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When we use canonical quantization method to quantize a free real scalar field in Schrodinger Picture.
The free real scalar Lagrangian is
$$\mathcal{L} = \frac{1}{2}\partial_\mu\phi\partial^\mu\phi - \frac{1}{2}m^2\phi^2$$
The EOM derived from this Lagrangian is
\begin{align}
(\partial_\mu\partial^{\mu} + m^2)\phi = ... |
I am a high school student. My query is that I have read somewhere that orbital angular momentum is related to the motion of the electron or any subatomic particle (I know that this is not the same as in classical mechanics). I want to ask the following: In $s$ subshell i.e for azimuthal quantum no. $l=0$, the orbital ... |
No doubt we've all read quite a bit about amplituhedra in recent years, the best thing since sliced bread apparently for obtaining scattering amplitudes. But finding on the web formal definitions of it have seemed to me surprisingly elusive, and in fact I don't recall ever seeing any.
So can it be readily defined expli... |
Mathematical side of the problem
Given the metric
$$ds^2 = dr^2+r^2d\theta^2+r^2\sin^2\theta d\varphi^2$$
we can easily construct the action of a free particle
$$S=\alpha \int d\tau \underbrace{\sqrt{\dot{r}^2 + r^2 \dot{\theta}^2+r^2\sin^2\theta \dot{\varphi}^2}}_{:=L},\quad \text{where}\quad \dot{\vphantom{r}}:=\frac... |
I am familiar with Pseudo forces and how we use them in accelerating reference frames. My question is a bit specific. Let’s say I am accelerating at $a\frac{m}{s^2}$ and holding a tennis ball of mass $m$. I understand it is the push force provided by my hand that is accelerating the ball with me. When I observe the bal... |
In string theory, consider the following variation of the worldsheet coordinate $$\delta z = \epsilon(z)$$ This induces the following variation in the target space coordinates $$\delta X^{\mu} = \epsilon(z) \partial X^{\mu} \equiv V^{\mu}$$ Now, shouldn't this induce a variation in the target space metric (Minkowaski m... |
I was trying to solve padmanabhan's problem "Show that the cross-sectional area of a parallel beam of light is invariant under Lorentz transformations." [Hint. Argue as follows: if $k^i$ is the null four-vector along which the light beam is traveling, the cross-sectional area is defined by two other purely spacelike ve... |
When deriving the Euler-Lagrange equation my notes bring the $\delta$ into the action integral, which is fine, which gives
$$\delta S=\int_{t_0}^{t_1}dt \frac{\partial \mathcal L}{\partial q_i}\delta q_i+\frac{\partial \mathcal L}{\partial \dot q_i}\delta \dot q_i \tag{1}.$$
We then use the fact that the time derivativ... |
Could somebody check whether my understanding of this experiment is correct, because I feel like I assume Maxwell's results.
When a spark forms across gap, a spark is also created across the receiving loop. Since the current is ac, an electric field is produced that oscillates with the current, which causes the electr... |
Does it mean that there can be no flow of charge or does it mean that the substance can not have any excess charge on it?
|
In PCT, spin and statistics, and all that book, the following example is given:
Let $S(A)$ be a representation of $SL(2,C)$ given as :
$$S(A)=\frac{1}{2}\left(a^{0} \mathbf{1}+\mathbf{a} \cdot \mathbf{\sigma}\right)\left(1+i \gamma^{5}\right)+\frac{1}{2}\left(\bar{a}^{0} \mathbf{1}-\overline{\mathbf{a}} \cdot \mathbf{\... |
We know that the lower the momentum a particle has the higher will be its de Broglie wavelength, so is there any upper limit to the de Broglie wavelength of electron or any other particle due to the zero point energy of vacuum which prevents further reduction in momentum?
|
Suppose we are given a sphere with total charge $Q$ and radius $R$. To find the total charge $Q$, we can use the relationship $$\rho = \frac{dQ}{dV}\implies Q=\int_0^R\rho \cdot dVdr$$
where $dV$ is the derivative of volume with respect to $r$, the distance from the center of the sphere, and $\rho$ is the volume charge... |
Is it possible that apart from positive and negative charges, there is a third kind of charge that we have somehow, not discovered yet?
