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I have 3 operators which are generators of $SO(2,1)$. I don't know the expressions of these operators as differential operators, but I know their action on a basis $\left|l',m\right>$:
$$J_{\mu\nu}\left|l',m\right>=\sum_{\tilde{l'},\tilde{m}}C_{\mu\nu}^{\left(l',m\right),\left(\tilde{l'},\tilde{m}\right)}\left|\tilde{l... |
I am a bit confused about what are the properties that hold for black holes in general and which ones only hold for stationary black holes. Let me try to explain what I know and hopefully people can correct me if I'm wrong.
All black holes have event horizons, which are defined as the boundary of the region from which... |
While some nonlinear crystals can convert incoming laser light into harmonics, thus for example doubling the light frequency, are there any crystals or other transparent materials that can reduce the frequency of laser light while matching the phase or maintaining a stable phase shift.
|
The below Minkowski spacetime diagram includes three worldlines, where B is the observer and has a rest frame. A and C both have a velocity of 0.71c.
I then created a second diagram where worldline A is the observer. I believe I calculated the new velocities correctly, where the velocity of A is 0c, the velocity of B ... |
(This is the first part of Polchinski's problem 1.6, here it my attempt). I have the following boundary conditions on the $X^{25}$ component being $X^{25}(\tau,0) = 0$ and $X^{25}(\tau,l) = y$ for some constant $y$. I am trying to modify the general solution for the open bosonic string given in Polchinski's equation (1... |
I'm reading the article A pure Dirac's canonical analysis for four-dimensional BF theories. But when I get to the action, written as
$$S[\text{A},\textbf{B}]=\int_M \textbf{B}^{IJ}\wedge\textbf{F}_{IJ}(A),$$
I don't know what I'm summing over (what are the $\textbf{B}^{IJ}$ and $\textbf{F}_{IJ}$ supposed to be? What do... |
The general matrix element of the electromagnetic current can be written as $$iM^ {\mu} = \left< p^\prime,s^\prime | j^\mu (x) | p,s\right>=\bar{u}(p^\prime,s^\prime)\left( R(q^2) \gamma^{\mu} + S(q^2) (p^{\prime \mu} + p^{\mu}) + P(q^2) (p^{\prime \mu} - p^{\mu}) + G(q^2) i \sigma^{\mu \nu } (p_{ \nu}^{\prime} + p_{\... |
This is in Peter Woit's book towards the end of chapter 12. We were studying green function method and applying to Schrodinger equation.
The prototypical setting is we want to solve for $\psi$ in
$$ D\psi=J$$ for $D$ the differential operator and $J$ is the source.
We defined $\psi_+(q,t)=\theta(t)\psi(q,t)$ we then ta... |
It's known that it's possible to map a 4-vector $x^\mu=(t,x,y,z)$, here i use $c=1$, into a 2x2 hermitian matrix as linear combination of Pauli matrices, thus the mapping $x^\mu \leftrightarrow X$. Where $\mathcal{H}^{2x2}$ is the set of 2x2 hermitian matrices.
$$X=t\sigma^0+x\sigma^x+y\sigma^y+z\sigma^z=\begin{pmatrix... |
The situation at hand:
We have an infinite, thin conducting, grounded ($V=0$) plate at $z=0$.
Point charge (with charge +$Q$), at $z = a$.
How exactly are the charges distributed? I used the method of images and found the surface charge density is negative everywhere at $(x,y,0)$. Where did all the positive charges g... |
I once saw the Freeman Dyson's article, referring the Expansion series occurring in Quantum Field Theory is asymptotic in nature;
It will deviate from actual physical phenomena when too many terms are used.
But I could not find formal proof for proving those expansion is asymptotic.
Is it be able to shown in answer of ... |
The classic question is "What happens to a pencil if I, standing in an elevator speeding downward, lets go of it at the exact second the elevator begins its fall?" As I understand, the pencil seems to hover in the air as it falls at the exact same rate I do. But, what happens to a pencil if I, standing in an elevator ... |
I know there have been plenty of variations of this asked before, but all of them I have seen don't really answer the question, or at least in a way that 'clicks' with me.
