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For hydrogen, we use $[Q,P]=i\hbar$ for electron, which is a fermion. Does it have a deeper reason such as that we're really considering the proton + electron system, which might be of bosonic nature?
|
Showed in this paper, the Weyl double copy relates exact solutions in general relativity to exact solutions in gauge theory, formulated in the spinorial language. The relation can be expressed as $\Psi_{ABCD}=\frac{1}{S}f_{(AB}f_{CD)}$, wher $\Psi_{ABCD}$ is Weyl tensor of the curve spacetime and $f_{AB}$ is Maxwell te... |
I am a grade 12 student conducting a physics experiment on Bernoulli's principle and the coanda effect. In the experiment set-up shown here, a sphere made of Styrofoam is suspended in the air next to the tap. When the tap is turned on, the sphere gets 'attracted' towards the jet stream and the water starts to flow alon... |
Thermal conductivity is a property normally related to material. But it is also possible to relate it to objects.
Consider two objects of different shapes made by the same homogeneous material. How can I calculate the effective thermal conductivity of them using their mass distribution and their mass-moment tensors? Fo... |
Please consider the following situation (ignoring air friction, and assuming all strings have no mass):
Ball A with mass m1 is hanging from the ceiling by the blue string.
Ball B with mass m2 is hanging by another string, from ball B. So currently, the system is at rest.
Now, somebody cuts the blue string.
Which of the... |
I'm trying to create a workflow where one step of the process is taking in a primitive cell of a crystal structure and produce a cell that has the highest possible symmetry (conventinal cell) automatically. For example, if I were to provide the primitive cell of the BCC crystal structure with appropriate basis, I would... |
If we heated two identical metal rod both vertically and horizontally, we would observe that it expands. However, if the rod is placed vertically, gravity will indeed play a role. The expansion of the rod increases its height, which in turn increases its gravitational potential energy. This is because the center of mas... |
I would like to ask something, which I would expect to have the same answer as the one to my previous question. But I'd like to be sure and further my understanding: A mass is hanging by a thread from another mass, which starts to fall. What happens and why?
So please consider the following situation: Car A and car B a... |
Maybe this is just a me-thing but I found when I run in snowy conditions I do not slip or fall unless I hit an unknown patch of ice. However, when I walk, I'm more likely to slip in general. Looking for answers on this I don't see any explanation come up for this phenomena.
Is there something involving running that mak... |
I was solving the geodesics of $$ds^2=dr^2+r^2d\phi^2$$ for an exercise. Using as an affine parameter the coordinate $\phi$ I arrived at the equations:
$\frac{d^2r}{d\phi^2}-r=0$
$\frac{1}{r}\frac{dr}{d\phi}=0$
One of them gives out hypebrbolics while the other gives a constant function. In the execise I am hinted at... |
The reduced Planck constant $\hbar$ occurs in multiple places in physics. For example, the spin operator of a spin-$\frac12$ particle is given by $$\bf{J}=\frac{\hbar}{2}\bf{\sigma}$$ where $\bf{\sigma}$ is a vector of dimensionless matrices. Also, the Schrödinger equation states that $$i\hbar \frac{\delta}{\delta t}|\... |
Can we make an analogy, in the narrow sense, between potential (gravitational) energy and a thermodynamic potential (eg: free energy or Gibbs potential)? Specifically, if an object of mass $m$ is at height $h$ and falls freely in a gravitational field, it tends towards the state of minimum potential energy. When the bo... |
Gauss' law states that the electric field flux through a closed surface without any charges on the inside is zero. In introductory physics, it is stated that this is true for both fields generated from within the surface and those fields whose sources are external to the surface. Examples of external fields are given, ... |
My understanding is that current is constant throughout the circuit. So it means that in the areas with high resistivity or small cross-sectional area the drift speed on electrons is the highest. Draft speed is proportional to the strength of the electric field, so the electric field is the strongest in the areas with ... |
I am looking at how to derive the Thermodynamic free energy expressions, e.g. the Gibbs free energy or the Maximum work but from a variational principle.