If not, is there some proof of the existence of only two types of charges?
|
In the problem, a cavity is taken out of a uniform conducting sphere. Inside the cavity, a dipole is placed as shown in the fig. find the potential at point P
|
How fast in mph is water when released from dam, at point of exit , as a baseball is clocked in mph when released from a pitchers arm .
I am a complete novice and looked all over for an answer
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What wavelength De Broglie relationship represents, if particle's motion is given by its group velocity (which is superposition of waves of many wavelengths)
|
I'm following a derivation here of a carnot-cycle
and I'm stuck at
$ T_3 / T_1 = T_4 / T_1 = (V_1 / V_4)^{(κ - 1)} = T_3 / T_2 = (V_2 / V_3)^{(κ - 1)} $
I don't get that. Is that due to mathematical reasons or is there a physical meaning behind it?
|
Does anybody know how to compute the Berry curvature for a spin with angular momentum $s$ (so it's not the usual derivation you find for spin-$\frac{1}{2}$ particles in most textbooks) in a magnetic field $\vec{B}$ pointing in an arbitrary direction and playing the role of the parameter on which the Hamiltonian $\hat{H... |
Isham in his Lectures on Quantum Theory, Chapter 5, General Formalism of Quantum Theory, Section 5.2.1 makes states the following two assumptions for quantising a classical system.
Q1 The quantisation procedure is linearity preserving, i.e., the quantisation map $f\mapsto\hat{f}$ is linear, so that $$r_1f_1+r_2f_2\map... |
My background is not in meteorology, but I am interested in climate models of tidally-locked planets of red-dwarf stars. I recently found a great review of different conditions on such planets modeled by 3D GCM models in Chen et al. 2019. Among other things, I was trying to extract information about the precipitation i... |
I don't know enough about the subject to know that I am wrong.
|
We say the cosmic microwave background radiation “has a temperature” of 2.7K.
Does this mean it has a temperature in the way we say the air around a warm lightbulb has a temperature of 120° or in the sense that the mix of electromagnetic waves given off by the lightbulb are like those emitted by a blackbody at 3000K?
I... |
I saw a problem, and saw that it could be easily solved using conservation of mechanical energy. So I wrote my equation:
$$mgh_1 + \frac12mu^2 = mgh_2 + \frac12mv^2$$
Where $u$ is initial velocity, $v$ is final velocity, $h_1$ is the initial height ,$h_2$ is the final height and $m$ is the mass.
But what do I do if th... |
Now I known the spectrum function can be measured directly in certain experiments. Suppose Hamiltonian for a system is $H = \epsilon(k)\sigma_x+M(k)\sigma_y$,spectrum function can be calculated as:$A(k,\omega)=\sum_{n,\sigma}\frac{|u_{n,\sigma}(k)|^2}{\omega-E(k) + i*\Gamma}$,where $E(k)$ and $u_{n,\sigma}(k)$ are eige... |
I read this statement in my textbook (here)
Charge is not only a scalar (or invariant) under rotation; it is also invariant for frames of reference in relative motion.
I am not able to understand what this statement means.
Besides, is it always true for every scalar quantity?
|
After reading the article about the Twin Paradox from: Griffiths, David J. (2007) (see pdf on internet)
I got some questions.
There are two frames A and B.
B moves to the right with velocity $v$.
Star X is to the right of A at a fixed distance $L$.
Premises: $c=1$, $v=\frac{4}{5}$, $\gamma =\frac{5}{3}$, $L=12$, A an... |
My understanding is that although we are taught that solar cells only absorb photons of energy higher than the bandgap of the material, some of the sub-bandgap photons still gets absorbed, which is evident when looking at the absorption coefficient spectra (it is not zero where it is below the bandgap).
