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I have been trying to study Quantum Field Theory and have come across Green's Functions for the first time. While referring to Tom Lancaster's book Quantum Field Theory for the Gifted Amateur, the author states in Eqn 16.13 that $$\phi(x,t_x)=\int dy\ G^{+}(x,t_x,y,t_y)\phi(y,t_y)\tag{16.13},$$ where $G^+$ is the time-... |
As everyone knows, an object with color appears that way because it reflects its specific color(s). Textbooks tell us other colors are absorbed. Now, here's the question: what happens to the absorbed light?
For example, a red rose absorbs all colors except red, which is why it appears red to us (according to the widely... |
SO basically , I know that a battery creates potential difference or V in a circuit to flow, by doing work on the charge(electrons) . The motion of the charge(electrons) is from the -ve or negative end to the +ve or positive end(i.e- the positive terminal of the battery). SO what happens to that charge(electron) when i... |
I have a homework problem that seems wrong. Previous to the problem we showed that the inner product of a vector space $V$ on the field $\mathbb{C}$ defined as
$$ \langle v,w \rangle = a^i(b^j)^*\delta_{ij} $$
where $a^i, b^j$ are the components of the vectors $v = a^i e_{i}$, $w = b^i e_{i}$ satisfy the inner product ... |
It is possible for a larger (wider, but less massive) star to mutually orbit a heavy dwarf companion star in a binary system. If the dwarf star gets close enough it can attract the corona of the larger star, removing it.
How close do their orbits have to be for this?
I could calculate the distance at which a test parti... |
So in SHM, $v = r\omega\cos\omega t$. But we also know that $v = r\omega$ from circular motion. Then, we can write
$$r\omega = r\omega\cos \omega t$$
$$1 = \cos\omega t \tag{1} \label{1}$$
$$0 = \omega t \tag{2} \label{2}$$
Equation $\ref{2}$ comes from equation $\ref{1}$. Then from $\ref{2}$, $\omega$ should always be... |
Suppose we have a system with Two point masses of mass $M$ and mass $m$. And we want to derive Work done. Lets say M is fixed or $M>>m$. Initially assume mass m is at rest at a distance of $a$ from $M$ and after some time it reaches $b$. And we want to calculate work done. Since magnitude of Gravitational Force is $\fr... |
In physics problems, I struggle to incorporate the ideas of angular conservation and torque. For example, how do I know when torque is zero in a problem like this:
can I even apply angular momentum in this problem?
I understand that for the most part the angular momentum is conserved and constant when torque is zero... |
Several sources claim that Self-Phase Modulation (SPM) can prevent mode locking (ML) in fiber lasers (e.g. rp-photonics). I have experience of a silica fiber laser based on active ML where steady state is achieved until the optical pump rate reaches a certain threshold. Below this threshold the laser output pulses are ... |
Physically, the electric field is defined as:
the force per unit charge that would be exerted on a test charge.
What is confusing me here is what exactly is meant by
per unit charge
If the definition of electric field was defined as
The force that a test charge (of any magnitude) would experience when placed at a ... |
so i'm a 7th grader trying to create something using a high bypass turbofan engine but I need to learn how to calculate the thrust for it and i'm unsure on how I am meant to do that. If anyone has any answers for me it would me much appreciated.
|
Context : an exercise gives the temperature, mass, distance and apparent magnitude of Sirius B and asks to calculate its density.
One key step of the calculation is to get the luminosity from the absolute magnitude (with the intent of then using Stefan-Boltzmann law to get the area).
I get this step wrong. With an abso... |
Let's say I have a system with two species of fermions, $f$ and $c$, where $f$'s are neutral but $c$'s are charged. Each of these has its own $U(1)$ related to particle-number conservation.
Now, if I consider an object $\phi = c^\dagger f$, I expect that this is bosonic because it is the product of fermion operators.
I... |
Consider the 2 point function in $\phi^4$ theory which is given as something proportional to
$$\int D(x-z) D(y-z) D(z-z) d^4 z,$$
where $D$ is the propagator. The corresponding Feynman diagram looks like this:
I understand where this comes from, but one thing I cannot figure out is why the vertex at $z$ is not connect... |
Does anyone know a theoretical study or an experimental study of the electromagnetic ambient power density at different wavelengths? To ask simply, how much electromagnetism are human usually exposed to?