In analytical mechanics we can transform a problem from a classical mechanics one to a problem in differential geometry. We are imaging the mechanical system to be a ... |
In 2D simulations using Large Eddy Simulation (LES) methodology, Favre averaging is commonly applied to the variables involved in the Navier-Stokes equations, resulting in:
\begin{align}\label{aq}
\frac{\partial (\overline{\rho} \tilde{u}_1)}{\partial t} + \frac{\partial (\overline{\rho} \tilde{u}_1\tilde{u}_1)}{\p... |
I have a question on adding dissipation into the Lagrangian. On this page:
https://profoundphysics.com/friction-in-lagrangian-mechanics/ the approach with adding an exponential factor to the Lagrangian is descibed.
Starting with a lagrangian $L(\dot{q},q) = T(\dot{q}) - V(q)$, one can add an exponential damping factor:... |
So, I came across this problem:
A skier goes from position A to position B, and then in B, rises again.
What must be the height ($h$) for the skier to reach B with double the velocity.
I can't seem to be able to figure this out.
(Ignore non-conservative forces)
Here's what I tried:
I tried to find the relationship bet... |
It is known that all particles follow a geodesic in spacetime. Presumably gravitons follow geodesics as well. However, how does one describe that mathematically? For the case of other particles it is more straight forward as their energy-momentum tensor would couple to the metric. The case of graviton seems to be more ... |
I'm having a hard time differing between the Christoffel symbols and the Riemann tensor.
I know their formulas and their uses but i'm searching for a physical interpretation on the general theory of relativity.
While i know that mathematically, Christoffel symbols have more to do with the connection and the Riemann ten... |
I am deeply fascinated by the apparent intrinsic relationship between harmonic frequencies and the natural world. This relationship is evident not only in the mathematics that simplify our description of the universe but also in the very phenomena that resonate with these frequencies. My curiosity compels me to explore... |
I've avoided the use of the word "force" here, because I think that's not the right model, but correct me if I'm wrong. In describing a wave, the wave has peaks and troughs of equal distance, ceteris paribus - what is the limiting circumstance that causes the wave to return to the baseline from either direction, instea... |
I'm studying the behavior of a two-dimensional electron gas in a magnetic field, focusing on the quantization of wave vectors and the resulting energy levels, specifically Landau levels. However, I've come across a point of confusion regarding the application of boundary conditions and the consequent quantization of th... |
Can a hydrogen atom be converted to a neutron with a sufficiently high energy photon? Or perhaps via a pair of photons having total energy of about 800 keV? One photon would have an energy of say 430 keV and the other about 370 keV. The 60 keV difference would give a wavelength roughly equal to the diameter of the h... |
I am looking for references or articles that apply or explain how to apply the dimensional reduction method to known metrics such as Minkowski, Schwarzschild, Kerr, etc. The references I found generally do so in a general way and I can't quite assimilate what happens in more particular or simple cases. Could someone pl... |
I have heard matter defined as energy within a closed system and that any such closed system will have mass.
Is this correct?
|
There are bug swatter racket that can kill fruit flies, mosquitos, or flies, if the insect touches the metal mesh.
However, when I look at the construction of the device, the metal mesh is all one piece, meaning it is all coneected.
We heard from physics class before: if a bird stands on a power transmission line, no m... |
As known, there is an ambiguity on the definition of the stress tensor (or energy-momentum tensor).
The canonical stress tensor, defined as the Noether's current corresponding to space-time translational invariance, is $T^{\mu\nu}_{can.}=\partial\mathcal L/\partial(\partial_\mu \phi_l)\partial^\nu\phi_l-g^{\mu\nu}\math... |
In this question, I would like to consider 3 scenarios: 1) Fluid of uniform viscosity between 2 parallel flat plates with linear velocity profile, 2) 2 different fluids with different viscosities between 2 parallel flat plates, with linear velocity profiles within each layer of fluid, and 3) fluid of uniform viscosity ... |
I'm trying to numerically evolve the Einstein-Boltzmann equations for cold dark matter perturbations using Runge-Kutta method of the fourth order.