In terms of how i already understand it, i'll discuss by focusing on the positive charges:
Firstly, by the right hand rule, they go down initially, ... |
I was just sitting when it came to me - will a metal rod that has been kept under bright light for a very long time, be able to conduct electricity?
I was thinking that because of photoelectric effect, all of its outer shell electrons would have gained energy from the photons from the light source and would have escape... |
If a stationary mass $M$ explodes into 2 masses $m_1$ and $m_2$ with velocity $v_1 $and $v_2$ respectively releasing no energy in any other form like sound and heat.
Then I've read that-
intial k.E = Final K.E
i.e
$$0 = \frac{1}{2}m_1(v_1)^2+ \frac{1}{2}m_2(v_2)^2 $$
But i am confused that wont't the sum of final K.E w... |
I have some slight confusing in deriving the gravitation potential energy.
In the image below, it explains that the gravitation potential energy is equal to the work done from infinity to a distance r between two masses. And that the work done here will be stored as gravitational potential energy at point r.
How is thi... |
In cosmological perturbation theory, it's hard to find papers that would expose the general principle to perturb physical quantities (metric, fluid pressure and density, speed...) up to the $n$th order. Given the first and second orders I've found, it seems that the perturbation terms follow a Taylor expansion. The rea... |
I've been trying for a long time to figure out what the heck mass even IS. In introductory physics and chemistry, students are told that massive objects are those that are made of matter and take up space. But then matter is defined as anything that takes up space and has mass, which is circular. Later on, we learn ... |
I came across this question (very simple):
"A dog is running and starts to get faster at $2 ms^{-2}$ for $3s$. If the dog covers $20 m$ over this time, what velocity did it start with?"
Using the kinematic equations, the answer is $3.7 m/s$. My teacher said that this is true regardless of the nature of the object. For... |
I have two identical massess with rest mass $m_0$. One of them is made to move with very high velocity $v$, while other is at rest. At some point in time the moving mass collides with the stationary mass and gets stuck to it, now they both move as 1 body with some unknown velocity.
My Doubt-
I want to know the rest mas... |
Let's say, we have a mixed tensor of type (2,1) denoted by $T^{mn}{}_p$ and the goal is to find the expression of $[\nabla_a, \nabla_b] T^{mn}{}_p$ in terms of fundamental tensors.
Firstly, I am calculating $\nabla_a \nabla_b T^{mn}{}_p$. As we can consider $\nabla_b T^{mn}{}_p = T^{mn}{}_{p;b} = Q_b{}^{mn}{}_p$ (Is it... |
I have run into an issue while trying to prove the Holstein-Primakoff commutations
\begin{align*}
[S^+_i,S^-_j]=2 \delta_{ij} S^z_i, \ [S^z_i, S^-_j]=-\delta_{ij} S^-_i
\end{align*}
where
\begin{align*}
S^+_i&=\sqrt{2S - n_i} a_i, \\
S^-_i&=a^{\dagger}_i \sqrt{2S - n_i}, \\
S^z_i&=S - n_i, ... |
In Griffith's Introduction to Quantum Mechanics he describes the operators related to spin-$1/2$ particles in chapter 4. One of those operators is
$$
\hat{S}_z=\frac{\hbar}{2}\hat{\sigma}=\frac{\hbar}{2}\left[\begin{array}{cc}
1 & 0 \\
0 & -1
\end{array}\right],
$$
whose eigenvectors represent 'spin up' and 'spin down'... |
I'm trying to solve the following problem:
a) Consider a spring (of constant $K$) fixed on one end, $F_1$ is applied on the other such that $x=x_0\ cos(\omega t)$. What does $F_1$ have to be?
b) A force $F_2$ is applied to a body of mass $m$ so that its motion is as described by the spring in (a). What does $F_2$ hav... |
I have been thinking about how periodicity in a physical parameter is related to the discretization of its canonical conjugate, much like the periodicity in time results in the discretization of the Fourier frecuencies.
