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Before now, I had never questioned this matter. Why must we assume a probability density distribution (pdd) as opposed to a general density distribution (gdd)? Perhaps I have a misunderstanding.
My current understanding is that a pdd for an electron would suggest that the electron is never in one place, but given a coo... |
So, I had come to the agreement that to understand how antennas work, it is best to assume light/electromagnetic waves act like photons/particles in the presence of recieving antennas. And therefore a high frequency waves consume more energy and less in intensity, but more in energy(As in each photon has more punch on ... |
Here we need to keep terms originating from the same line.
|
The problem is as follows:
Two homogeneous spheres are at equilibrium by the action of an
horizontal force of minimal magnitude $F= 25\,N$, as shown in the
picture from below. The sphere which is in the bottom has a weight of
$10\sqrt{3}$ and the upper sphere has a weight of $25\sqrt{3}$. Using
this information, find ... |
According to quantam mechanical effect an unpaired electron in one atom interacts strongly with the unpaired electron in the neighbouring atom in such a way that they align them self in a common direction over a small volume of a material called domain.
In the absence of the direction magnetic movement in different dom... |
Sorry of this question is super general, but how would you convert between a 3D pressure limit in $N/m^2$ to a 2D pressure limit in $N/m$ if the boundary is arbitrarily thin?
I've heard before that you multiply the pressure limit by the "width" of the boundary, but what about in this case? Thank you!
|
I am not sure the validity of this claim from Wikipedia on 't Hooft–Polyakov_monopole
The "monopole problem" refers to the cosmological implications of grand unification theories (GUT). Since monopoles are generically produced in GUT during the cooling of the universe, and since they are expected to be quite massive, ... |
I know from ${\bf F}=q({\bf v}\times {\bf B})$ the force is perpendicular to displacement and so work by magnetic field is always zero. But then how is that a magnet is able to displace any magnetic or metallic object and still cause no work because the motion of the object should be in the direction of force. So what ... |
What is the cause of the reduction in peak microscopic cross section with increasing temperature, shown here for a nuclear resonance?
The nuclear properties of the target material do not actually change with motion, so why does the peak reduction of the target's microscopic cross section ("effective area") suggest tha... |
Summary: Brillouin states that an inhomogeneous hyperbolic PDE has a finite solution only if the RHS is orthogonal to the homogenous solutions
Hi, I've been reading Brillouin's 'Wave Propagation in Periodic Structures'.
About the following equation
$$\nabla^2u_1+\frac{\omega^2_0}{V_0^2}u_1 = R(r)$$
Brillouin states th... |
Prony method is a method for calculating the quasi normal mode from time domain data. It is bades in the solution of a linear system as described in this paper. What I do not understand is how many damped exponenets of the form:
$$\Phi(t)=\sum_{j=1}^pC_j \, \exp(-i \omega_j t)$$
should be present in the summation, from... |
The answer seems obvious, it's our energy that gets converted into kinetic energy. But my question is how exactly? Which force is responsible for doing work on us so that we gain kinetic energy? It can't be friction as the point of contact with the ground is at rest. Is it some kind of internal force that does this wor... |
I can hardly find any information.. and the few I got from my script is not revealing so much:
Electrons are strongly bounded (ceramics) – electrons are transported from a bound state into an energetically similar vicinal state by thermal activation (hole transport).
Is it just that? For me, this could also be appl... |
I was going through a conference presentation on System of Systems Engineering. In the presentation entitled "Macroscopic Quantum Mechanics and the SoSE Design Approach", I came across a slide distinguishing classical observation as a phenomenal and quantum observation as phenomenological.