There are 5 standard equations:
\begin{align}
\dot{\Theta}_{r,0}+k\Theta_{r,1}&=-\dot{\Phi} \\
\dot{\Theta}_{r,1}+\frac{k}{3}\Theta_{r,0} & =\frac{-k}{3}\Phi \\
\dot{\delta}... |
I want to calculate the gravitational force $F$ between a point mass $m$ and another mass $m_0=m_1+m_2$ composed of two point masses $m_1$ and $m_2$ at distances $d_1$ and $d_2$ to $m$, respectively. Here the space is assumed to be 1-dimensional for simplicity. First, $F$ can be found by superposition: $F=F_1+F_2=Gm (m... |
I was recently given a little badge thing to wear to celebrate some event. The badge can be fastened to my shirt using a little magnet. The badge and magnet have since become a little fidget toy for when I am reading something at my desk.
The magnet is composed of 2 parts that (prior to my fidgeting) were glued togethe... |
This is hypothetical question: imagine a tall skyscraper says 1000m tall is lifted by a nign indestructible cables attached only at the top of the building. When the cable is released what happens? Would I immediately see the building starts falling or it will stay at the same height for a brief period of time before f... |
When reading engineering books they sometimes use twists vs standard homogenous coordinates or quaternions.
What value is there in using twists?
|
Can you refer some good papers to read on quantum field vortices, and a comparison with classical field vortices?
|
I recently read that when ice freezes to form hexagonal crystals, the space within the hexagon is in fact a vacuum. Could this space potentially be used to store burnable hydrogen gas? If so, would the hydrogen be released as the ice melts, or could it be extracted in some other way?
Edit: Per PM 2Ring and John Rennie'... |
I can readily accept the theory that the universe is expanding as a mathematical model to explain the fact that all galaxies are moving away from each other, but I have difficulty understanding intuitively how the space itself can physically expand. How can one tell the difference between these two scenarios:
the spac... |
We see this interesting phenomenon with water bottles in cold chillers left undisturbed for a long time; the water within remains a liquid, but a small kinetic shock, such as a tap, shake or pour, causes the water to freeze rapidly before our eyes.
A friend of mine wanted to know; is this phenomenon possible with water... |
I know some of the better known Pauli Matrix identities. But I don't know (nor could I not figure out or find online) any that could be used for the following expression:
$(\sigma_k)_{\alpha \gamma}(\sigma_j)_{\theta \beta} - (\sigma_j)_{\alpha \gamma}(\sigma_k)_{\theta \beta} = \ ? $
Does anyone know of such an identi... |
It may be a silly question but I don't see why all the drawings in the books represent the scattering
Will I have made a mistake if I represented the scattering in this way ?
It should be the same thing, I mean theta is aribitrary right?
Or is it wrong in the second picture cause the particles go "backwards" ?
|
Antimatter isn't bound by anti-energy, so doesn't that mean that even if elementary antimatter particles had negative mass, the total mass of an anti-atom would still be overwhelmingly positive?
|
I am reading an article on introduction to string theory.
Consider an open string of length $L$, rotating around its center of mass with angular velocity $\omega$. Here we fix the gauge by the static gauge $\eta_\mu X^\mu = \tau$, where $\eta_\mu= (1,0,\cdots, 0)$. It claims that,
"under the static gauge, the time-dep... |
In the famous Schrödinger's cat thought experiment, the cat is proposed to exist in a superposition of alive and dead states until observed.
A radioactive atom's decay triggers the release of a poison that determines the cat's fate.
Is the radioactive decay an essential component for obtaining a superposition, or could... |
In the current model of the big bang there is a short phase of some minutes, where all the light in the universe was trapped. Which mechanisms were able to disable the expansion of light in this phase? Did neutrinos play a part in this, even though they do not interact with light?
|
On reading Chapter 1-2 (Thermal Radiation) of Quantum Physics of atoms, molecules, solids, nuclei and particles by Robert Eiberg and Robert Resnick
It stated that
The details of the spectrum are almost independent of the particular material of which a body is composed, but they depend strongly on the temperature.