For example, the periodicity in the angle parameter results in the discretization of angular momentu... |
Why is velocity classified as a vector quantity. Can it be explained by the same way as force referring to the Phys.SE post Where am I confused about force addition?
|
So, we all know that the strong force asymptotes but the thing is I've never gotten a good description as to why
Can someone explain;
How the Strong force weakens with distance? I think I have got the least appreciable grasp on this one, can I think off it as the quarks "absorbing the gluon flux tube thus the less for... |
Why is the enthalpy of formation a function of the temperature?
We can see in the dedicated tables (such as JANAF),
that the enthalpy of formation changes with temperature.
Doesn't the enthalpy of formation stay constant, while the sensible enthalpy of a species only changes with temperature?
|
In Dale's answer to the collision rest mass problem, how is he concluding that the momentum 4-vector of the resulting particle is equal to the sum of the 4-momentums of the incoming particles. I am specifically wondering about this step in his analysis:
$$R^\mu = P^\mu + Q^\mu$$
I agree with the final answer, it just s... |
I've been perplexed by the semantics used in Science 329, 418-421(2010), where they state that according to
Born’s rule and its square exponent, interference always occurs in pairs of possibilities.
Alternatively,
Born’s rule predicts that quantum interference, as shown by a
double-slit diffraction experiment, occur... |
Suppose I have a Hamiltonian of this form :How can a Bogoliubov transformation be implemented numerically. Here, we suppose they are all bosonic operators.
$$\mathcal{H}=\sum_{\vec{k}}\begin{pmatrix}
a_{k}^{\dagger} && b_{k}^{\dagger} && a_{-k} && b_{-k}
\end{pmatrix}
\begin{pmatrix}
c && w^{*} && 0 && x^{*}\\
w && c &... |
I am trying to simulate the dynamics of a 1D Heisenberg chain using Python.
I am going step-by-step.
There is an external magnetic field along +Z direction.
At first we consider a single classical spin, oriented at some angle $\theta$ with the +Z axis. So particle's Hamiltonian is $H=-S_zB_z$.
Classical spin means, it ... |
The main limit on artillery range is drag. Hence for the same muzzle velocity, the WWII 800mm Schwerer supergun had twice the range of the modern 155mm M777 gun, because the super shell had a much greater ballistic coefficient.
Now, I want to compare two approaches to compensating for drag.
The first is increasing muzz... |
Hi I would appreciate help understanding this question, the answer is D but I do not quite understand why. It won't be B as if Friction acts in that direction it will go toward the outside of the circle. In regards to the rest of the options, I am lost.
|
It's my first question here about physics.
I would like to ask about the macro-scale physics (the governing equation) needed to implement a dynamics simulator with adhesion and cohesion. Consider the starting example illustrated by the picture below:
A harder object is suspended static under a ceiling by a thick goo o... |
Smart people, like us, poo-poo people who think of the atom as a mini solar-system with electrons orbiting the nucleus, like planets. We talk about smeared out probability waves etc.
But, given wave-particle duality, isn't the concept of an electron in orbit just as valid as the electron as a wave? Obviously the elec... |
I'm looking for a proof as to why the Hamiltonian operator's eigenvalues in quantum mechanics are the permitted energies of a quantum particle. I am looking for an intuitive explanation as well as a mathematical proof, preferably in the form of spinor notation.
|
If my understanding is right, the total wave function of any system containing electrons and protons (and any other fermions for that matter) must be antisymmetric under exchange of the respective fermion. Consequently, the total wave function of the $H_2$
molecule must be antisymmetric under exchange of its electrons ... |
I recently got interested in foundational aspects of quantum mechanics and I have some questions:
Bell's theorem proves that any local, deterministic theory with statistical independence can't account for certain observed correlations. The standard QM formulation is usually considered local, with no determinism, but I ... |
In the context of a Klein-Gordon field with charge $e$, mass $m$, immersed in an external classical electric field $A_\mu = (A_0(z), 0)$, I am asked to calculate the charge density of the field solution to the 1+1 dimensional Klein-Gordon Equation
$$(D_\mu D^\mu + m) \phi (t, z) = 0,$$
with $D_\mu = \partial_\mu + ie A... |
I have been hearing lately that Black holes could be Quantum Computers or that some processes in a black hole simulate the operation of Quantum Computers. This is not my field of study, but I am looking to explore the subject in more detail. Any reading materials in the area that you can share with me would be great.