This is the slide which i am ... |
Actually I have studied that the smaller the mass of a particle, the fastest it can travel in space. (But i don't know the mass of a single proton) and my question is: can any particle travel faster than a single photon?
|
My physics professor recently covered the concept of simple harmonic motion and touched on vertical springs. However he mentioned that the spring (with a mass attached to its end) only undergoes simple harmonic motion if it is massless. However I am unsure why making the spring have non-negligible mass would affect its... |
I wish to build a Fusor. Now, in order to build it, a high voltage is required generally achieved through Neon Sign Transformers. If I want to achieve voltages 25 kV or more, how am I supposed to do it? I could possibly use a voltage multiplier but I am not sure if it is a great idea. A voltage multiplier can not provi... |
Imagine two hydrogen atoms which are close together, but not yet bonded. According to molecular orbital theory, the wavefunctions of their 1s electrons have to be in phase for them to interfere constructively and create a bonding orbital that is lower in energy. Does that mean than even if their phases are opposite to ... |
Let's say we solve the Schrodinger equation with infinite well. We can quantize the field by the resonance state and can get the annihilation and creation operator. So we will get the sort of particle corresponding to the resonance state. The resonance state would have mass corresponding to the energy and the mass will... |
How can I observe quantum effects of any corpuscle - photon or electron, or even atom.
Is there civil-grade not much expensive electron microscopes or any other ways?
I understand, that I can not build even small collider, because it is very expensive.
Is there any bypassing to observe ONE photon as corpuscle or electr... |
How to determine the current expansion rate of the universe from observing past objects?
When we look into the light from objects far away, it not only very very far away in the distance it is also very further away in the past. So does this help us find the current of expansion?
|
We are clearing out some old cupboards at school in our science department and have come across three different sets of physics equipment with no labels or instructions. Please could people kindly identify these if possible and what they would be used for in terms of a practical and if it is therefore worth keeping the... |
Consider the case here,
A uniform rod of mass $m$ and length $l$ is hanging vertically from the pivot $O$. A horizontal force $F$ acts at the lower end of the rod. If $F$ always remains horizontal then what is the maximum angular displacement of the rod? The image below show the rod's initial and final state
The rod ... |
I am studying Adel Belali's review paper "M(atrix) theory: a pedagogical introduction" for my undergraduate thesis. In the third lecture, part one, we dimensionally reduce 11D supergravity to get type IIA SUGRA and retain the 128 bosonic degrees of freedom and 128 fermionic degrees from the original theory. I have gon... |
Do I have to compute the area moment of inertia along the principal axis of the cross-section, in order to find the maximum beam deflection of a cantilever beam with a random polygonal cross-section?
As far as I know, to compute the maximum beam deflection of a cantilever beam with a polygonal cross-section under a poi... |
We derived $dU = nC_vdT$ taking $dV = 0$. But we found that this is true not only for $dV=0$, but for all cases.
Similarly, we derived $dQ = nC_pdT$ taking $dp = 0$. So, can we say that this is true for all cases as well?
|
Let's assume a mass that is hanging somewhere. My question is basically:
We are applying a force from the side to move the mass sidewards
We are applying a force from below to move the mass upwards
Are these forces the same?
In this context, a bit more concise and realistic:
A box, weighing 100 kg, is hanging from a ... |
My book Halliday et al. gives a proof of the path independence (conservative force). It is said that the net work to move a particle from a to b and then from b to a is zero. Thus the work done from a to b equals minus the work done from b to a.
The book states that minus the work done from b to a equals the work done ... |
Lots of textbooks quote the formula $\mathcal{E} = \oint(\textbf{v}\times\textbf{B})\cdot{\rm d}\textbf{l}$ for the EMF induced along a circuit moving at velocity $\textbf{v}$ inside a stationary magnetic field $\textbf{B}$.
But then, what if instead the circuit was stationary, and the field was moving with velocity $\... |
Generally in text books they say that when a electron goes from high energy state to a lower energy state it emits photons.
My question is, it is possible that a proton that goes from high energy state to a lower energy state emits photons too?
|
So I understand that similar questions has been asked before. There is a specific aspect I don't understand which I don't think has been explained.
