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No one has observed before a "free" quark, i.e. a quark in an unbound state. According to one paper, I read that $p\bar{p}$ collision produce unbound $t\bar{t}$ pair which quickly decay into other particles. But some people argue that the produced $t\bar{t}$ pairs decay so quickly that they had no time to bind! And I a... |
Question: Why are the electric and magnetic field components of guided EM waves independent of the direction of propagation?
Details: I'll go on to paraphrase Griffiths' section on guided waves here-
For a waveguide that is a perfect conductor, the boundary conditions at the inner wall are $E^{||}=0$ and $B^\perp=0$
Fo... |
Well, we know that it is impossible to say exactly when a radioactive atom will go on decay. It is a random process. My question is why then a collection of them decays in a predictable nature (exponential decay)? Does the randomness disappear when they get together? What is the cause of this drastic change of their be... |
There's very good table of different universality classes:
Ising model lies in the same universality class with $\phi^4$ theory.
Ising in $d≥4$ have critical exponents for free scalar field.
But I don't know field theories, which belong the percolation universality class. So I have few questions:
Which field theories... |
Can the topography of a terrain be measured by a gravimeter to give a clear image of the surface or sub-surface of a planet or does gravity scatter like light? In other words can the changes in gravity create a 3 dimensional picture of an object if close enough. The picture is speculation of how distance using gravimet... |
In this paper https://inspirehep.net/literature/152400, in eq.(3.4), it claims that
the MAC (most attractive channel) in $SU(4)$ gauge theory will attract
fermions in $[1]_4$
and
fermions in $[3]_4$
to form a bonus state: a Dirac fermion.
question 1 --- It looks that $[1]_4$ and $[3]_4$ both have fermionic statistics, ... |
I know there are particles with $1e$ charge like protons and electrons. Atomic nuclei can have charge of $Ze$ on basis of their proton number $Z$. Are there any particles out there with charge $2e$ or $3e$....etc?
|
I am thinking of the typical (sound, electromagnetic or whatever) signal which can be represented in time or frequency domain as a collection of infinite amplitudes for, respectively, each time-point or each frequency, so that one can say that this function (where the input is the time points or the frequencies, as the... |
We know that (see this wikipedia page) in the metric of Minkowski spacetime:
$$ds^2=(dt)^2-(dx)^2-(dy)^2-(dz)^2 \tag{1}$$
and we also know that in spherical coordinates this same metric becomes:
$$ds^2=(dt)^2-(dr)^2-r^2(d\theta)^2-r^2\sin^2{\theta}(d\phi)^2 \tag{2}$$
Let's prove this last statement:
We have that:
$$\be... |
I am studying how electric charge can be made to flow due to a change in the magnetic flux through a conductor, I understand if the magnetic flux changes there is an induced EMF in such a way to oppose the motion that caused it (Lenz's Law) however this confuses me as if this now induces a current then surely the force... |
I'm reading and trying to understand the paper by Diehl, S., Rico, E., Baranov, M. et al. "Topology by dissipation in atomic quantum wires". Nature Phys 7, 971–977 (2011). https://doi.org/10.1038/nphys2106, (also available at https://arxiv.org/abs/1105.5947)
I have faced some difficulties, though, mainly with notation.... |
You consider a shaft which can rotate freely (there will be of course a frame with ball bearing to hold the shaft firm and to allow it to rotate with low friction); fixed on this shaft there are two gears, one with radius $R$ and another with radius $2R$. Note that the two gears rotate together with the shaft since the... |
I had always been under the impression that animal exhalations were composed of air, carbon dioxide, and water vapor, meaning individual molecules of H2O in the form of a gas.
However, recently I read a paper which claimed that exhalations may contain hydrosols (aerosols of water) consisting of small spheres of water b... |
is deep inelastic scattering a process? and how is it (DIS) used to measure strong coupling constant?
the traditional method of measuring $α_S$ in deep inelastic scattering is from the strength of the structure function scaling violations predicted by the DGLAP equations.
how?
|
The Comet C/2020 F3 (also known as "NEOWISE") appears to move compared to stars in the background:
(Screenshots from Stellarium)
Those images are one hour apart as seen from Germany.