|
In Weinberg's Gravitation and Cosmology, on page 165 he notes that $h_{\mu \nu}$ is lowered and raised with the $\eta$'s since unlike $R_{\mu\kappa}$ it is not a true tensor (or at least implies it). I may be misreading this but isn't this not true as $h$ is indeed a tensor since it transforms as one? Is this simply fo... |
In the following question (no longer homework):
A basket of negligible weight hangs from a vertical spring scale of force constant 1500 N per m. a) If you suddenly put a 3.00 kg adobe brick in the basket, find the maximum distance that the spring will stretch. b) If, instead, you release the brick from 1.00 m above the... |
To an observer traveling towards the Earth at a relative velocity close to c, the Earth will be thinner than it would be to a stationary observer, due to length contraction.
What happens as the relative velocity gets so close to the speed of light that the Earth appears thinner than an atom? Thinner than an attometer? ... |
It can be read almost everywhere that plasma is the best convertor of transverse waves to longitudinal waves.
I'm not much interested in the theory here. Rather, I would like to know how to do it in a practical way.
So, assume I have a big plasma tube, and a 1GHz - 10GHz horn antenna. Assume furthermore, if necessary, ... |
Last night I posted this question: Since light has inertia and experiences gravity, what does it mean for photons to be massless?, which I now think was overly wordy and didn't properly express what I actually want to know. But I don't want to change the meaning of that post since it's already gotten answers, so this ... |
On the one hand, the cathode ray experiment conducted by JJ Thomson seems to indicate that the radius of path deflection of an electron beam is also governed by the same centripetal force equation that describes large, macroscopic objects ($\frac{mv^2}{r}$). In addition the electron beam has a defined curvilinear motio... |
Third law of thermodynamics says that it is impossible to reach absolute zero temperature in finite numbers of operations. According to quantum mechanics, every system has energy levels and ground state. Is it possible according to quantum mechanics that any system would reach ground state in finite time by photon emis... |
I am trying to understand Section 3.8.3, "Independent particles", of Piers Coleman's Introduction to Many-Body Physics (self-study, mathematics background). He considers "a system of independent particles with many energy levels $E_\lambda$," with Hamiltonian
$$H - \mu N = \sum_{\lambda} (E_\lambda - \mu) \hat{n}_\lamb... |
It is often claimed in quantum field theory texts that to have a sensible Lorentz invariant theory, the fields introduced must be in representations of the Lorentz group. This fact has always seemed obvious to me until recently when I pondered on it and realised I couldn't convince myself of it.
For example, I could de... |
In Fleming's left hand rule, we can see that if current is in direction of middle finger and magnetic field in the direction of fore finger, the thrust must act on the direction of the thumb. These three are mutually perpendicular. But isnt the opposite direction of the thumb is also perpendicular to remaining both of ... |
Since surface area of the remnant black hole must be more that the sum of the binary surface then the maximum energy released via gravitational waves is
$$
ΔE = [M_1 + M_2 – \sqrt{M_1^2 + M_2^2}]c^2
$$
That means that when ratio of the initial masses is very large then almost all mass of smaller black hole may turn int... |
I am struggling to understand the following computation from page 59 of Tong's QFT notes
http://www.damtp.cam.ac.uk/user/tong/qft.html
The expression
$$
(-ig)^{2} \int \frac{d^{4}k}{(2\pi)^{4}} \frac{i(2\pi)^{8}}{k^{2} - m^{2} + i\epsilon} [\delta^{4}(p'_{1}-p_{1} + k)\delta^{4}(p'_{2}-p_{2} - k) \\ \hspace{50mm} + \de... |
What is the meaning of the real and imaginary parts of the optical Hall conductivity and also the interpretation of the negative Hall conductivity?
|
The first law of motion states that :
"Every body continues in its state of rest, or of uniform motion in a
straight line, unless it is compelled to change that state by forces
impressed upon it."