If I shine a light on a surface and then I add a barrier, isn't there still a some photons remaining on the other side of the barrier which will still be travelling toward ... |
Gauss's Law for magnetism is
$$
\nabla \cdot B = 0
$$
This allows us to write the magentic field $B$ as the curl of another field the $\textbf{magnetic vector potential, } A$.
$$
B=\nabla \times A
$$
This adhers to $ \nabla \cdot (\nabla \times A)=0$
However, if a monopole does exist then we have
$$
\nabla \cdot B= \rh... |
When I look at the velocities of elliptical orbiting satellites the radial velocity (k in the figures) increases from zero magnitude at periapsis, to a maximum at the latus rectum, then back down to zero at the apoapsis. This describes a rate of increase opposite the direction of gravity that changes over time.
From pe... |
Recently i was reading about neutron absorption by metals. But there are always two different categorizes for thermal neutrons and fast neutrons. I don't understand what difference between them!
Most importantly i want know fast neutrons or thermal neutrons are used for adding neutrons into atomic nuclei (increase neut... |
Problem: A small marble of mass m and radius r rolls without slipping along the loop-the-loop track (pic attached). If it starts from rest at a height of 6R above the bottom (R =radius of the circular part of the track), what is the force (horizontal and vertical components) acting on it at the point Q.
I was able to f... |
If there is a block on a ramp, and it slides to the bottom (with friction), then is the work done by gravity always equal to the work done against friction?
|
I understand that there is difference between thermal and fast neutrons according to their energy. Now, if one wishes to add neutrons into atomic nuclei, it should be easy as neutrons are neutral, so they can pass by the electron clouds and they don't get repulsed by nuclei itself, so no high energies are needed. Moreo... |
The presence of the unmodified line (wavelength) in the scattered X-ray beam, in a Compton scattering experiment, is called the Rayleigh line. This line originates from the Compton scattering of the X-ray photons with the electrons so tightly bound that the entire atom recoils. Hence, the Compton shift is negligible. ... |
I have searched everywhere I know to look but I cannot find out how Hamilton's equations deal with non-conservative forces. In my understanding, Lagrangian mechanics deals with this as follows: the Euler-Lagrange equations no longer have a zero on the right, they have a term $$\Sigma F_q$$ that is the sum of all the no... |
If you take Einsteins field equation with a homogenous (and isotropic) mass density, no pressure, no cosmological constant and a flat, non-expanding spacetime, the result is a collapsing space-time (right?).
If you consider a system of two (relative to each other) still-standing bodies with no non-gravitational forces ... |
Apparently, if a bar magnet held in a horizontal plane on earth is rotated by any angle $\theta$, the null points of the magnetic field rotate by $\frac{\theta}{2}$.
My professor just explained this using an example of rotating it by 180° from a position parallel to the magnetic field lines of the earth.
Can somebody p... |
We know that heat capacity is an extensive quantity, basically meaning for double the amount of substance you need double the energy to increase temperature. To what extend is this actually true, like:
Are there e.g. (measurable) surface effects?
Have (precision) experiments been done on this?
|
I was looking in ENDF for neutron cross section (barn)/neutron energy plots in different elements. As i looked throw many elements, i realized that there is always an area at specific energies where the graph become "abnormal", i gave 9 examples in the figure below (i circled the "abnormal" area with red).
Does anyone ... |
I am trying to solve the very first problem from the book "Physical Paradoxes and Sophism"
The problem is as under:
1.1. The Amazing Adventure of a Subway Passenger:
Every morning a muscovite goes to work by a subway train. Although he starts work at the same time every day, he arrives at the subway station at variou... |
I am doing a Master in Physics. My area of research is experimental particle physics. During the literature review, I have read this statement many times, this happens because of the Cronin effect, then I started to understand what is Cronin effect, but unfortunately did not found any source. Please explain clearly and... |
I think that the following statement is true, but can't seem to prove it.