Is this parallax primarily caused by the motion of earth or by the comet's motion? We know that Earth is moving at around $30 \frac {km... |
We know examples of bosonization in 1+1 dimensional spacetimes, as well as some examples in 2+1 and 3+1 space-time dimensions are known in literature. Does this also work in quantum mechanical models in 0+1 dimension?
|
What is 'covariant variation'? As opposed to the usual variation with respect to a gauge parameter?
|
I'm sort of confused by this... let's just say the bulbs only emits green light, and we compare a 40 W and 100 W bulb (identical except one is brighter than the other), since the frequency of light emitted from both bulbs are the same, does it mean that there is more energy packed per photon in the light emitted from t... |
Consider a system with $N$ identical particles of mass $m$, whose coordinates and momenta are $(q_i,p_i)$, $i = 1,\ldots,N$, and with Hamiltonian
$$
H=\sum_{j=1}^N \frac{p_j^2}{2m} + \sum_{1\leq j < k \leq N} V(|\vec{q}_j-\vec{q}_k|)
$$
I have an issue with evaluation of the momentum equation $\dot{\vec{p}_i}$. If I wr... |
$$\begin{align}
\frac{\vec{d}}{t} &= \vec{v} & \frac{\text{vector}}{\text{scalar}} &= \text{vector} \\
\vec{d}\times \vec{d} &= \vec{A} & \text{vector}\times\text{vector} &= \text{vector} \\
\vec{d}\times \vec{d}\times \vec{d} &= V & \text{vector}\times\text{vector}\times\text{vector} &= \text{scalar} \\
\frac{\vec{F}}... |
Motion Creates Force ?:
When you move your hand (to push a box for example), it creates a force.
When electron moves through a wire it creates electrical force.
Or Force Creates Motion ?:
Gravity force caused an apple to fall.
We pushed a ball and it started to move, but friction force made it stop.
So which one is... |
Non-physicist asking.
Suppose two massive bodies approach each other at great speed. They pass non-destructively past each other and continue on, in their new directions.
Does the gravitational force between them constitute a wave (of very long wavelength). The magnitude increases as they approach; reaches a peak when ... |
The Wikipedia page on Georgi–Glashow model says
Fermions transforming as a 1 under SU(5) are now thought to be necessary because of the evidence for neutrino oscillations, unless a way is found to introduce a tiny Majorana coupling for the left-handed neutrinos.
This text tries to explain how the $$(1,2)_{-1/2}$$ of ... |
I understand that Fringe Fields exist on the edges of a parallel plate capacitor like so:
I was trying to figure out if a Cylindrical Capacitor would have fringe fields as well, and how they would look like (presuming it is a cylinder of a reasonable radius and finite length). In this image, I would think that that t... |
I'm working through Zwiebach's String theory book by myself and I'm having trouble starting problem 4.7. For those that do not have a copy, I'll paraphrase the question:
A string is stretched from $x=0$ to $x=a$ and has tension $T_0$, mass density $\mu(x)$. The string is fixed at its endpoints and vibrates in the $y$ d... |
Suppose we have a rigid body (or even a collection of point masses connected via rigid rods). Suppose this body is floating in space.
Suppose we apply a force on this body over a duration of time and in addition suppose as the body accelerates/changes position, the force stays the same with respect to the body.
How wou... |
Imagine a neutron star is being consumed by a black hole, so I think matter from the star is being stretched as it follows the curvature of the spacetime around the black hole. If that is the case what forces is stretching the degenerate matter?
|
When I fill the higher end of a hose till its overflowing. I can keep the lower end of the hose bout half a foot below it without water flowing out of it. The middle of the hose is all beneath the higher hose end. The crinks in the hose seem minor, especially since raising one end of the hose up and down shows changes ... |
Any answers are appreciated, thanks. :D
|
From what I've read, the green light found in the earth's auroras is the result of a reaction between oxygen and nitrogen (supposedly a new element was once proposed to explain it until the science was better understood). This happens, apparently, when electrons / and/or plasma are accelerated by the planet's magnetic ... |
One can define the Tachyon field in SFT via State-Operator correspondence by $\Phi(0)|0\rangle = c(0)e^{ikX(0)}|0\rangle = c_1|0;k\rangle$ with $|0;k\rangle = e^{ikX(0)}|0\rangle$. I'm trying to realize how to construct this field using another approach that makes clear the second quantized character.