Fur... |
My textbook states the following:
$$W_{net}=W_{non−conservative}+W_{conservative}$$
$$W_{non−conservative}=ΔKE+ΔPE$$
$$W_{conservative}=−ΔPE$$
$$W_{net}=ΔKE$$
$$W=FDcos(Θ)$$
However, my teacher states that
$$W=ΔE=ΔUg+ΔU_{spring}+ΔKE+ΔE_{thermal}$$
Which I think can be rewritten as:
$$W=ΔPE+ΔKE+ΔE_{thermal}$$
But I'm at... |
I found this question in a book asking for voltage $X$. I allowed them to use any method they want. I too after revision using kirchoff's loop rules am getting too different answers. Please help me to know where I am going wrong.
|
In eq. (13.6.8) at page 558 of the first volume of the Quantum Theory of Fields by Weinberg, the following identity is given:
\begin{align}
\left[\frac{1}{(q_1\cdot p +i \varepsilon)((q_1+q_2)\cdot p +i \varepsilon)...((q_1+...+q_{N-1})\cdot p +i \varepsilon)}+\text{permutations}\right]\delta((q_1+...+q_N)\cdot p)=(2\p... |
I'm reading the lecture notes of David Tong on Statistical Field Theory, specifically chapter $4.4$ on the Kosterlitz-Thouless Transition. He considers the XY model in $d=2$ dimensions and states the following:
In the high temperature phase, we work with the complex field. The free energy
has a quadratic term $\mu^2$ a... |
I found this question, for which the answers I did not understand:
Does a charged particle accelerating in a gravitational field radiate?
So I want to dumb it down.
From my backyard, can I see photons emitted by charged particles bent by Earth's gravitational field?
What about the folks in ISS? Can they see it?
What... |
When forming an n channel in an N mosfet, do the pn junctions of the drain-substrate and source-substrate parts disappear?
Here's what I expected:
When gate voltage (higher than threshold voltage) applied, free electrons will be attracted into substrate-oxide interface.
The source-substrate and drain-substrate portio... |
Scenario 1:
There is a block on a horizontal table on which I'm applying a force of 10N.
Scenario 2:
Block B has mass m and block A has mass 3m. Tension in cord CD while B is sliding down A is $\frac{mg}2$sin$2\theta$.
In the first scenario, the vertical component of the force is zero because cos$\frac{π}2$ is zero. ... |
In my question I'm neglecting the impact of discharging.
I'm trying to make sense of Watt's law: $$P=IV.$$ I always thought that the voltage and the power of a battery were constant features that reflected the strength of the chemical forces inside the battery. As for the current, I thought that it was determined by th... |
There are not any free and independent quark in the nature. Collision of many particles inside most powerful accelerators could not produced any free and independent quark but result of collision between protons are leptons (muons)and energy but not free quarks.
|
I'm trying to make sense of transformers.
$\varepsilon_{p} = $ emf in primary coil, $\varepsilon_{s} = $ induced emf in secondary coil, $N_{p} = $ number of turns in primary coil, $N_{s} = $ number of turns in secondary coil, $\frac{d \phi}{d t} = $ change of magnetic flux.
The first thing that confuses me is derivatio... |
I have an already moving object A trying to intercept a moving target B in 3D space, and I have limited acceleration (for example not necessarily enough fuel for the optimal acceleration).
A is located at A0 in the image at time t0, and is currently traveling with a velocity va. B is located at B0, and is traveling wi... |
So, when using AU/year units, it turns out that 3rd Kepler Law: $\frac{r^3}{T^2}=\frac{G*M_{sun}}{4\pi^2}=1$, meaning $G*M_{sun}=4\pi^2$, any easy explanation for this? Cheers.
|
Generally speaking, the "sum over world-sheets" in string theory involves summing over all possible topologies of compact, orientable and connected, as Polchinski says in page $100$ of his first volume. However, to calculate $S$-matrix elements one consider a scattering amplitude of $n$ strings coming from infinity, in... |
My coworker makes rubber band balls by wrapping rubber bands one over another. At the initial stage it was pretty bouncy. Now, as it has become larger and denser, it seems to have lost its bounciness. Could anyone give me a simple physics based explanation? I have a hunch it has to do with both increasing weight as wel... |
I have been unable to find an example of a Carnot engine implemented practically, beyond the drinking bird (which has not revolutionized technology as far as I know). I understand the Stirling and Rankine engines work with similar cycles, but can a real-life model be made and implemented using Carnot cycles?