Suppose we have a scalar field whose Lagrangian density$^1$ $\mathcal L(\phi, ~\partial_\mu\phi, ~X^\mu)$ is Lorentz invariant. By this I mean that $\mathcal L(\phi, ~\partial_\mu\phi, ~X^\mu)=\mathcal L(\phi, ~\Lambda_\mu^{\;\;\nu}~\partial_\nu\... |
I read about Electron Capture or K-Capture in radioactivity. There I found that the electron in the K shell is captured by the nucleus and as a result the atomic number of the element decreases by 1 unit.
But by Heisenberg's-Uncertainty-principle states that electron cannot fall into the nucleus because it's speed will... |
I am still rather new to renormalising QFT, still using the cut-off scheme with counterterms, and have only looked at the $φ^4$ model to one loop order (in 4D). In that case, I can renormalise with a counterterm to the one-loop four-point 1PI diagram at a certain energy scale. I can choose an on-shell point $\{s={ \sig... |
In the realm of injection of electrons into a solid what are the difference between hot, ballistic and thermal electrons?
Is the injected electron ballistic electron? Are they mutually exclusive terms? When does a ballistic electron become a hot electron? When is proper to use which terminology?
|
The Lagrangian for ED without Gauge fixing term is given by
$$\mathcal{L}=-\frac{1}{4}F^{\mu\nu}F_{\mu\nu},\quad \text{where}\quad F_{\mu\nu}:=\partial_\mu A_\nu-\partial_\nu A_\mu.$$
I was wondering if this step, defining $F_{\mu\nu}$ over the $4$-potential $A_\mu$, is necessary. Can't we just formulate electrodynamic... |
A test charge $q$ is placed in front of a non-conducting sphere of charge $Q$ at a distance $r$ from the centre of the sphere. We consider the sphere as a 3d-symmetrical body, we write the electric force on a test charge $$F = \frac{Qq}{4πε_0x^2}$$ where $ε_0$ is the permittivity of air.
But in the sphere there are ma... |
https://en.wikipedia.org/wiki/Force_between_magnets
In this article, for the ampere model section, wiki talks about how we can think of permeant magnets as having current flowing through them and it is this current which causes magnetic field. Now, my question is how is there current flowing through a magnet? does this... |
My idea is to make a new form of enriched uranium fuel (or more accurately, a substitute for enriched uranium) that's made by mixing uranium-233 (transmuted from thorium in a breeder reactor) with a larger quantity of natural uranium. The uranium-233 is a substitute for the additional uranium-235 in traditional enriche... |
I am learning quantum physics, and came across $n$-dimensional Hilbert spaces, is there any way one can visualize a $n$-dimensional space and the n components of the vectors existing in that space?
P.S. I am currently in 10th grade and don't know who to ask. It will be really amazing if someone could help.
|
In Zangwill's second chapter (on Maxwell's equations), problem 2.4 states the following-
"The magnetostatic equation $\nabla \times \textbf{B} = \mu_0\textbf{j}$ is not consistent with conservation of charge for a general time-dependent charge density".
Can someone explain why this statement is valid?
|
This is a copy of the question on the electronics stack exchange site:
I don't have much of a EM background but I have used stepper motors for things. What's not clear to me is why don't stepper motors ring indefinitely?
Excluding physical friction, what actually causes a stepper motor to stop at a given location? It's... |
Working through chapters 6 through 8 in Srednicki's "quantum field theory", I am having some trouble conceptually understanding what is happening when we take time ordered products of operators in expectation values.
For example, when considering the path integral of a free field theory what I picture the functional in... |
I got this question in school:
Explain, based on the properties of an ideal gas, why the ideal gas law only gives good results for hydrogen.