To do this, anoth... |
My textbook says that the volume of liquids is assumed to be such under atmospheric pressure. What if the atmospheric pressure is reduced? Will the liquid stop exerting pressure according to Pascal's law? Will there be an intrinsic force that the liquid will exert?
|
Textbooks often mention that if we perturb a UV theory in the "direction" of a relevant operator, the fixed point theory one eventually ends up with, under RG flow, is/can be a CFT. Now, this answer gives an example of a CFT for which a Lagrangian description is not possible. On the other hand, when we do RG transforma... |
So I conducted a though experiment where I take a hollow spherical conductor and beef it up with a lot of electric charge. Here, I have ignored the ionization of air due to that huge amount of charge. Okay, coming to the point, is it possible that the hollow conductor, which is made of a certain metal and let's say if ... |
I'm self-studying Kibble & Berkshire Classical Mechanics, and I'm completely stuck on Problem 11 in Chapter 12 on Hamiltonian mechanics.
It asks about a particle of mass m and charge q moving (in the equatorial plane) in the field of a magnetic dipole of moment $\mu$ and described by a vector potential with the single ... |
A dog sleeping in a room and after some time it suddenly woke up and started running so its state of rest changed but no external force is applied on it.
Every one will answer this like **the leg of the dog applied force on earth and earth applied force against it **
But How did it's leg of the dog moved.
|
I'm having some problems understanding how if a moving object emits light, the speed of that light is still the constant, $c$, speed of light. According to Einstein's theory of relativity, light travels at the same speed for all inertial frames of reference. From what I understand if a driver driving a car at a constan... |
There are some universe models where $\Lambda < 0$. In this case, the energy density of the dark-energy becomes negative. At this point, does it make sense to talk about "negative dark energy density"? Or is it possible to think of this energy as curvature on space-time? Such that, $\Lambda < 0$ will imply a negative c... |
Consider the following problem.
Construct a pendulum with a mass $m$ at the end. However, we don't a rigid rod of length $\ell$, we instead use a spring of natural length $\ell$ and spring constant $k$. We lift the mass so that the spring is horizontal and at its natural length (i.e. $\theta = \pi/2$ in the picture). ... |
This question has been previously asked over here and the comment and answer there has already answered my original question (the one that I had in my mind), but the following question arises:
Why isn't it possible for the for a fluid to form the persistent structure$^{\dagger}$ above critical temperature?
I mean the... |
If I place a point charge $q$ inside a conductor, The electric field at any point inside it will be non zero ($Kq/x^{2}$). If we draw a Gaussian surface inside the conductor, the net enclosed charge will be $q$ that will provide an outgoing flux.
Then why do we say that the electric field inside a conductor is always 0... |
Suppose I have a square-shaped plate getting hit by a ball as shown in the picture below (notice how the force vector applied by the ball is not parallel to the $r$ vector). Let's set the origin to be in the point of the collision.
I know that the plate will now have both angular and linear speed so we can write the an... |
While there is a depletion of charge carriers close to the surface of most semiconductors, some semiconductors for example InAs, show a electron accumulation layer at their surface, where the charge neutrality level lies within the conduction band. Such electron accumulation layers induce the downward band bending at t... |
I have a doubt, I don't know how to understand generalized velocities, I have seen in the books that they are used like variables. But if they are the derivatives of generalized coordinates, why are they not functions?
I don't know if the generalized velocities are functions, parameters, variables or coordinate axes?
|
I have a puzzle about the optical conductivity. In Drude model, it is often said that the real part of tells us about the dissipation of energy in the system; the imaginary part of the conductivity tells us about the response of the system. for example in Tong's EM lecture or Tsymbal's lecture. On the other hand, the ... |
We can view the Leyden jar as a capacitor and a dielectric (glass). When the metal parts are charged thus is due to influence in the dielectric a counter electric field to be found.When we separate the metal parts the outer field disappears and to my understanding the glass should not be charged since we now have no ou... |
I think I'm fundamentally misunderstanding something.