Indoors, I am thinking lighting, appliances, thermal, solar, wireless communications, wired devices, building materi... |
I came across this uncertainty relation for Density of states $N$ and phase $\theta$ in "Introduction to Many-Body Physics" by P Coleman on Page 15, equation (2.20).
$$\Delta N\Delta\theta >\approx 1\tag{2.20}$$
I am unable to understand this relation between $N$ and $\theta$ algebraically especially in how these two d... |
According to special relativity the information can transmit only at the speed of light. However,the electric field at a point due to a charge moving at constant velocity changes its direction the moment charge moves and is always radial from the instantaneous position of charge.How?
|
I'm currently studying spin geometry through Hamilton's book Mathematical Gauge Theory. At a given point, Hamilton considers a pseudo-Riemannian manifold, which I'll take to be Lorentzian in $d=3+1$ spacetime dimensions for concreteness and simplicity. Hamilton states that the bundle of frames can be seen as a principa... |
Using the Schwarzschild metric and the mostly minus signature, how can I calculate the $9.81$ m$/$s$^2$ of acceleration on Earth using general relativity and the geodesic equation?
|
I could really use your help in understanding how a Faraday cage and Maxwell's Equations come together.
From my understanding:
For the electrostatic case, the Faraday cage cancels out an incoming Electric Field by rearrangement of the charges relating this case to Guass' Law.
For magnetostatics case, the static magneti... |
I'm looking at solutions to the massless Dirac equation in an accelerating frame of reference in $(1+1)$-dimensions but the wave functions I get appear to violate probability conservation.
My accelerating (Rindler) coordinates are defined through
$$
t= X \sinh(\alpha T), \quad x = X \cosh(\alpha T),
$$
$$
T= \frac{1}{\... |
I am working through Griffiths Electrodynamics and am having trouble reasoning through a step in example 4.8. More specifically, I do not understand whether to use the electric field outside or inside the dielectric when calculating the polarization vector.
In this example the entire region below z = 0 is filled with a... |
In Electricity and Magnetism by Bleaney & Bleaney (3rd Ed.) pg 18 they state:
In a dielectric where $ \chi_e $ (the susceptibility) is uniform, isotropic and independent of field strength there is no volume distribution of charge... This follows from the fact that $ \nabla \cdot \vec{E} =0$...
I have assumed that vol... |
We've learned in lecture about electric dipole transitions for hydrogenic atoms, and our professor claimed that $\langle\vec{d}\rangle=0$ for stationary states, but not for superpositions of states. This makes entire sense for stationary states:
For a stationary state, $\langle\vec{r_e}\rangle=0$ because the electron i... |
My question is very simple: let a plane monochromatic electromagnetic wave's electric field be:
$$\vec{E}=\begin{pmatrix}0\\1\\-i\end{pmatrix}e^{i(kx-\omega t)}$$
as you can see, the electric field is completely polarized (circular polarization) and I want to obtain its corresponding magnetic field. Therefore, I simply... |
Considering the infinitesimal form of the Lorentz transformation $x^a \rightarrow x^{\prime a}=\Lambda_b^a x^b = x^a+\omega^a_b x^b$ (which preserves the Minkowski metric, such that $g_{a b} x^a x^b=g_{a b} x'^a x'^b$ or $g_{\mu \nu}=g_{a b} \Lambda^a_\mu \Lambda^b_\nu$ for all$x$, and where $\Lambda^a_b=\delta^a_b+\om... |
In optical media, the real part of the electric susceptibility, Re{$\chi$}, can, in general, become negative for certain frequency ranges (near the absorption resonance). This leads to the refractive index, $n$, being less than one ($n \approx 1 + \frac{Re\{\chi\}}{2}<1$). It's noteworthy that when $n<1$, the phase spe... |
Today in class we were reviewing free body diagrams and we encountered a problem where an individual placed a block on their hand with their palm facing the ceiling. This is just a simple free body diagram where there is simply a normal force upwards and gravity pulling your hand down. However, I then wondered what for... |
I'm currently designing a closed tea strainer / egg made of stainless steel and testing a prototype made of polycarbonate plastic. The problem I'm facing likely has to do with the capillary effect - when I submerge my prototype repeatedly, the water seals the holes and causes it to float. The strainer itself isn't too ... |
Say I have a circuit where the wire has a shape defined by some closed
Parametric defined as $(X(t), Y(t), Z(t))$ (it is a loop), how do I calculate the entire magnetic field around the circuit?