First, am I cor... |
Materials:
26mm Dia x 35.2mm FL, Grade 1, Plano-Convex Lens. PicoP laser picoprojector.
The problem:
I've got a question about using a lens to parallelise light rays coming from a laser projector.
The projector is noted to be in focus at any distance from the wall upon which you project, and as far as I've seen this is... |
Given two sets of unit norm real vectors $S_1$ and $S_2$ with the same shape(both of them are $d\times d$).
One can get solid angles $SA(S_1)$ and $SA(S_2)$ out of them.
Since there are many lectures on how to compute the $SA: R^{d\times d}\to R$ and it's hard to do so.
And I'm interested in is there any easy way to ... |
I am trying to get a firm understanding of crystal structures in solid state physics but having some issues with the terminology.
If I understand correctly, the lattice are points in a 3-D space so that each point has an identical surrounding. Does this mean the points on a lattice form the unit cell and the basis for... |
I've read a lot about ultrasonic ranging (measuring distance with an ultrasonic sensor), but I haven't been able to determine why such methods only work in the ultrasonic range. Why not infrasonic? Or audible range? Since were just dealing with sending out waves and measuring the time it takes to come back, why can't w... |
Suppose a particle, say a positron is moving with initial velocity ${\bf v} = (c/3,c/3,c/3)$, where $c$ is the speed of light. Then the relativistic momentum is ${\bf p} = \gamma m{\bf v}$. Now suppose we apply a force, perhaps due to an electric field E $=(0,0,E)$, so the force is F$= (0,0,eE)$.
In Newtonian mechanic... |
When studying about metal-insulator transitions, I was wondering which material properties can give direct information about this phenomena. Also, what information can be derived from these properties. I cannot seem to find any good readings about this topic. One last thing: which type of materials are useful in experi... |
You hang a rapidly spinning top on one end from a string and let it go. It doesn't fall. It rotates around the point where it is hung from the string. Mathematically, I understand it. Angular momentum is changed by torque, which is moment arm cross force. So vertical gravity produces a horizontal change in angular... |
Two dimensional creatures living on the surface of an inflating 2-sphere are often used to explain general relativity, curved space, and big bang cosmology. For years, though, I have wanted to ask: The 2-sphere is closed. What about the actual universe? Is it closed in the same sense? When cosmologists talk about a... |
In general for some smooth and bounded $\hat{V}$
$$
\left[\hat{V}(t_1), \hat{V}(t_2) \right] \neq 0 \text{ if } t_1 \neq t_2
$$
But what more can be said about commutators of this type? I am particularly interested in the case where the two times are "not far apart", say
$$
|t_2 - t_1| \leq \epsilon
$$
for some suffici... |
If I apply $5\mathrm{N}$ force on a object for $2$ seconds, can I say that I applied $10\mathrm{N}$ force?
|
In Zemansky & Dittman: Heat and Thermodynamics problem 5.8 (3rd edition, page 135) is the following
$\bf{5.8}$ The temperature of an ideal gas in a tube of very small, constant cross-sectional area varies linearly from one end ($x = 0$) to the other end ($x = L$) according to the equation
$$T=T_0+ x\frac{T_L-T_o}{L}... |
If I put container of compressed air into a Coolgardie Safe, and brought the temperature down by say 3°C, how am I supposed to calculate the temperature of the air after it is decompressed back to ambient air pressure?
I'm not asking for calculations, I'm asking for formulae and theories which I can use here.