We know that the ideal gas law is $$P\cdot V=n\cdot R\cdot T$$ with $P$ being the pressure, $V$ the volume, $n$ the amount of substance, $R$ the gas constant and $T$ the tempera... |
For a two-dimensional cartesian coordinate system $(x,y)$ describing two particles of unit mass, one frequently encounters a transformation into center-of-mass and relative coordinates $(R,r)$ defined by
$$
\begin{pmatrix}R\\r\end{pmatrix} = \begin{pmatrix}1&1\\1&-1\end{pmatrix} \begin{pmatrix}x\\y\end{pmatrix}
$$
How ... |
In a complete orthonormal basis $|x\rangle$, we often use the completeness relation:
$$\sum_{n=0}^\infty | x \rangle \langle x | = \mathbb{I}$$
if the basis is continuous we use the natural extension
$$\int | x \rangle \langle x | dx = \mathbb{I}.$$
This makes sense only if the choice of basis is complete. What if it i... |
2 different planets far away from each other, each have an extremely strong water canon. Those 2 canons are aimed to the sky, aimed at each other. They both shoot a massive load of water to each other, targeting each other. The water moves like 2 spheres of water towards each other at a constant speed. Independently th... |
A quantum particle that has no spin, no charge, no interaction can be 'modelled' by $\phi(x^{\mu})$. This is a particle that moves freely; random one could say as well.
In classical mechanics if we have a field, we can find the particle in a certain point in spacetime. In quantum mechanics, we can only find the probabi... |
Take a ferromagnetic material which has been exposed to an external magnetic field $h_0$ for a long time and therefore has and equilibrium magnetization $m_0$. The external magnetic field then flips to $h_1$, where $h_1=-h_0$. Over some period of time, the material's magnetization will reach equilibrium at $m_1$. How l... |
So I was just reading a bit about magnetic dipole moments, Larmor precession, angular momentum etc., but there was one little thing that was bothering me. As far as I know, any angular momentum will precess around any magnetic field, no matter how big the angular momentum and the magnetic field is. So the angular momen... |
The lorentz transformation matrix (for all 3 spatial axes, not just a single dimension boost) appears to be commonly defined as the following:
$$
\begin{bmatrix}
\gamma &-\gamma v_x/c &-\gamma v_y/c &-\gamma v_z/c \\
-\gamma v_x/c&1+(\gamma-1)\dfrac{v_x^2} ... |
Say we have a putative 4d gauge theory coupled to fermions of various representations. In order for this theory to be consistent, we need to check that no there are both no triangle anomalies and no Witten anomaly. Is this a complete list of the anomalies we need to worry about? If so, how do we show this?
|
I have recently been reading literature on geometric constructions of representations of affine Lie algebras by Nakajima and others. In particular, the representations arise as cohomologies of moduli spaces of sheaves on a surface.
For a smooth surface, $S$, if we consider the Hilbert scheme of $n$-points $S^{[n]}$, fo... |
I am reading that the electromagnetic force is only transmitted when 2 objects with charge move relative to each other.
In that case, would 2 electrons that are not moving repel? Would 2 unmoving protons attract?
How does static electricity work in if motion is required?
|
How the photon doesn't carry a charge yet there is an electromagnetic interactions with (I mean using)that photon, right?
Modification:
In other-words, how a non-charged particles interact with charged particles?
|
I am following Sidney Coleman's lectures of Quantum field theory, where in ch 24 (page 509) he wrote down the non-derivative pseudoscalar type interaction Lagrangian between the proton $p$ and neutron $n$ mediated by neutral pion $\pi^{0}$ and charged pions $\pi^{+} \& \pi^{-}$:
$\mathcal{L} = g_{P} \bar{p} i\gamma_{5}... |
Is it true or wrong that the interaction between the system to be measured and the measurement apparatus is always electromagnetic - even when looking at gravity or at nuclear interactions?
Is it true or wrong that the bath in the (classical) measurement apparatus is always coupled to the outside world via electromag... |
I have to calculate the capacitance of a spherical or a cylindrical capacitor (The problem contradicts itself) and the free charge density at any point of the inner conductor. The region between the conductors is filled with four diferent dielectrics. As it can see in the image:
The system has a potential difference $... |
We've seen it in a million stories--starships get destroyed in battle. What happens afterwards, though?