|
Image from Sakurai, Modern quantum mechanics.
Question: Why $\partial_z(\mu\cdot B)\simeq\mu_z \partial_z B_z$? it's because $\mu_z$ is constant with respect to the $z$-axis? thanks.
|
In terms of vectors:
$$
L = r \times p
$$
and torque:
$$
T = r \times F
$$
In both these cases what exactly does the $r$ vector represent? Is it vector from origin of axis or center of mass? How would $r$ look like in an example of a spinning disc? Any other good examples to improve intuition?
|
A basketball coach showed me that when you bounce a basketball back from the ground, it is much easier to kick it far away (actually it shoots out like a rocket), but when you want to kick it like a soccerball (dropping it on your feet from your hands), it is very hard to kick it far (actually it feels like a heavy roc... |
Background
The standard model of particle physics is entirely determined by writing down its Lagrangian or, equivalently, writing down the corresponding system of PDEs.
Every set of PDEs has a corresponding set of "continuous symmetries" (essentially continuous changes of variables). The well-known (non-discrete) symm... |
I'm currently conducting a physics project for school and I am really stuck on uncertainties. I am trying to calculate the overall uncertainty in Young's Modulus, with the Bending Beam experiment using the equation $$E=(mgl^3)/(4bd^3s).$$ In this equation, $E$ represents Young’s Modulus, $m$ represents the mass of the ... |
I was reading through David Tong's Lectures Notes on Quantum Field Theory and I was wondering how, on page 22, he derives that the Fourier transform of $\phi(\vec{x}, t), \tilde{\phi}(\vec{p}, t)$, satisfies
$$
\left(\frac{\partial^2}{\partial t^2}+\omega_{\vec{p}}^2\right) \tilde{\phi}(\vec{p}, t)=0,\tag{2.6}
$$
where... |
There is a total solar eclipse happening in North America in early April. People will be travelling long distances to see it, and towns near where I live are warning residents to buy gasoline in advance so they won't need to go out on the day (due to crowds) and warning visitors that parking and restaurants may all be ... |
well i was confused about something when we are comparing Schrodinger equation by classical mechanics, we can see it contains the total energy (or the Hamiltonian) equals the kinetic energy plus the potential energy $E = \frac{p^2}{2 m} + V$ , now comparing to classical mechanics we can see this relation equals the me... |
Should there be a decomposition of the vector components to consider the component perpendicular to the wall and then perform a vector addition?
In other words I don't understand why the total force is calculated as just a sum of the magnitudes of the force:
$$ F_{total}=mv_1^2/l +mv_2^2/l +mv_3^2/l ...????$$
where $ l... |
In Newton's second law F = ma, the mass is the object the force is being acted upon. But in a gravitational system, does that mean the mass of the object you are concerned with? For instance, if you are trying to figure out the acceleration of the Earth, do you only input the mass of the Earth into the equation?
|
What if the object is completely red, then when I heat this object would it emit a blackbody spectrum except for the red color?
|
Say you have a plate facing the airflow right over a wing. Not attached, but just right over it. If flow separation and drag on the rear side of the plate (rear meaning the trailing edge of a wing) wasn’t a thing, would there be any drag at all?
Basically does any drag come from the high pressure in front of the plate?... |
I am curious about how different rotations on the Bloch sphere are done in practice. For example, assuming we start in the lower energy state of the $z$-axis (call it $|0\rangle$), a resonant rotation on the Bloch sphere by around the $x$-axis will take you to $\frac{|0\rangle-i|1\rangle}{\sqrt{2}}$ (where $|0\rangle$ ... |
In the He-Ne laser, if the collisions between the He and Ne atoms are inelastic, where does the lost energy go?