|
I have simulated a plane wave in a Finite Element solver. Starting from the general acoustic wave equation $\partial u^2/ \partial t^2 = c^2 \nabla ^2 u$, the weak form is
$a(u,v) = \int_{\Omega} (v u^{n+1} + c^2 \Delta t^2 \nabla v \nabla u^{n+1})dx$
$L(v) = \int_{\Omega}(2u^{n} - u^{n-1})vdx$
where $u$ and $v$ are ve... |
For example, in quantum mechanics, the commutator of the position and momentum is $$[\hat{P_i} ;\hat{Q_j} ] =i\hbar\delta_{ij}\neq 0, i\neq j$$
I know that the position space representation of the wave function is the Fourier transform of the momentum space representation. From what I know, this also applies for other... |
Suppose we have the $S'$ frame moving at some velocity $v$ in the $X$ direction relative to the $S$ frame, then it follows
$$x' =\gamma (x+vt), t'=\gamma(t+\frac{vx}{c})$$
From my understanding, to get the inverse Lorentz transforms, we say that if $S'$ is moving at $v$ relative to $S$, then $S$ is moving at $-v$ rela... |
In some textbooks, the Maxwell equations are stated in a very simple mathematical form (up to multiplicative constants coming from the system of units being used):
$$ \begin{array} \mbox{d}F =0, \\ \delta F = j, \end{array}$$
where $d$ and $\delta$ are the exterior differential and co-differential on Minkowski spacetim... |
I've been reading some literature on opinion dynamics models that aim to describe how agents' opinions change after interacting with each other. A classical model (from this paper) for describing how agent $n$'s opinion, denoted by $x_n(t)\in[0,1]$, moves closer to agent $m$'s opinion, denoted by $x_m(t)\in[0,1]$, is a... |
While reading a book on photonic crystals, I came across the Electromagnetic Variational Principle. If the electric and magnetic fields are represented by the real part of
$$\mathbf{H}(\mathbf{r}, t)=\mathbf{H}(\mathbf{r}) e^{-i \omega t} ,\mathbf{E}(\mathbf{r}, t)=\mathbf{E}(\mathbf{r}) e^{-i \omega t} $$
the lowest... |
In ordinary beta decay, an electron and an anti-neutrino, together with a proton, are emitted. The proton has zero lepton number, the electron +1 lepton number, and, it is said, the neutrino-type particle has -1 lepton number, so is an anti-neutrino. Is there any independent experimental reason for deciding that it is ... |
So I have just gone over a lecture on electron dressing whereby an electron dresses itself in a foam of electrons/positrons/photons through photon emission and absorption (see image).
My lecturer says something that I interpret to be along the lines of:
Probing with a photon with low $q$ (momentum) means you see all... |
I am new to spinor notation and I came across the following matrix:
What operator has the following form when expressed in matrix spinor notation;
$[[W]]=\frac{\hbar \xi}{2} \begin{pmatrix}\hat L_z & \hat L_x-i\hat L_y\\ \hat L_x +i\hat L_y&-\hat L_z\end{pmatrix}$.
Any help with this is appreciated.
|
In Statistical Physics, part 2 by Landau and Lifschitz, second 22, it's written that the sound wave only has longitudinal direction of polarization in liquid while both longitudinal and tranverse in solid.
My question is why there is such a difference in liquid and solid. Which feature cause this difference?
|
When comparing a classical and a quantum string, the resulting wave function is made up of the sum of the individual modes for the former but the product for the latter. That is at least what I gather from a lecture on quantum field theory, cf. particularly the slide at minute 5:07. The narrator says that
[Unlike the... |
How should I determine the direction of the force in the given case: (p is the electric dipole moment)
Using the following formula
My book has the following :
I am unable to understand the given correlation between the direction of Force and the formula. I am confused with the gradient of E and it's dot product (cor... |
Anyone know what the standard texts and papers are for understanding how modern ie numerical weather forecasting is done?
|
I was reading a book on Solid State Physics which stated that insulators have a band gap larger than 3eV, insulators <3eV and metals have no gap. It also states that semiconductors become insulators at absolute zero. However, at 0 K the band gaps for semiconductors remain very low (1.4eV for example) and barely change ... |
We can clearly read in the first section of this chapter,
An inductance is made by winding many turns of wire in the form of a coil and bringing the two ends out to terminals at some distance from the coil, as shown in $\textrm{Fig.} 22–1$. We want to assume that the magnetic field produced by currents in the coil doe... |
There are multiple proofs of the Aharonov-Bohm effect. Arguably the most simple proof is the original one by Aharonov and Bohm which appears to be proven by inspection. Two other methods I have seen use the machinery of the Berry phase and the path integral. I was wondering whether it is possible to derive the effect u... |
If I'm getting punched by a fist that is moving at a constant velocity (let's say $20 \mathrm{m/s}$), I still feel a force that is being applied to my body. However, according to $F=ma$, in order to feel a force, the object needs to be accelerating. Then, how can a non-accelerating object apply a force to me?