Say I have a gauged Lagrangian for a complex scalar field $\phi$ with no SSB:
$$\begin{equation}
\mathcal{L} = (D_{\mu}\phi)(D^{\mu}\phi)^{\dagger} - m^2 \phi \phi^{\dagger} - \frac{1}{4} F_{\mu \nu} F^{\mu \nu}\tag{1}
\end{equation}$$
with $D_{\mu} = \partial_{\mu}... |
Suppose we have a point charge moving inside the halfspace $z>0$ with a given trajectory $r(t)$. Assume that $z>0$ halfspace is Vacuum and the $z<0$ halfspace is glass or some linear dielectric with electric constant $\epsilon_1$.
How can we describe the total electric and magnetic fields generated? If the charge is st... |
After reading this question on this site I learned that the direction of the magnetic field is given by $\boldsymbol{B}=\frac{1}{\omega}\boldsymbol{k}\times \boldsymbol{E}$
The left diagram below is a left-handed coordinate system, while the right diagram is a right-handed coordinate system:
The image above and the qu... |
I have a simple question, I probably misunderstood some minor thing, because this should be trivial.
My question is regarding the book Peskin & Schroeder 1995 Introduction to Quantum Field Theory, at page 59.
Question briefly
It seems to me, that there is a contradiction between (3.106) and (3.110). Let's say in coordi... |
I know that the complex conductivity ($\sigma = \sigma_1+i\sigma_2$) is related to the dielectric function ($\epsilon = \epsilon_1+i\epsilon_2$) by:
$$ \epsilon_1 = 1 - \frac{4\pi\sigma_2}{\omega} \\\epsilon_2 = \frac{4\pi\sigma_1}{\omega} $$
and I also know that, for semiconductors, the following relation exists:
$$\s... |
There is a ball and a beaker. The beaker is filled with a liquid which has higher density than that of the ball. By the help of some mechanical force the ball is inserted inside the liquid and is made to touch the bottom of the beaker. Then the mechanical force acting on the ball is removed. Since the density of liquid... |
I am reading the book "Gauge theory of elementary particle physics" by Cheng & Li chapter 16 and I am confused by some statements.
In Euclidean 4D spacetime we have a $SU(2)$ gauge teory
\begin{equation}
S_E=\int dx^4 tr(F_{\mu \nu}F_{\mu \nu}),~~~F_{\mu \nu}=\partial_{\mu}A_{\nu}-\partial_{\nu}A_{\mu}+[A_{\mu},A_{\nu}... |
I came across a video on youtube in which Alexander Unzicker argues that in order to have a scientific revolution, one of the constants of nature should be eliminated(at 23:00). He gives the example of Electromagnetism where by the equation
$\epsilon_0\mu_0 = \dfrac{1}{c^2}$
one can eliminate $\mu_0$. According to him,... |
I am a bit confused on how GTR uses intrinsic curvature instead of extrinsic curvature. Maybe it is just a misunderstanding, but I will do my best to describe my question:
If we take an object of $n$ dimensions and want to bend it, we need $n+1$ dimensions. This can be seen if we take a sheet of paper (which we simplyf... |
If large mass causes a curvature around spacetime, then why don't we see a gravity lens around our planets?
|
So, Coulomb's Law states that $F_e = k\dfrac{q_1q_2}{R^2}$, where $F_e$ is the force of attraction between two charged particles of magnitude $q_1$ and $q_2$, where the distance between them is $R$. $k$ is Coulomb's constant here.
In SI units, $k$ has some dimensions whereas in CGS/Gaussian units, it doesn't. This woul... |
Suppose there is a huge world in our universe and their laws of physics is the same as ours. Humans are like atoms compared to that world. In that world a double slit experiment is being performed by an observer where instead of electrons humans are fired through a narrow slit.
So when humans are fired will the observ... |
I'm trying to explain Bernoulli's principle (in the context of flight) to an audience that doesn't have a physics background. So I'd like to avoid mentioning technical concepts as much as possible.
The part I'm specifically struggling to explain is why an increase in air velocity necessarily results in a decrease in ai... |
I think it is correct because:
v = displacement/time, if the direction changes, the displacement changes so the velocity is not constant anymore.