How far can that debris go before it's eroded to harmless atoms? There was a question about an object going 99.99% of lightspeed over on Worldbuilding which showed the object would be quickly vaporized in interplan... |
I always found Legendre transformation kind of mysterious. Given a Lagrangian $L(q,\dot{q},t)$, we can define a new function, the Hamiltonian, $$H(q,p,t)=p\dot{q}(p)-L(q,\dot{q}(q,p,t),t)$$ where $p=\frac{\partial L}{\partial \dot{q}}$. Here, we are also expressing $\dot{q}$ as a function of $(q,p,t)$ by inverting $p=\... |
Consider the following experimental setup:
2 parallel lines close to each other. The direction of +ve x-axis is same for both the lines.
There is a standard 1-meter rod on each of these lines. Let they be called S and S'. The end-point towards the +ve x-axis for S is P and S' is P'. The other end-point is O and O' res... |
If I had a 10km vertical tube of water, would the water at the bottom be quite hot?
The reasoning I have is that, as $p=\rho gh$ then as the depth increases, then so should the pressure. However, pressure in a fluid is caused by nothing other than the collision of water molecules against other things. If the pressure i... |
The mesh on a microwave is conducting and therefore acts as a Faraday cage if the mesh's holes are smaller than the wavelength of microwaves. My question is whether a similar effect can be achieved for sound. Say, I construct a cage similar to the one shown in the image, with sound absorbing walls and a mesh at the ope... |
According to my textbook when no electric field is applied,
The elecrons in the solid conductor will be moving due to thermal motion during which they collide with the fixed ions. An electron colliding with an ion emerges with the same speed as before collision.
In the end, they conclude that since there is no prefer... |
The sweat on our body evaporate taking energy from our body in the form of heat.the temperature of our body decreases and we feel cool. Thus sweating cools down our body.
Now why does our body cool down faster?
All the sources I have come across to find the answer,as I understan , state that,
the fan speeds up the evep... |
Newton's second law for a nonrelativistic particle of mass $m$ in 1D, reads, $$F \bigg(x, \frac{\mathrm{d}x}{\mathrm{d} t}, t \bigg)=m \frac{\mathrm{d}^2 x}{\mathrm{d} t^2}$$, where $F$ is the net force function. Now, if we assume that $F$ is time-independent and that $v=\frac{\mathrm{d} x}{\mathrm{d} t}$, can be writt... |
I have been wondering to find the answer of some fundamental questions in quantum mechanics and the answer to the above question will help me to clear doubts of quantum world
|
I came across the following question:
Three segments cut from a long elastic light cord are knotted at point $P$. The other ends of the cords are attached to the ceiling so that all the segments are in a vertical plane and the angle between outer and middle segments each being $ \theta $. A load of mass $m$ is suspende... |
I have studied several resources about the band structure of graphene. They always mention that the Dirac point in graphene is protected by time reversal symmetry and inversion symmetry. I can understand that inversion symmetry corresponds to the same on-site energy (in other words, it has the same element in the 2x2 H... |
This relates to humans carrying or throwing rocks, so it relates both to mechanics and biophysics.
Let's say you stand at point A where there is a pile of rocks. You need to get the rocks to point B. You can choose between 1) carrying them or 2) throwing all of them as far as you can, and then walking to the new pile a... |
I've been reading the Wikipedia article on phonon. So, my understanding is what they get is the discrete energy levels of vibration from quantization. But the discrete energy level is not only the property of the quantum system but also the property of classical harmonic oscillator.
And if they can describe the vibrati... |
I was recently studying centre of mass of a body and while studying the motion of the centre of mass it was stated that if no external forces act on a system the centre of mass remains stationary as the internal forces get cancelled out. Is there any situation in which the internal forces do not cancel each other out?
|
The numerical is given below:
Q: Compute the magnetic field of a long straight wire that has a circular loop with a radius of 0.05m. 2amp is the reading of the current flowing through this closed loop.
My teacher solved the above numerical as follows:
But I have a question that is:
Q: In ampere's law, there is a dot ... |
A tree root lying under several square meters of 100mm thick concrete pavement can cause the pavement to lift up as it grows.