Does it go into heating the cavity?
|
My textbook:
The second bit confuses me. I asked a question on this site yesterday (Moment of Inertia tensor confusion) which involved the moment of inertia tensor and the term $$r_{i}r_{j}$$
The responses said that this results in a scalar because the $i$ and $j$ are indexing a vector which is a scalar. This makes se... |
is there a way to find the approximate force exerted on a iron cylinder of dimensions (height 1cm, radius 0.5 cm) when it is placed in a magnetic field (Generated by a solenoid). I am trying to make a rail gun kinda thing to pull a 30N weighted object vertically up.
|
Let's consider a block on a frictionless table. The block is connected to a fixed support on the table via a massless spring. Suppose the block is pulled aside by a distance x and then released. The potential energy of the "block+spring" system at the instant of release is taken to be 1/2 kx2 (provided potential energy... |
We have all learned about the Higgs mechanism in the standard QFT course. Given a complex scalar $\phi^4$ theory with global $U(1)$ symmetry, when $U(1)$ is spontaneously broken, the phase fluctuation is the associated gapless Goldstone mode. However, if $U(1)$ is gauged, the would-be Goldstone boson is "eaten" by th... |
In the Faddeev-Popov procedure of path integral of
$$
Z[J] = \int [DA] e^{iS(A,J)},
\quad S(A,J)= \int d^4x [-\frac{1}{4}F^{a\mu\nu}F_{a\mu\nu} + J^{a\mu}A_{a\mu} ]
$$
we have used that $S(A,J)$ is gauge invariant:
$$
S(A,J) = S(A^U, J), \quad A^U_\mu(x) = U(x) A_\mu(x) U^\dagger (x) + \frac{i}{g} U(x) \partial_\mu U^... |
I try to read a paper on general relativity and perturbation theory:
https://arxiv.org/abs/2109.01398 page16
My question is about equation (3.16) in section (3.2):
$$
\delta \phi = -\sqrt{\frac{2}{\epsilon}} \left( \Phi+ \frac{\Phi’}{H} \right)
$$
Where $\delta \phi$ is the first-order perturbation of a scalar field, ... |
In the weak field limit of general relativity (with matter described by a perfect fluid consisting only of dust), we have the following correspondences:
$00$-component of the Einstein field equations (EFEs) $\leftrightarrow$ Poisson's equation $\nabla^2\phi = 4\pi G \rho$;
spatial components of the geodesic equation $... |
I'm currently delving into the fascinating topic of electrostatics, specifically the distribution of potential in configurations involving conducting plates and charged wires. My focus is on a setup consisting of two infinite conducting plates, one aligned along the x-axis and the other positioned at $y=a$, with an inf... |
I have been studying the oscillations of a ball attached to a string which is released from some initial angle $\theta$. The number of complete oscillations over a certain time interval $\Delta t$ is plotted on the $y$-axis of the below plot and I plot
$\frac{l}{(\Delta t)^2 g},$
on the $x$-axis, where $l$ is the leng... |
$\newcommand{\ket}[1]{| #1 \rangle}$
The general spin formulation is the same as the cinetic momentum :
\begin{equation}
[S_{x},S_{y}]=i\hbar S_{z},\quad [S_{y},S_{z}]=i\hbar S_{x},\quad
[S_{z}, S_{x}]=i\hbar S_{y}
\end{equation}
with other spin operators :
\begin{equation}
S^{2} = S_{x}^{2}+S_{y}^{2}+ S_{z}^{2}\quad,\... |
I've been trying to self-learn how to do basic QFT calculations and I'm a little bit confused as to what's considered "an interaction". If I want to model an electron releasing a photon I can use a bunch of feynman diagrams, some of which will have off-shell particles in them, but in all those diagrams the outgoing pho... |
I'm using Kohn-Sham DFT as a part of my research. The material is metallic crystal. In the following, you can assume that $\rho$ refers to the density matrix and $H$ refers to a hamiltonian matrix that have been expressed in an atomic orbital basis. I want to calculate the forces on the atoms. My Ph.D. supervisor has s... |
Since angular acceleration is absolute on entire body (correct me if i am wrong), can we choose an arbitrary axis to calculate the torque and then calculate the angular acceleration? (Regardless of how the calculations be difficult.) If it is possible, what will be the meaning of the calculations and torque values, s... |
Imagine, 3 completely equal tornadoes with similar spin are compressing together by huge outer force in one axis and we can control the amount of outer force, what will happen as we gradually increase that force? How these tornadoes change their shapes, spins,relations for adaptation ?