Please correct me if I'm wrong
|
In axiomatic QFT, the defining property of a scalar field $\phi$ is that it does not change under a Lorentz transformation: that is, "If $U(\Lambda)$ is the unitary representation of a Lorentz boost $\Lambda$, we have $U(\Lambda)^\dagger \phi(x) U(\Lambda)=\phi(\Lambda^{-1} x)$." Call the quoted part Statement A.
In La... |
The question refers to the well-known phenomenon of dynamical localisation due to an oscillating electric field, as explained in Dunlap & Kenkre, PRB 34,6 (1986). Here, a particle initially localised to a single lattice site will remain localised if the ratio of field amplitude to driving frequency equals the root of t... |
The title may be a little confusing, so let me clarify the question.
In the simple 1D problem of a quantum particle in (finite) well, the allowed energy eigenvalues for bound states are quantized due to continuity constraints on $\psi$ and $\psi'$. However, above a certain energy ($V_0$ the height of the well), the ene... |
When there is a battery connected in an open circuit, there is some induced e.m.f, right?
Now, if a battery is connected across its ends with a wire, with no resistances or any other appliances, and adding that the battery is perfectly ideal with no internal resistance, then still, there will be a current through the w... |
In the image shown below the an iron plate is dividing the cylinder into two halves with 15 meter and 1 meter respectively.
The area of the cylinder is 0.196 m(sq).The liquid inside the cylinder is water.Height of the cylinder is 16 meters.
We know that the
Pressure = density of water X acceleration due to gravity X he... |
I'm trying to understand a passage from the paper "Gaussian operator bases for correlated fermions", J. F. Corney and P. D. Drummond (https://arxiv.org/abs/quant-ph/0511007), specifically going from the first to second line of Eq. (2.5), which is about Gaussian density operators:
The operators $\hat{b}_i$ are fermioni... |
The frequency dependent electric conductivity in the Kubo formalism is given as: $\sigma^{\alpha \beta}(r,r^{'},w)=\frac{ie^2}{w}\Pi_{\alpha \beta}^{R}(r,r^{'},w) + \frac{e^2n(r)}{wm}\delta(r-r^{'})\delta_{\alpha \beta}$. where $\Pi^{R}_{\alpha \beta}(rt,r^{'}t^{'})=-i\theta(t-t^{'})\langle[J_0^{\alpha}(r,t),J_0^{\beta... |
Consider the following hamiltonian for non-interacting phonons and fermions
\begin{equation}
H = -\sum_{i} \mu c^\dagger_{i} c_i + \frac{1}{2} \sum_k (\pi^2_k + \omega_0^2 \phi_k^2) \tag{5}
\end{equation}
where $\pi_k$ is the canonical momentum conjugated to $\phi_k$, $$[\phi_k,\pi_{k'}]= i \delta_{kk'} .$$
How do I d... |
At zero temperature, the entropy of generic systems need not vanish, but often seems to in practice. I would like to know some concrete examples where $S\neq 0$ at $T=0$.
A very high-energy flavored scenario where $S\neq 0$ at $T=0$ is the case of extremal black holes, where $S=\frac{\rm Area}{4G_N}\neq 0$. I believe... |
I am not a mathematician, so I really appreciate it if someone could explain it in a simple way. In Rydberg Atoms book by Thomas F. Gallagher, the Schroedinger equation for the H atom in atomic units is written as:
$$(-\frac{\nabla^2}{2} - \frac{1}{r})\psi=W\psi$$
If we assume that this equation is separable and write ... |
I was reading these lecture notes and they show how if you start with two operators $p$ and $q$ such that $[q,p]=i$, you can define $a:=\frac{1}{\sqrt{2}}(q+ip)$ and $a^\dagger:=\frac{1}{\sqrt{2}}(q-ip)$, such that $[a,a^\dagger]=1$, and that this in turn implies that these are bosonic ladder operators. This left me wi... |
I know how to calculate centroids in single integrals and double integrals and derive the formula for center of mass, but I don't know why the center of mass is defined by $\text{mass}_1 \times \text{distance}_1 = \text{mass}_2 \times \text{distance}_2$. I can't find any site that can explain this.
|
The interplanar seperation for orthorhombic crystals is found in most books on introductory solid state physics (e.g. Kittel). I searched for interplanar seperation for other crystals(hexagonal,triclinic etc), and found a list of formulas in the wikipedia page for Crystal structure. Where can I found derivation of such... |
a pellet gun fires ten 2.14-g pellets per second with a speed of 483 m/s. The pellet is stopped by a rigid wall. Calculate average force exerted by stream of pellets on the wall?