There may ... |
Consider a quantum computer, and one specific qubit $q$ in it. With the computer, we perform a series of operations which manipulate the qubits including $q$. I am interested in the time interval between two operations. Because of noise, the wavefunction of $q$ should change with time. The state at the beginning of the... |
vibrating the atom good| heat bad|fast-moving vehicle bad| one-meter cube with different atoms trying to accelerate its whole molecular structure with EM wave pulses but not cause heating damage
|
I'm asking if the electric force is quantum, and I'm not referring to photons, which I understand is quantized. Unless of course, the answer is that the electric force is only felt upon absorption of a photon, which then answers the question as well.
I'm wondering if there is a distance from a charged particle where t... |
I am trying to follow Witten’s article as much as I can.
What every physicist should know about string theory. Physics Today 68 (11), 38–43 (2015); my knowledge is very basic GR and QFT. I am really lost at one of his steps early in the article.
As I understand it, he writes an action with variable metric and free mass... |
I'm reading Quantum Mechanics by Griffiths. In the solution to one of the problems in this book they claimed that if the time-independent wavefunction $\psi$ solves $-\frac{\hbar}{2m}\frac{\partial^2\psi}{\partial x^2}+V\psi=E\psi$, then $\psi^{*}$ also satisfies the differential equation. I don't see why this is true.... |
I've been watching a lot of Graham Hancock videos of late, thrusting myself deep into the rabbit hole of pseudoarchaeology/alternative archaeology, and I don't really know enough to assess the validity of his claims...
He has claimed that at the end of the last ice age, huge amounts of water (stored in lakes on the 2 m... |
I see that the retarded/causal Green's function for the 1+1D wave equation is
$$ G(x, t \,|\, x_{0}=0, t_{0}=0) = \frac{1}{2c} H(t - |x/c|), $$
(where $H$ is the Heaviside step function) which satisfies
$$ \partial_{t}^{2}G - c^{2}\partial_{x}^{2}G = \delta(x)\delta(t). $$
I understand how to derive this result mathema... |
I'm reading the LSZ reduction formula in the wikipedia:
https://en.wikipedia.org/wiki/LSZ_reduction_formula
To make the argument simple, let $$\mathcal{L}=\frac{1}{2}(\partial \varphi)^2 - \frac{1}{2}m_0^2 \varphi^2 - \frac{1}{4!}\lambda \varphi^4,$$ where $m_0$ is the bare mass.
Let $m$ be the physical mass and $x = (... |
After extensive research, I've discovered that accurately determining the emission wavelength of quantum dots (QDs) requires understanding several key factors. As highlighted in the book "Introduction to Nanoscience and Nanomaterials," (here) two crucial elements are the energy gap of the bulk material and the reduced ... |
I'm running into some issues with the deriving Bogoliubov transformation. Specifically, in order to diagonalize the Hamiltonian
$$\begin{align}H = \sum_p \frac{p^2}{2m} \hat a^\dagger_p \hat a_p + \frac{1}{2V}\Big[ U_0 N_0^2 + 4 N_0 U_0 \sum_{p\neq 0} \hat a^\dagger_p \hat a_p + N_0 U_0 \sum_{p\neq 0}(\hat a^\dagger_p... |
We are developing a mobile system for optical coherence tomography based on fiber optic Michelson interferometer. We are facing a problem of chenging the polarization during a movement of the fiber. As I understand we need to plug two polarization controllers in base arm and in measurement arm. Is it a best idea? And w... |
The most attractive description of the double slit experiment for me is that in Beltrametti and Cassinelli's book.$^{[1]}$ The essence of their description is the following.
Beltrametti-Cassinelli description of the double-slit experiment - They somehow treat the $x$ position classically and suppose that the time of t... |
According to Einstein’s theory of relativity, any particle traveling at the speed of light experiences no passage of time. It follows that if a photon travels through space then within any two points of its trajectory the proper elapse of time for the photon is zero, which means that the photon is in all the points of ... |
I have a vessel of fixed volume with adiabatic boundary which is initially filled with air at pressure of 1 atm and temperature of 300 K. Now, I inject air from an external source at a fixed flow rate for a certain duration. The injection flow rate and duration are known to me. The injected air is also at 300 K. After ... |
In the picture Below, I was asked to Calculate the force due to surface tension on the left side of the water about an imaginary square ABCD by the right side of water. ($T$ = surface Tenson)
One has considered Surface Tenson along the line AB, which is equal to
$F_{ab} = 2RT$
I think there should be another surface t... |
Why does the equation of a wave contain the term $\omega t$ instead of $vt$ in the wave equation
$$y=A\sin (kx-\omega t).$$
I think of the constant $k$ which for higher values increases the frequency $f$ of the wave (decreases the wavelength $\lambda$ of the wave) or vice versa when $k$ decreases.