|
We've all been taught that dark surfaces heat up faster, since they absorb photons, while light surfaces heat up slower, and reflect photons. But I can't reconcile this with momentum transfer.
When a photon is reflected off a light surface, more momentum is transferred to the surface, since it's a nearly elastic collis... |
I am looking for an answer from AdS/CFT perspective in 2+1D.
If there is a discrete bulk geometry rather than continuous, is it possible to have CFT on boundary with discrete symmetries?
Can we have a consistent description of CFT with discrete symmetries ( discrete translation, rotation etc) on boundary as holographi... |
I've heard that General Relativity entails matter (or mass) is necessary for time to exist. However, there are vacuum solutions where the universe is empty of matter but still has spacetime.
P.s: I'm not necessarily talking about proper time. I'm referring to time in general.
|
I've been watching an MIT course which explains the way that a nuclear bomb works. I am not a physicist or physics student, however; I am a computer scientist. As such, I am not looking for a level of detail as required from someone who studies physics. I also had a look at this question From what I understand so far c... |
It has been stressed out in the books that I've consulted that, for an intrinsic semiconductor, $n=p$.
However, with this in mind, they also derivate the following equation:
$$E_{F_i}=\frac{E_c+E_v}{2}+\frac{3}{4}k_BT\ln\left(\frac{m^*_h}{m^*_e}\right) \quad\quad\quad\quad (1)$$
Which would be the Fermi energy level of... |
Every good textbook says that the reduction potentials of half-reactions are all relative. There is no absolute standard, so the conversion between hydrogen gas and aqueous 1M hydrogen ion at a platinum electron is used.
However ... a voltage can readily be converted into a free energy. So what happens if you take yo... |
It is well known that if two operators commute, the it is possible to find common eigenfucntions for them. What if we have 3 operators that commute with each other? Will we find common eigenfunctions for all of them at the same time?
|
Natural integral (as we will define it) is a distinguished antiderivative of a function that can be understood as interpolation of the sequence of consecutive derivatives to the $-1$. It has a naturally defined integration constant. While it is possible to define natural integral in various ways, it all boils down to t... |
In scattering theory, the resolvent, $S$-matrix, $T$-matrix, etc. are formally defined for any complex energy, $z$, even if most practical calculations consider just the positive real energy axis, $z=E$. One such practical calculation is in partial wave analysis of finite-range central force scattering problems, where ... |
For anholonomic system, i.e. Gravitation Eq. 9.22
$$[e_\mu, e_\nu] =c_{\mu\nu}^\alpha e_\alpha$$ where $$[e_\mu, e_\nu]\neq 0$$ for some $\mu,\nu$,
the states of the system dependent on its path.
Question 1.a: However, is it still possible to construct some sort of geodesic equation for the anholonomic system? i.e.
$... |
What are the best locations for placement of $y$ supports for a beam of length $x$?
This seems like a very basic physics question, but I have been unable to find the answer. Perhaps I am not sure what terms to use to search.
For example, let’s take a $4\times 4$ piece of lumber of length $x$.
For $y=1$, the answer is o... |
What is the physical interpretation of the electronic band structure diagram and wave vector $k$ in solid-state physics? Does $k$ tell something about the direction of moving electron/particle?
The wavevector $k$ is a Fourier transform of position $x$. Can we tell that at a specific point of $k$ the electron will be a... |
When we move forward in a car, things around us move backward. I understand some force is being applied on the car that is the reason for its forward movement. But what is the source of force on the things moving backward that we see when moving forward? If I am accelerating, things outside my car are also accelerating... |
I am reading "Quantum Chance" by Nicolas Gisin. I would like to know how to calculate the Bell Game outcome given in the following section of the book.