|
We observationally determine whether a quantity can be a vector or not. For example, we chose force and momentum to be vectors to due to the fact that inertia depends on direction.
Then it seems like angle $\theta$ (in radians) should be scalar but we chose theta to be a vector perpendicular to the plane, just so that ... |
It is known that quantum channels, being CPTP maps, map density operators to density operators. And thus, they can be seen as superoperators. Similar to operators, where eigenstates and eigenvalues can be derived, one can also define the eigen-operators (typically, being a mixed state) and eigenvalues of quantum channe... |
I have a small window through which I can view the moon only at some times for few minutes,I am keen to understand and study moon positioning to predict when shall be the next day I shall view moon through my window ,I tried studying moon position, azimuth,moon rise and moon set and the cycle of moon which is 29.5 days... |
Question:
I have a conceptual question regarding $4$-dimensional compactifications in string theory. For example, if we consider flat $10$-dimensional space with D$6$-branes, we obtain $7$-dimensional gauge fields from strings attached to such a brane living in the $6+1$-dimensional world volume of the D-brane.
Now, if... |
I'm getting started with electronics and couldn't help but wonder about this. When the PN junction diode is reverse biased, P connected to the negative terminal and N connected to the positive terminal, shouldn't there be a large reverse current as the electrons (which are essentially the equivalent of minority charge ... |
I'm dealing with the Pusey-Barrett-Rudolph (PBR) theorem proof, in which we are using a basis built of linear combinations with tensor products.
I'm trying to figure out whether measuring those linear combinations is still in terms of spin unit? Because our states kets with zeros and ones represent spins, but I'm not s... |
With reference to central force, we see that K.E has 2 terms in 2D cartesian cordinate but just 1 term in polar coordinates and potential energy has 1 term in cartesian but 2 terms in polar.
Basically magnitude of K.E and P.E can change with choice of coordinates? Doesn't it sound strange? Though i understand total ene... |
Say my fluorophore's resonance wavelength is 500nm. I excite the fluorophore with equal energies of 500nm and 550nm. The 550nm light excites the fluorophore, but is inherently weaker than 500nm excitation as the resonant wavelength is 500nm for this material. Say the emission intensity of 550nm is a value of x. If we e... |
I'm reading Einstein's special relativity paper and couldn't understand the condition for synchronizing given in the following paragraph taken from the paper -
If at the point A of space there is a clock, an observer at A can determine the time values of events in the immediate proximity of A by finding the positions ... |
Suppose there is a cylindrical (pellet) sample in the oxygen atmosphere as shown on the photo attached. Oxygen diffuses from the outside to the sample interior everywhere on the outer surface of the sample. From the photo, it can be seen that diffusion profile of oxygen is measured in the axial direction of the cylinde... |
I have taken a lab course this semester and one of the experiments is the Lee's disc method to determine the conductivity of a poor conductor. For anyone unfamiliar with the experiment, this is the experiment. In the second part of the experiment, where the lower disc is directly heated and then, after heating is coole... |
I'm studying about electricity and i'm quite lost.
Given the circuit in the picture, I just want to know how the current flows through the points A, B, C, D.
The condition to have current between 2 points is to have potential difference between them.
From what I understand, between A and D, there is a potential differe... |
In the long range, a magnet can be approximated by a dipole. It produces a magnetic field $\vec B$:
$$\vec B = \frac{\mu}{4\pi}\left[\frac{3\vec r (\vec m · \vec r)}{r^5}-\frac{\vec m}{r^3}\right]$$
What is the typical value of a fridge magnet? Or some object that we can find at home.
|
I've studied that if a mass is ejected from the surface of the Earth at 11.2 km/s (or at any point above the surface at a lower Ve), it 'escapes' to infinity.