And the graph shifts ... |
Peskin and Schröeder make the following statement
$$\int_0^1dxdydz\ \delta(x+y+z-1)\frac{1-4z+z^2}{\Delta(q^2=0)}=\int_0^1dz\int_0^{1-z}dy\frac{-2+(1-z)(3-z)}{m^2(1-z)^2},\tag{p.195}$$
where $$\Delta = - xyq^2+(1-z)^2m^2.\tag{p.192}$$
Why does the integral of $dy$ go from $0$ to $1-z$ and not from $0$ to $1$? Also the ... |
I am looking for a vector potential
$$\mathbf{A}=(A_x,A_y,A_z)$$
giving a monopole magnetic field
$$\mathbf{B}=\mathbf{\nabla}\times \mathbf{A}= g\frac{\mathbf{r}}{r^3} = g \left( \frac{x}{r^3}, \frac{y}{r^3}, \frac{z}{r^3} \right)$$
for which there exist functions $f_x(r)$, $f_y(r)$, and $f_z(r)$ of $r$ satisfying the... |
I work in machine vision and in the last few years cheap collimated backlights have become widely available. Before, you had to buy huge telecentric illuminators to get that effect, but these days a not-as-great-but-still-very-good solution is available in the form of a standard backlight (a bunch of flatly arranged LE... |
Total energy for MnO magnetic solid by considering a spin configuration in which all Mn Spins are ferromagnetically aligned can be written as:
by mapping the energy on following the Heisenberg model
where the second term accounts for the NN pairs and the third term accounts for NNN pair. Here S is the Spin Magnitude... |
In the case of non-stationary spacetimes finding the event horizon is no easy task.
The stationary case should somehow be less involved or so it is in some well known cases, such as the Kerr spacetime.
I find (apparently) conflicting information about the way one finds the event horizon in such cases and I want to unde... |
So we assume that the electric potential of a point charge has the following form:
$$
V(r) = \frac{1}{4 \pi \varepsilon_0} \frac{q}{r^{1+\epsilon}}
$$
rather than the usual Coulomb potential.
Now we have a spherical shell made up of these point charges, and the shell has uniform surface charge density $\sigma$.
How do... |
Given a quantum state $\rho$ in a Hilbert space $\mathcal H_S$, we can always write it in terms of the displacement operator $D_\alpha$ using the characteristic function $\chi_\rho(\alpha)=\text{Tr}[\rho D_\alpha]$. If we have a composite state $\rho\otimes \tau$ in an enlarged space $\mathcal H_S\otimes \mathcal H_A$,... |
I was studying the mathematical description of gauge theories (in terms of bundle, connection, curvature,...) and something bothers me in the terminology when I compare it with general relativity.
In gauge theory, take a vector bundle $E \rightarrow M$ over a Riemannian Manifold $(M,g)$ and suppose you have a connectio... |
Liquid is streaming steadily and irrotationally in 2D in the region bounded by one branch of of a hyperbola and its minor axis. Find streamlines.
I am unable to proceed in such a question of flow bounded in a region.
What should be the approach? Should we try to find complex potential and then the streamlines?