Now consider a body with initial mass $m_{0}$ that constantly changes with respect to time. If the net force acting on ... |
I am trying to generate a piano noise by a python function.
def piano(phi):
amps = [...spectrum information...]
psi = phi
result = 0
for a in amps:
result += a*numpy.sin(psi)
psi += phi
But I can't find anything helpful to fill my spectrum list. Can someone help me with that.
|
I'm currently reading David Tong's lecture on Statistical Physics, and I cannot understand the logic in the following paragraph about the low temperature expansion of 2d Ising model.
It can be obtained by diagrammatic calculation that $Z = 2 e^{2N\beta J} \left(1 + N e^{-8 \beta J} + 2N e^{-12 \beta J} + \frac{1}{2} ... |
If you have a number with a dimensional quantity in its exponent, what is the dimensionality of this number then? For example when you have $e^{(4J)}$ or $2^{(4N)}$, with $J$ and $N$ respectively Joules and Newton.
I know that you can't take the logarithm of a dimensional quantity, but I don't really understand the cas... |
I'm currently studying statistical mechanics and having a hard time going conceptually from the canonical ensemble to the gran canonical ensemble. Up until now I've been studying only ensembles with a fixed number of particles therefore I've been thinking about the system's state as living in a 6N-dimentional phase spa... |
A curve $L$ is a geodesic iff the tangent vector field $v$ associated with any parametrization of $L$ obeys
$$\nabla_{v}v=\kappa v$$
where $κ$ is a scalar field along $L $.
A vector field $v$ obeying the above equation is called a pre-geodesic vector field. The scalar field κ is then
called the non-affinity coefficient... |
Let's say a very small asteroid, the mass of 12 500 kg is orbiting the Sun at the distance of exactly 2 AU and the velocity 19 700 m/s. If needed - it is going 49 degrees from the general direction of left, the angle is facing downwards, and looking right above the orbital plane. Is it possible to calculate the eccentr... |
I'm currently studying QFT and QCD for the first time and I have a question about the colour charge indices given below. I was asked the following question:
(a) Derive the Feynman rule for the 3-gluon vertex $V\left[A_{\mu_1}^{a_1}\left(p_1\right), A_{\mu_2}^{a_2}\left(p_2\right), A_{\mu_3}^{a_3}\left(p_3\right)\right... |
Since the thermodynamic arrow of time is related to the second law of thermodynamics, how can I (mathematically) describe the operation of the operator $\hat{T}:t \mapsto -t$ on said law ? In other words, how to generally mathematically describe the effect of a reversal of time on the second law of thermodynamics ?
|
Since perpetual motion refers to a never-ending motion with no external energy provided whatsoever, can land breezes or sea breezes be an example? Or perhaps even trade winds, since this, I believe, is a pattern that keeps going due to natural convection and the Coriolis effect, right?
I do know perpetual motion is mor... |
As for (a), I easily derived that $\mathbf {E}_2 = \mathbf E_1$ at the 'boundary' of the intersection plane. However, how do I know the rest of the second region? The solution states rest of the region is also same as the one derived at the 'boundary', but I don't understand the exact logic.
|
As there is no drag in space/vacuum, is it possible to actually send a probe with enough fuel to have it achieve the speed of light or a value very near to it? Since there are not many significant forces that can slow down the speed (also why planetary motion will still continue for billions of years, I suppose) I am a... |
Can a magnet (or a current-carrying conductor) lose its magnetic energy through moving electrons? How does the energy conversion happen?
|
Equivalence principle tells us that for a freely falling inertial observer spacetime is locally flat. The coordinate transformation needed to introduce Locally Inertial Coordinates were discusses in this response. However, I have studied in general relativity that no coordinate system is globally inertial and so there ... |
If I strike an object with mass $1$ kg with a force of $1$ N (let's say in space), would that object continue to travel in space with an acceleration of $1$ $m/s^2$? My intuition suggests that it would continue travelling at some constant velocity. If it were accelerating, where would it get the energy to keep going fa... |
When we try to prove that if Clausius statement violated then KP is also violated we assume that that cold source gives the same amount of heat as it receives. My question is: How is this proof generally true, doesn't this work only in this specific case? What if the cold source receives more heat than it gives, would... |
I read the following on the internet:
"This means that as sound travels, its relative frequency content alters making the low frequencies more prominent at greater distances, creating low frequency noise problems. As a result of this it is not uncommon for complaints to be received from residences located far away from... |
Show that if there are $M$ independent constraints $\phi_m(x_\mu,p_\mu)$ there are $M$ of the $\ddot{x}_i$'s that the Euler-Lagrange equations cannot be solved for.