BACKGROUND
The Bell Game begins with a pair boxes. Alice and Bob each have a box with a joy stick that can move either left or right. This leads to four combinations of... |
I've made an error in my thinking somewhere concerning gravitational waves in the following thought experiment, and would appreciate knowing where I went wrong:
Consider two overlapping gravitational waves, with regions both ahead and behind the overlapping area. Relative to a far away observer, the overlapping area wo... |
Can we just say that if between 2 points in some given circuit, there's no load, then the potential at those 2 points are same?
|
Currently I am doing some simple simulation of 1D Transverse field Ising model. I map the quantum mechanical problem into classical 2D classical Ising model with different horizontal interaction and vertical interaction so that the simple Monte Carlo sampling (local update) can be implemented. But I have a problem that... |
If electrical, and economic limitations are ignored, would it be possible for a civilization to mass produce many millions of tonnes of useful heavy elements using particle accelerators?
Could they use protons, or hydrogen/helium in a super collider to work their way up the fusion chain to any desired element, or woul... |
I know that when air is heated it expand, and thus it makes density decrease, pressure increase, and temperature increase. But, why hot air cools off when it expands and rise ?
Please answer with a long sentence.
|
There was a Leonard Susskind lecture on the Higgs Boson I watched the other day, and he talked about graphing the field where the domain was some sort of field space. The lecture is here at about 6 min: https://www.youtube.com/watch?v=JqNg819PiZY&t=350s
But this idea seems bizarre to me. I have some sort of conceptual ... |
I tried to find out how to calc it myself, but seems it's not something very straigthforward... I hope it's not a bad question, sorry if it is!
So, this is known:
It's 99mTc
Let's assume it's point source
It's the gamma radiation
A = quantity is 50 MBq
E = photon energy is 140 keV
R = distance is 10 cm
I think I also... |
Isham in his Lectures on Quantum Theory Chapter 6, Technical Developments states that for a mixed state $\rho=(\psi_1,\dots,\psi_D;w_1,\dots,w_D)$ and an observable A with an eigenvalue $a_n$, $$\text{Prob}(A=a_n;\rho)=\sum_{d=1}^Dw_d\text{ Prob}(A=a_n;|\psi_d\rangle),$$ based "on the assumption that that quantum-mecha... |
We know the tidal waves are decreasing the spin rate of the earth which causes the days to longer, so as the angular momentum of the earth decreases it means it rotational kinetic energy also decreases since energy is always conserved the translational kinetic energy of earth must increase now right? Then that would ca... |
Consider the standard arrangement in special relativity. Let $S'$ move in the positive $x$-axis with a velocity $V$ with respect to $S$
Question: $S$ then moves with a velocity $-V$ with respect to S'. Is this an assumption or a theorem of special relativity?
If theorem - How can it be derived? If assumption - Why is i... |
Why is electric flux defined at all? It seems that without having symmetry in objects, we cannot use it to find something important. Please shed some light on its history also.
|
In a JRE podcast from a few years ago, talking about the idea of a universal constructor, Sam Harris said that we could go to a near-vacuum area of deep space, collect nothing but hydrogen atoms, build a fusion reactor, create heavier elements, and based on those elements, create a universal constructor and then build ... |
All right. Here's what I understand about axial turbines:
It is an axial compressor in reverse.
An axial compressor forces air to flow in an increasingly tight space, where there is not enough pressure gradient (due to the high pressure combustion chamber beyond) for Bernoulli's effect to speed up the flow and choke... |
If you compress liquid in an infinitely stiff and infinity insulated cylinder such that the cylinder does not expand and no heat can transpire, how much of the energy will converted to increase in pressure and how much will be converted into increase in temperature?