|
When applying molecular dynamics, it is generally assumed that the equilibrium positions of the atoms are fixed, in which case the calculated displacements of the atoms are the displacements with respect to their equilibrium positions. If one wants to study the macroscopic rotation (i.e., all atoms rotating at the same... |
We have the average, root mean square, and most probable velocities of a gas as
$v_{av}=\sqrt\frac{8KT}{\pi m}$ ; $v_{rms}=\sqrt\frac{3KT}{m}$ ; $v_{mp}=\sqrt\frac{2KT}{m}$
For a mixture of two gases, I have derived the following :
$v_{av_{mixture}}=\frac{N_1v_{av_1}+N_2v_{av_2}}{N_1+N_2}$ , and $v_{rms}=\sqrt{\frac{... |
I'm watching these lectures in Condensed Matter Physics. At Lec. 13, the lecturer introduces the transverse field Ising model with the Hamiltonian
$$H = - J \sum_i \sigma_i^x \sigma_{i+1}^x - h \sum_i \sigma_i^z.$$
After looking at it for a while, it seems to me this is not a Hermitian Hamiltonian, because
$$(\sigma_i^... |
I am reading a paper that derives the form of the Bloch Hamiltonian using the symmetry arguments. Let $D(k)$ be the Bloch Hamiltonian, where $k$ is the wavenumber. The part that I am trying to understand is
What I understand is that the authors are describing the Bloch Hamiltonian in terms of the eigenmodes of a unit ... |
Tidal forces are encoded in the Weyl-tensor $C^\mu_{\nu\lambda\sigma}$. It is well-known that the Weyl-tensor is invariant under conformal transformations: $g'_{\mu\nu}(x) = \Omega(x)g_{\mu\nu}(x)$.
In other words tidal forces are conformally invariant. Can this be understood intuitively ?
|
Starting from the Kähler potential
$$\mathcal{L}=\frac{1}{4\pi} Im(\int d^{4}\theta tr(\Phi^{\dagger}e^{2V}\Phi),$$
How do we integrate out to get the following Lagrangian:
$$\mathcal{L}=\frac{1}{4\pi} Im(\int d^{4}\theta F'(A)\bar{A}+\int d^{2}\theta \frac{1}{2}F''(A)W^{\alpha}W_{\alpha})~?$$
Which we see in Seiberg-W... |
I am computing the commutator of the Lorentz generators, from the Eqn (3.16) to Eqn (3.17) in Peskin & Schroeder.
$$
\begin{aligned}
J^{\mu\nu} &= i(x^\mu \partial^\nu - x^\nu \partial^\mu ) &(3.16)\\
[J^{\mu\nu}, J^{\rho\sigma}] &= i (g^{\nu\rho}J^{\mu\sigma} - g^{\mu\rho}J^{\nu\sigma} - g^{\nu\sigma}J^{\mu\rho} + g^{... |
Why is the speed of light 300 000 km/s? The speed of light is slower in glass, water and diamond. Is the speed of light in water, glass and diamond also absolute? Can we calculate the material such as glass by calculating the speed of light in objects? From these questions, I finally want to answer this question, is it... |
I've been trying to solve this but I'm stuck. I thought the formula for Coulomb's law was $$F = (k* q1*q1)/r^2.$$
In the solution, first the charge is divided by the distance and then the whole thing is squared.
Is coulomb's law different for equal charges or is the solution wrong?
|
I'm looking for books on a complete analysis of co-planar capacitors and their electric fields at DC, such as between narrow and wide traces on a PCB. Any suggestions?
I think there's a some research literature that might help, but its an expensive gamble to access.
|
Maldacena and Susskind have "formulated" the now famous ER = EPR conjecture in their paper Cool horizons for entangled black holes, but as of today, I have not find a quantum theorist who can precisely describe what Maldacena and Susskind actually mean (including Maldacena and Susskind).
Quoting Peter Woit:
My problem... |
More specific, short form of my question:
POVMs assign expectation values of positive operators (summing to identity) to probabilities of events, but not a particular measurement scheme, leading to no well-defined notion of canonical post-measurement state. Projective measurement assigns expectation values of particula... |
Attempting to model the diffraction for a black-body source, I have stumbled upon a bit of a conundrum with the mathematics. I am not asking WHY the light is diffracted, but instead looking for a detailed analysis of the diffraction itself.
Modelling the diffraction for an image is also well understood in the theory of... |
In fluid dynamics, why does the density of air decrease more above Mach 0.3, and not as much below Mach 0.3? From what I've heard, it isn't a linear relationship but why is that? Asked differently, what makes it a non linear relationship? I welcome a non-mathematical explanation, instead more of explaining what happens... |
I noticed that when bending a large plate it makes a howling sound. However, having made a number of experiments I found that if we bend the plate from the initial position, we will not hear the sound. But if we first bend it a little and turn it sharply to the other side, we will hear this howling sound. With the help... |
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