Attempt of solution:
Assume that we are in a $d$-dimensional spacetime (i.e. $\mu = 0,...,d-1$) and $m=1,...,M$.
Define $M_{\mu\nu}:=\frac{\partial^2\mat... |
A circular loop carrying current "I" in anti-clockwise direction is placed between two straight and parallel wires each carrying current I. Ignoring the force of the straight wires on each other, where is the circular loop attracted towards?
I've been struggling with this question and need some conceptual help. Firs... |
My question surrounds the time it takes to see a star and it's ending. OK, a star is 100 light years away, so it takes 100 years to see the light from it when that star 1st begins sending light. 100 years. For simplicity purposes, lets say I saw that star for 100 of my years, so it has lasted at least for 100 years. Th... |
In the PBR-Theorem they try to prove that $\psi$-epistemic models of quantum theory are impossible. The argument goes something like this:
Suppose we have two nonorthogonal states
\begin{equation}|\psi\rangle=|\uparrow\rangle \text{ and } |\phi\rangle=|+\rangle=\frac{1}{\sqrt{2}}(|\uparrow\rangle+|\downarrow\rangle) ... |
I have been researching ion traps (of singular atoms) recently and have become curious about neutral atom trapping and in particular if it is possible to trap neutral atoms while they are "hot". Furthermore, I wonder if it is possible that a "hot" ion/atom (neutral) could be trapped in a small volume while still being ... |
A stationary observer observes a rotating disc with radius 1 at angular velocy w. Let's say this disc is centered at origin in xy plane (all angular Velocity mentioned in this question is around the origin).
The stationary observer also obeserved a different observer M walking with velocity v in the plane z = k and cro... |
I had a question regarding gravitational potential energy and escape velocity. I don't really understand the concept of escape velocity. I have been learning it as the velocity required for an object to never come back to the planet, however, I don't understand how this works. Theoretically will it just keep moving for... |
Question is fairly straight to the point. In particular, how does it influence the strength of particle interactions?
|
The formula for the Electric field strength (magnitude) is:
$$E=kq/r^2$$
where $k$ is a constant, $r$ is the distance from a point charge, and $q$ is the magnitude of the point charge. Given this there would be a singularity at $r=0$. How is this handled? A singularity would occur for any power of $r$ in the denominat... |
https://www.youtube.com/shorts/Kgs9_3UH3Pk
In this video, a pendulum is formed from a paint can full of paint with a hole in the bottom. The pendulum's swing traces out an ellipse that slowly rotates and narrows as the paint leaks out onto the canvas. Why does the ellipse rotate like this?
|
I am confused about one derivation of the gravitational time dilation.
Consider a one dimensional time-independent gravitational field. Two clocks are at rest with respect to the gravitational field and located at positions $h_1$ and $h_2$ respectively. Release a third clock with an initial speed $v_1$ at $h_1$ free fa... |
Given a N-particle system, with Hamiltonian operator equal to ${H}_N$. I'm interested in studying the limit N to infinity of the average of the hamiltonian over a set of states $\psi_{N}$. Is it necessary to have a constant $C$ such that the average of the hamiltonian over the state $\psi_{N} $ is bounded by $C N$ to s... |
I am reading this paper which is about dye sensitized solar cell, but I do not understand its statement about the open circuit voltage of the cell (page 2242):
In page 2242, the paper says that:
The voltage generated under illumination corresponds to the difference between the Fermi level of theelectron in the $\rm T... |
I have attempted to derive Eq. (16.9) in Landau/Lishitz' "Mechanics", 3e. If someone could let me know if my derivation is on the right track, it would be greatly appreciated. I do hope that this question won't be closed as a "check-my-work" question, as L+L are notorious for sweeping details under the rug, but I under... |
Spallation is an overloaded term and most articles discuss other forms of it (such as nuclear spallation or meteor impact) than the type that I would like to learn about.
