, exerte... |
What do we exactly mean when we speak about "unification of two interactions" or say "the electromagnetic and weak interactions are unified"?
Wikipedia states that: the electromagnetic and weak interaction "appear very different at everyday low energies", i.e they are separated, while "above the unification energy, o... |
What if we modify the experiment such that both twins have a spaceship and they both do exactly the same thing on time they agreed up front?
They accelerate for 1 day the opposite direction. Then they stop accelerating and drift away from each other for 10 years (in their local time) near c. Then they simultaneously de... |
I can physically understand how kinetic energy can be converted to thermal energy. (vibration of particles)
But what's the equivalent understanding of throwing a ball up in the air, where the ball's kinetic energy decreases and it's gravitational potential energy increases because these two forms of energy are converte... |
The question is:
The angular momentum components of an atom prepared in the state $|\psi\rangle$ are measured and the following experimental probabilities are obtained:
\begin{equation} P(+\hat{z}) = 1/2, P(−\hat{z}) = 1/2,
\end{equation}
\begin{equation}
P(\hat{x}) = 3/4, P(−\hat{x}) = 1/4,
\end{equation}
\begin{equa... |
These slides show that contribution $\Delta N_{\rm eff}$ to the "effective number of neutrino species" $N_{\rm eff}$ by light relics can be computed by first noting that
\begin{equation}
g_*(T_{\nu{\rm -decoupling}}) = 2 + \frac{7}{8}(2 + 2 + 2\times 3) = \frac{43}{4}
.
\end{equation}
Using conservation of comoving ent... |
----I am a student on Quantum Computing--- For the whole undertanding of
"Tetrapartite entanglement measures of GHZ
state with uniform acceleration" by Qiang Dong. https://doi.org/10.1088/1402-4896/ab2111
I read this equation
|0>Minkowski = cos ri |0> RindlerI · |0> RindlerII + sen ri |1>
RindlerI · |1> RindlerII
|1>M... |
I am looking for some help with a problem of Electrostatics.
Let us consider three parallel conducting slabs $P_1, P_2, P_3$ of a certain surface $S$, small thickness and mutual distance $d$. We know that the potential of the central one ($P_2$) is $\varphi_0 >0$, while the other two are connected to ground, i.e. their... |
If we consider 2 linearly independent basis as follow:
$$\{ |\psi_1 \rangle , |\psi_2 \rangle ... |\psi_n \rangle\}$$
$$\{ |\phi_1 \rangle , |\phi_2 \rangle ... |\phi_n \rangle\}$$
And they are related by a unitary tranform such that:
$$U|\psi_i\rangle = |\phi_n\rangle$$
If O is an oprator in basis $\{ |\psi_1 \rangl... |
At first, this question seemed silly, but there might be some sense to it. OpenAI's GPT algorithm suggested to me that using oil in fusion technology could be a breakthrough. I thought about it for a bit, and my first thought is that the oil might combust, but the chemical combustion energy is small in comparison to ... |
The Matrix the movie regards the whole world as being binary and us living in a computer simulation.
Could the world be represented as binary similar to a matrix or is that not practical give quantum mechanics?
|
Amongst the self-consistent field methods, the practitioner solves a set of Schrödinger like equations for independent electrons. I have tried to understand what a molecular orbital is from the Wikipedia article, but I can't say what it is because I feel the explanation is so elaborate. But it sounds like it could be t... |
The basis of pulse shape discrimination is that gamma-rays and neutrons have different decay times of their electronic pulses. What makes gamma-rays and neutrons interact with the same compound interact differently such as to produce different modes of decay? For example, in zinc sulfide, heavy charged alpha particles ... |
On a rotating wheel space station crewed by humans with sea-level conditions (temperature above the freezing point), if liquid was spilled on the floor am I correct in understanding that the Coriolis Effect would cause the liquid to appear to move in the direction opposite of the direction of spin of the station?
Would... |
My question is based on the pdf in this link
On page 8, the authors consider an example of massless fermions. I follow through most of the steps in here except for equation 41, which I believe should be:
$\overline{\mathbb{\psi}} \to \overline{\mathbb{\psi}} e^{+i\frac{\vec{\tau}}{2}\vec{\Theta}}$
Then when we reach th... |
Among the four fundamental forces, it is now pretty well-known that the electromagnetic and gravitational ones travel at the speed of light.
How about the other two (strong and weak nuclear forces)? Does it even make sense to talk about their speed?
|
Consider a particle of mass $\text{m}$ fired from below into a bob of mass $\text{M}$ of a long, simple pendulum. The particle remains inside the bob and the bob rises through a height of $1.8\text{ m}$. What was the speed of the particle just before striking the bob?
I took the bob, the particle and the earth to be ... |
In classical field theory, due to Noether's theorem, corresponding to every continuous symmetry there is a conserved current/charge. However, to arrive at this conclusion one has to assume that the Euler-Lagrange EoM holds,
$$\partial_\mu\frac{\partial\mathcal{L}}{\partial \left(\partial_\mu\phi\right)}-\frac{\partial\... |
In Nakahara's derivation of the path-integral in "Geometry, Topology and Physics" the following identity is used
$$
\partial_x^n e^{ikx} = e^{ikx}(ik + \partial_x)^n\tag{1}
$$
to obtain
$$
e^{-i\epsilon[-\partial_x^2 / 2m + V(x) ]} e^{ikx} = e^{ikx} e^{-i \epsilon [-(ik+\partial_x)^2/2m + V(x)]}\tag{2}
$$
which seems ... |
According to Ch. 4.2 in Quantum Field Theory in Condensed Matter Physics by N.Nagaosa, when we deal with superfluid problem, bosonic field can be decompose into amplitude and phase:
$$\begin{array}{l}\psi(r, \tau)=[\rho(r, \tau)]^{1 / 2} \mathrm{e}^{\mathrm{i} \theta(r, \tau)} \\ \bar{\psi}(r, \tau)=[\rho(r, \tau)]^{1 ... |
I am working with the covariant derivative and trying to show that the commutator of this derivative
$[D_\mu , D_\nu]$ is proportional to the field $F_{\mu \nu}$. That is, I need the final term to
be have $(\partial_{\mu} A_{\nu}-\partial_{\nu} A_{\mu})$ contained in the answer (proportional to
the field $F_{\mu\nu}$. ... |
I am learning about center of mass these days. While doing so, I encountered the equation
$$\sum {F_{external}} = ma_{com}$$
Then, it was written that with the help of this equation, it can be clearly seen that if the blades of ceiling fan are not kept at 120° the center of mass won't be at the center of the fan and th... |
In this video, Veretasium posits that you can only measure the speed of light by assuming that its the same in different directions. He says this is just a convention (quoting Einstein). No one can ever know if its true. But then at 14:12 in the video, he mentions how looking in one direction, you'd see things in their... |
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