So, in the solution key for this question, they do
$$ F_{avg} \cdot 1 = 2.14 \cdot 483 \cdot 10^{-3} $$
But, I'm confused why one second is... |
How do we know that any two points of an ideal wire must be equipotential whether or not there is a current flowing through it?
I fully understand that how the electric field in a conductor in electrostatic condition will be zero. My question is primarily for a conductor which is not an electrostatic condition.
In any ... |
In Peskin and Schroeder's QFT book they give
\begin{align*}
H &= \int d^3x\int \frac{d^3p d^3 p'}{(2\pi)^6}e^{i(\mathbf{p+p'})\cdot \bf x}\left\{-\frac{\sqrt{\omega_{\bf p}\omega_{\bf p'}}}{4} (a_{\bf p}-a_{\bf -p}^\dagger )(a_{\bf p'}-a_{-\bf p'}^\dagger) +\frac{-\bf p \cdot \bf p' + m^2}{4 \sqrt{\omega_{\bf p} \omega... |
In the concluding section of this post user Chiral Anomaly states following:
On the other hand, since any stable marriage of quantum theory and gravity (in the sense of general relativity, not just Newton) is necessarily highly non-local, even in its causal structure, the door seems to be open for non-quantum theories... |
From the formula of circular aperture we get:
sinθ=1.22λ/D
But according to this formula, the θ is the angle on the side of the Airy disc formed.
The formula for angle of resolution for a human eye seeing a hair on the ground or seeing 2 stars through a telescope is also the same, ie:
sinθ=1.22λ/D
But in the case of t... |
Sorry for the relatively long post! Thank you for reading and let me know if there is anything I can clarify/fix.
My textbooks defines Work in the following way:
A measure of the amount of energy transferred between two systems.
Positive work is performed by a system when the force it generates has a component in the ... |
In Newtonian Physics the general equation for the acceleration when there is a central force is $$\frac{d^2\vec{r}(t)}{dt^2}=\frac{1}{m}\frac{\vec{r}(t)}{\left|\vec{r}(t)\right|}f(\vec{r}(t))$$ with $m$ being the mass, $t$ being the time, and $\vec{r}(t)$ being the distance vector as a function of time. $$\frac{d^2\ve... |
In the Maxwell's demon thought experiment, initially, the gases in both boxes have the same temperature. The devil uses the door in the middle to allow the fast (hot) molecules on the left to pass to the right. But, we said the gases in both boxes have the same temperature. So, the right box is not completely hot. Ther... |
Here is a question that was given by my instructor.
We have to find current in branches of circuit.
Now I simply calculated the line integral of driving field along the closed loop ABCA and ADBA as shown in my solution picture.
Now line integral of field along a branch of a circuit (example AC) equals 3i (i is the curr... |
I've recently watched a video from Rice university, (https://www.youtube.com/watch?v=w1d0Lg6wuvc&t=3s) where they used an electric field to remotely stimulate CNTs to form a wire. This wire was able to draw electricity directly from the field and could power 2 leds all by itself. This interested me, but I want to know ... |
How do you figure out what the stress equations are? How do you find a solution to the stress equation?
|
In the context of diatomic molecules I have seen it has come up that an eigenvalue $M_L\hbar$ of $L_z$ is doubly degenerate with respect to reflection about a plane containing the $z$ axis, whose corresponding operator I shall call $A_y$, since $A_yL_zA_y = -L_z$. Therefore one chooses the basis of $L_z^2,A_y$ instead ... |
I’ve been reading an article about the matrix element of the three different channels In Feynman diagrams and I saw this. My question is how did $k^2 - m^2$ (part of the fermion propagator) become $2p2*p4$ in the photo?
|
I just finished reading the excellent book that is "Physics from Symmetry" by Jakob Schwichtenberg.