I'm interested in spallation that occurs in a high-vacuum environment when a fast moving molecule glances off of a smooth hard surface. My concern is... |
I recently watched this video https://youtu.be/Wsjgtp9XZxo?si=sIRlAbvAm2wjXRNP
and tried (unsuccessfully, because i don’t have the knowledge required) to read Bruckner’s paper.
What i am missing, is the reason why Hossenfelder is saying that we need a big enough apparatus to cause decoherence in order to make a measur... |
Background material:
These are the parts that I can follow.
Previously Peskin & Schroeder have derived already the expression of the interaction ground state $|\Omega\rangle$ in terms of the free vacuum state $|0\rangle$:
$$|\Omega\rangle=\lim_{T\to \infty(1-i\epsilon)}\left(e^{-iE_0T}\langle\Omega|0\rangle\right)^{-1}... |
I was reading this article and got to the part where the homogeneity of space and time leads to the linearity of the transformations between inertial frames.
In particular, the function $x^\prime=X(x,t)$ is shown to have the property $$\left.\frac{\partial X}{\partial x}\right|_{x_2} = \left.\frac{\partial X}{\partial ... |
This question is pretty much what I am confused about. However, the answer says that we require local phase symmetry to keep the lagrangian gauge invariant. As far as I can see the argument only works the other way around, i.e. we impose gauge transformation to make the local symmetry work. We can couple the EM field t... |
In a talk given by Spekkens (Why I Am Not a Psi-ontologist) at 4:00 he talks about an assumption called $\lambda$-sufficiency which is part of any no-go theorem of quantum mechanics. It is described as stating "Once an ontic state is specified, its response to experimental probes is often assumed to be independent of t... |
I tried to answer the following homework problem:
I managed to answer the problem after some thinking, but I want to know the FBD of the pulleys. In a typical Atwood's Machine Problem, the two strings would be parallel to a vertical axis, and there would be two tensions exerted on the pulley at the two points of conta... |
When both the distances $R$ and $f$ are measured from mirror only they shouldn't be of sm sign? When we take it negative in mirror formula that I understood... But why here I'm confused
|
According to Amperes law the integral of the magnetic field $B$ dotted with the $dl$ along a closed loop is proportional to the current passing through the surface area of any shape given by the closed loop path, so my question is why doesn't a magnet stationary in a coil continuously create a current, this seems to go... |
I have a question regarding an old exam (quantum at undergraduate level) question that I never fully understood. We have a Hamiltonian
$$H= E\begin{pmatrix}
0 & 1 & 1\\
1 & 0 & 1 \\
1 & 1 & 0
\end{pmatrix}$$
That supposedly models a single electron in cyclopropane molecule that we were told to assume was an equilater... |
I have found a paper(See this) which talks about the comparison of classically correlated source and an entangled photon source (generated by Spontaneous Parametric Down Conversion)for ghost imaging. I've found that classically correlated source can be used for ghost imaging but an entangled photon source provides much... |
If I imagine a photon being released from the plate below as soon as the plates start moving, shouldn't the photon hit the opposite plate a bit behind the point where it would have hit if the plates were stationary, how does the photon move with the two plates?
|
This is motivated by this post Metropolis-Hastings and underlying Markov process. I am also trying to compute the stationary state of the Boltzman distribution by the method discussed in the post. Here, I am considering three states A, B and c with energies $-1, 0, 1$ respectively. For matrix G, I am assuming every sta... |
I would like to know about any research that is conducted to get spectral lines in the gamma range of gamma-ray burst. I try to find data or information about these typical spectral lines. Is it possible that absorption lines in the spectrum of a star or gamma ray burst which occur at different wavelength (up to the ga... |
A Yang-Mills theory can be constructed for any Lie group that is compact and semisimple. The motivation behind this is discussed in this question. Is there any physical reason we choose $SU(3)$ or $U(1)$ for QCD and QED respectively? I am still learning about Yang-Mills theory, but so far I get the impression that thes... |
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