Does that not imply a violation in the law of conservation of energy? In such a case I'm giving an object only definite energy to move it out of the earth's Grav... |
If a photoelectron was liberated from the material it was in, and all of the energy transferred to the electron from the photon was used to overcome the bonds in the material (where hf = work function) then the electron will have 0 kinetic energy. In this case, will the electron just be attracted to the positively char... |
The argument for Bremermann's limit, as I understand it, goes something like this:
Begin with the time-energy uncertainty principle, as
$\Delta E \Delta t \ge h$ (Other papers use other factors of $h$/$\hbar$, but Bremermann (1962) uses $h$, so let's stick with that.)
Substitute $\Delta E \le mc^2$ to get: $mc^2 \Delta... |
In standard quantum mechanics, the atomic orbitals are represented by the following wave functions (where $u = 2 \mathrm{Z} r / n a$):
$$\tag{1}
\psi_{n l m}(r, \theta, \varphi) = \phi_{n l}(r) \, Y_{l m}(\theta, \varphi) = N_{n l} \, u^l \, e^{- \frac{1}{2} \, u} \, L_{n - l - 1}^{2 l + 1}(u) \, Y_{l m}(\theta, \varph... |
For example, I came across this statement:
"It is a fact that the components of force are derivatives of potential energy, but it is not a definition."
What does this statement mean?
I know that we can't always find a function $V(x)$ in which:
$$F_i(\{x\})=-\frac{\partial V(\{x\})}{\partial x_i}$$
Does the statement ... |
I recently asked this question about variational principles and how it all works. The essential answer I got was to go read a book on the calculus of variations, which I did, and this helped me make sense of what was going on. I have one lingering question.
For finite volume $\mathcal{R}^3$ and $V=\mathcal{R}^3\otimes[... |
I'm currently exploring several concepts related to universality classes, phase transitions, and critical phenomena. My questions revolve around the comprehensiveness of universality classes, the classification of systems with multiple transition points, and the identification of new universality classes based on criti... |
I've been delving a bit beyond just using what's typically given as the "electric field" and "magnetic field" in various problems, and finding out about the various more fundamental quantities and how they relate to one another; but as I've been reading that relationships between the magnetic quantities on the one hand... |
The spin angular momentum magnitude squared operator:
$$S^2=S_x^2+S_y^2+S_z^2=\frac{3\hbar^2}{4}
\begin{pmatrix}1&0\\0&1\end{pmatrix}$$
Obviously $S^2$ commutes with everything, so why do QM books
point out that it commutes with $S_x$, $S_y$, and $S_z$?
Since any vector is an eigenvector of $S^2$, it seems like a trivi... |
When our entire section of the universe was in a single hot dark dense state, right before our big bang, what was the escape velocity?
|
There is a bridge supported at both ends. The reaction forces at the ends are currently the same. A vehicle comes on to the bridge and stops at 50 m from one of the ends. What are the reaction forces from the two supports? Bridge is 5000 kg, vehicle is 1000 kg and the bridge's full length is 200 m.
I know the answers... |
if people in semi-light-speed ships age slower, does the world appeared to those people also 'age slower'? Because it is the external world which is moving at semi-light-speed to the people in the space ship. But the external world should appear to 'age faster' since when the people on the space ship return to earth, t... |
In coherent population trapping, if we denote the ground states in a $\Lambda$-like system as $|0\rangle$ and $|1 \rangle$ and the excited state $|2 \rangle$, there is a linear combination $|d \rangle = \sin\theta |1 \rangle + \cos\theta|0 \rangle$ for some $\theta$ which usually depends on the laser intensity, which ... |
Consider the following example:
A mass ($m_1$) is stacked on top of another mass ($m_2$) resting on a frictionless table in a vacuum. There is a nonzero coefficient of static friction ($\mu_s$) between the masses. What is the maximum force $F$ that can be applied to the top mass such that no slipping occurs?