I am left with a doubt. In the book he starts with a group theoretical introduction and clearly shows how we can see the Lorentz group as two copies of the $SU(2)$ group and derives all the Lagrangian and equation of mo... |
I was thinking about the explanation for how the Moon gets tidally locked with the Earth. We are working in the non-rotating reference frame of the Earth, and assume it is inertial (to an approximate degree). I was looking at the explanation given in this link (see 2nd and 3rd paragraphs).
Because tidal forces of gravi... |
Given the Hamiltonian:
$$H = \frac{1}{2m}p^2 + x_i M^{ij} x_j.$$
Is there an exact non-relativistic propagator for this, where $M$ is a general symmetric matrix? Similar to the harmonic oscillator propagator. I expect it might be able to be done by diagonalising $M$ or a change of variables but I'm not really sure if t... |
In the infinite momentum frame in $11$ dimensions, if we do a large boost along the $x^{11}$ direction, the total mass shell energy $E$ can be shown in a non relativistic approximation to be $ E - p_{11} = \frac{p_{\perp}^{2}} {2p_{11}}$ (massless case) where $p_{\perp}$ is the transverse momentum. However, I don't und... |
Non-physicist asking.
Note: I see that there are similar questions but none that I can find that addresses this specific query.
Exaggerated diagram
Question
If the two beams of light leave the source at the same time, what happens?
(a) they arrive simultaneously at the viewer with the wavelength shifted
(b) they arri... |
My Level/Background:
I have just completed my first year of undergrad. In high school, I completed AP Physics C Mechanics and Electricity and Magnetism. In my first year of undergrad, I completed a course on Newtonian Mechanics and a course on Special Relativity and Electromagnetism which both approximately followed th... |
Twisting one end of a ribbon causes the ribbon to want to twist back. So if spacetime is connected, and we can fix the ends of spacetime at our observable universe's ends so to speak, is there some analogue to spacetime experiencing tension when planets revolve?
(I am thinking that revolving matter-energy curves or dra... |
I'm learning differential equations and waves - following online courses and reading some textbooks - and I find that quite often, the use of Phasors, equations combining sinusoidal waves of different amplitudes and frequencies (the derivation of beats)...etc...they're explained really briefly, without a lot of diving ... |
At school we are doing an experiment with a setup involving a vertically positioned ruler, a marble and a light gate. The method requires us to drop the marble from various heights on a ruler (in 4cm increments) into the light gate and record the resulting speed of the falling marble in m/s. (Light gate was positioned ... |
I've been scouring physics for non-associative situations, particularly where study of quasigroups and loops might come in handy (they always seem to be left out). The poisson and lie brackets form a Moufang loop, but I rarely see it more than one deep where the structure starts to show. It's common to see $\{x, y\}$... |
Usually we write the Yang-Mills theory with gauge group $G$ as
$$\frac{1}{g^2} \mathrm{Tr}_{R} (F\wedge \star F)$$
But here we need to choose what $R$ is. There are several cases one may expect:
$R$ has to be the rep with minimal dimension. Different choice of $R$ gives different gauge theories. For example, for $\rm ... |
Consider two consecutive boosts in $2+1$ dimensional spacetime, the first along the $x$-axis and the second along the $y$-axis. The net transformation is $$B_y(\theta_2)B_x(\theta_1)=\begin{pmatrix}
\cosh\theta_2 & 0 & -\sinh\theta_2\\
0 & 1 & 0\\
-\sinh\theta_2 & 0 & \cosh\theta_2
\end{pmatrix}\begin{pmatrix}
\cosh\th... |
Most of the pictures I see on the internet on electromagnetic waves, show two prependicular constant sinusoidal waves made of electric and magnetic fields. Shouldn't the magnitude of at least the electric field decrease as distance increases by the inverse square law? It is as if you would feel the same electric force ... |
According to EMI definition, it is the changing magnetic field acting ON the conductor that induces an emf. However when using Faraday’s law, instead of finding the changing magnetic field acting on the conductor we find the changing magnetic field in the space enclosed by the conductor. Why?
|
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