What forces are involved in creating this lift?
I vaguely understand that the growth process is a matter of cell division, but my layman brain can't reconcile this with lifting so much weight.
I... |
I'm unable to understand how friction causes motion in cars and also is responsible for stopping them.
When it starts the impending motion of tyres is in the backward direction that's why friction is in the forward direction and the car starts moving.
But when the car engine turns off, the car stops after some time, bu... |
I have been searching for an audible track of stellar oscillations inside a pulsar, but I don't seem to find what I want. No, I am not asking about the radio waves emitted that have been converted into audible sound. I'm asking about the trapped sound inside a pulsar. My questions relates to Asteroseismology, if that c... |
In short: A laser at frequency $\omega$ gets phase-modulated at $\Omega$ (e.g. with an electro-optical modulator), such that the lowest order sidebands appear at $\omega\pm\Omega$. If this laser beam is detected with a photodiode (with sufficient bandwidth), will there be any measurable beat notes, e.g. at $\Omega$ or ... |
Suppose I have some simple isolated system, so the entropy is given (according to the Wikipedia page on Hemholtz free energy) by
$$ S = k\log Z +\frac{U}{T}+c$$
where $Z$ is the partition function, $U$ is average internal energy, $T$ is temperature, and $c$ is a constant. Some process adds a bit of heat to this system.... |
When trying to convert a continuous variable (running time of a piece of code) into a quantised one (s on a clock), I've been trying to work out the effect of instrument resolution on the uncertainty of my measurement.
What I'm trying to do is measure how long a task takes using a timer with resolution $r$, and then co... |
Friedman and Susskind in their Special Relativity and Classical Field Theory use the following Lagrangian for a charged particle in electromagnetic field characterized by the 4-vector potential $A_\mu$.
$$
L = -m\sqrt{1-{\dot{X}^i}^2} + e\dot{X}^\mu A_\mu
$$
From this, doesn't it follow that the dimensions of $A_\mu$ a... |
By demanding the the Dirac equation be invariant under general Lorentz transformations, we get an equation for the transformation matrix of a Dirac spinor,
$$ S^{-1}(\Lambda) \gamma^\mu S(\Lambda) = {\Lambda^\mu}_\nu \gamma^\nu, $$
such that the spinor transforms as
$$ \psi \quad\stackrel{{\Lambda^\mu}_\nu}\to\quad S(\... |
The probability of a particle going into either of two slits is given, classically, by
$$
P=P(\text{slit}_1)+P(\text{slit}_2)=|\psi_1|^2+|\psi_2|^2=1 \tag{1}
$$
This probability must be equal to $1$ as the probability of going through either of two slits is 1.
Likewise, in the quantum scenario, the rules for probabilit... |
Do neutron stars produce sound?
In the answer to the above question, it has been mentioned that:
'The pulsar signal is often transformed directly into an audible signal by simply feeding it to a loudspeaker.' But as far as I know, the sound that we hear from the pulsars are radio waves that have been converted into aud... |
The Meissner effect expels magnetic field lines in a super conductor, see the picture below. Left is normal conducting, right is the superconducting state.
If I have a superconducting wire of radius $r_0$ now, the Meissner effect leads to $B(r<r_0)=0$. When I drive a current $J(r<r_0)=J_0$ this current leads to zero f... |
In this paper here
It defines some time scales.in page 3 was said that
$$
\tau_E^{-1}\equiv min |\epsilon_{mn}(t)| \quad ,m \neq n
$$
where $ \epsilon_{mn}(t) ≡ \epsilon_m(t) − \epsilon_n(t)$ denotes the instantaneous
energy gap. Hence, $\tau_E(t)$ also corresponds to the longest
timescale of the intrinsic oscillation ... |
Today I was reading about mass-energy equivalence and their respective conservations laws. I have come up with two definitions about mass:
Amount of matter an object consists of.
A measure of an object's inertia.
I was always satisfied with the first definition. That is, mass is about how many particles an object ha... |
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