This is something that J.P Joule himself documented h... |
Why the force exerted by a thin soap film is on a movable wire of length L is $2TL$ where $T$ is the surface Tension of the liquid? Why is there a factor of $2$? I can't understand it because there are many many layers between the two outermost layers and they should also exert a pulling force on the wire.
The movable... |
For a two-level system having an arbitrary state, $\Psi=c_1(t)|1\rangle+c_2(t)|1\rangle$ the transition probability from state $|1\rangle$ to state $|2\rangle$ ,i.e., $|c_2(t)|^2$ can be calculated from the rate equations:
$i\dot{c_2}=(\Omega/2)e^{-i(\omega-\omega_{21})t}c_1$
$i\dot{c_1}=(\Omega/2)e^{+i(\omega-\om... |
It is clear from a Lagrangian formalism, that various types of symmetries of a system give rise to many interesting conserved properties of the given system but is there an interesting physical intuition behind? Is there some sort of physical discussion that can be had about why symmetries would intuitively conserve an... |
There was a section of my textbook that mentions this and I can't understand it...
Q: Is static electricity caused by friction?
A: No. It appears when two dissimilar insulating materials are placed into intimate contact and then separated, they get charged and all that is required is touching. It is only that the proc... |
The question arises from the fact the voltage provided across battery terminals is constant no matter how much current is drawn (for non-ideal batteries the current draw is limited but still can be varied over a range).
EDIT:
Voltage is basically the potential difference or the energy required to displace a charge aga... |
There are two torque equations :
$$\tau = I \alpha \tag{1}$$
$$\tau = F r \tag{2}$$
In the second equation, we imagine that $F$ is applied at $90°$, and that $I = k m r^2$. ($k$ is the constant responsible for the shape and the axis)
Then by equating those two formulas, we can get that: $$\alpha = \frac{k \omega}{t}.$... |
I would like to know some about the physics of an interesting material, the sepiolite. I mean the material from the Wikipedia article Sepiolite where are explained the general and identification characteristics in the right column, and its applications. The motivation of this question is that I'm interested about the m... |
We have suspended an electrically neutral metallic ball from an insulated string between two parallel metallic plates that are oppositely charged but have the same magnitude. So, the charge in this system is conserved.
We put the metallic ball in contact with one of the plated (any one of them) and then leave it to mo... |
Suppose a point that emits light in all direction. Some of the light rays hit a sphere and create circular shading on the sphere (in the figure, the shading is exaggerated a little through posterization). Is there a single line that goes through the point light, the centers of all the shading circles and the center of... |
Metric = (-+++), complex $i$'s are ignored.
Using the following decompositions of the Poincaré generators,
I can write the Poincaré algebra as
I can get the Galilei algebra using the following redefinitions,
and then taking the limit $c\rightarrow \infty$
The centrally extended Galilei algebra is the Bargmann al... |
Let's assume that a conducting element is kept on a table (to indicate that no power source is connected across its ends). So, all the electrons move in random directions and repel each other. The question I have is "Why do they not fly away?"
I think that they don't have enough energy to escape the strong pull of the ... |
The Feynman diagram for the decay $\phi \to K^+K^-$ usually depicts two gluons. (This can be seen e.g. on Wikipedia).
Why do we need two gluons, instead of just one?
|
I am not a physicist and I've recently started watching introductory lectures on QM on youtube (MIT, Stanford) and reading the Feynman lectures. I have a high-school level knowledge of Math so I'm not good (yet?) with equations. I'm pointing this out because I'm looking for answer that will not rely on Math to prove it... |
I was wondering about how standing waves filter out all other frequencies. I read online that it's because the other frequencies destructively interfere with one another. However as hard as I try, I am unable to picture how they destructively interfere.
Furthermore, if the frequency of the wave was NOT one of the reso... |
I have looked at the Wikipedia article on derivations of the Lorentz transformations, as well as some answers on this site - for example, one on the geometric derivation and another without the usage of sperical wavefronts or hyperbolic functions. But I haven't found what I was looking to clarify - just saying so that ... |
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