Clearly, ... |
I know that the Meissner Effect is fundamentally quantum, but can a similar logic to the one used for normal conductors be applied to superconductors? I am referring to the idea that in normal conductors, charges move so smoothly such that when there is an external electric field, all the negative charges get pulled to... |
Hoping to resolve a simple confusion I have about supersymmetric gauge theory, one which I ran into while trying to understand the ${\cal N}=1$ superfield formulation of ${\cal N}=4$ supersymmetric yang mills.
In various sources
(e.g. this review: https://arxiv.org/abs/hep-th/9908171 see eq'n 2.9, or Erdmenger's book G... |
It is often said that a Bose-Einstein condensate of cold atoms is a gas. But because of Andrews' discovery of the critical temperature, we know that a gas and a liquid is not fundamentally different. So, why is it called a gas but not a liquid?
|
Say I consider an amperian loop surrounding the sphere, wouldn't the net current through it be zero as the current entering the loop due to one half of the sphere and the current exiting in the opposite direction are equal in magnitude? However this contradicts the fact that magnetic field outside such a system is not ... |
I am talking about the way we generally explain the occurence of bright and dark fringes during diffraction. When we want to show a dark fringe we consider a pair of secondary light sources who have a path difference of λ/2.
Like If the slit width is "a", we see that dark fringe is obtained where asinθ=λ. Suppose we as... |
In weinberg's gravitation and cosmology in page 77 appears this
I can't see why the equation and the symmetry of Christoffel symbols and equation 3.3.5 makes that equation 3.3.10 appears
I ask my teacher for a similar proof with euler-lagrange equations, but he insist that Is only with the identity 3.3.5 AND playing ... |
What happens to the poisson bracket structure of Hamiltonian phase space if We have some constraints in $p$ and $q$. What physical aspects this structure represents?
|
How can one analyze the phonon dispersion of 2D materials like graphene to discern specific curves corresponding to particular phonon modes, such as acoustic or optical, as well as longitudinal and transverse modes?
|
I'm reading a paper on cosmological perturbations.(https://arxiv.org/pdf/0809.4944.pdf) When FRW metric is perturbed to 2nd order, we have (see Eqs.(2.15) in that paper)
$$
g_{00}=-a^2(1+2\phi_1+\phi_2)\\
g_{0i}=a^2\left(B_{1i}+\frac12B_{2i}\right)\\
g_{ij}=a^2[\delta_{ij}+2C_{1ij}+C_{2ij}]
$$
while $g^{00},g^{0i}$ and... |
can someone please explain to me why potential gradient at the planets surface is not greater in magnitude than the potential gradient at surface of moon B even though planet has a much greater field strength?
I understand that the graph is the resultant G.P and so the gradient is the resultant field strength of both ... |
In the Derivations sections of the First chapter of Goldstein's Classical Mechanics, we find the following question:
Suppose a system of two particles is known to obey the equations of motion, Eqs. (1.22) and (1.26). From the equations of the motion of the individual particles show that the internal forces between p... |
I read somewhere the following statement: In a partial differential equation (PDE) in order to get the property of time reversibility in your solutions, you need to set the initial condition $u'=0$ (time derivative equal to zero).
Specifically, they were talking about sine-Gordon equation. In order to numerically solve... |
When I conducted the experiment of finding out the Planck’s constant using a photoelectric cell, I tried to verify that the intensity of light doesn’t affect the stopping potential. Doing this I encountered some problems:
Stopping potential for a fixed wavelength (say 540nm) was changing with changing the intensity of... |
I read paper on open quantum system, that talk about non-Markovian process and memory effects.
they described the system as a generic decoherence model of two qubits interacting with correlated multimode fields.
when they described the interaction and the evolution in time, they say that the unitary U work like this:
$... |
I am reading the Polymer Scattering wikipedia page (https://en.wikipedia.org/wiki/Polymer_scattering). I don't understand how using an isotropic assumption they have gone from the first equation to the last equation. I thought it might be a taylor series followed by some approximation but I have not been able to work i... |
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