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I am studying a one-component reaction–diffusion equation:
$$ \partial_t u(x,t) = D \partial^2_x u(x,t) + R\left(u(x,t)\right)$$
Looking at systems that exhibit a peak solution (solitary localized structures) - are there known general conditions for peak splitting?
|
In many papers, especially these related to the triplet superconductor, the superconductor order parameter, the d-vector, always appears together with the irreducible representation of the space group. Such as the following picture which presents the relation between irreducible representation and the order parameter o... |
I am trying to prove that $$a^\dagger |\alpha\rangle\langle\alpha|=\left(\alpha^*+\frac{\partial}{\partial \alpha}\right)|\alpha\rangle\langle\alpha|.$$
The way I calculate this is, is just by acting with the creation operator on the coherent state.
When I do this I get:
$$e^{-|\alpha|^2/2}\sum_{n=0}^{\infty}\frac{(n+1... |
In Chap. 7.1 of Peskin & Schroeder, the electron mass difference between the physical mass, $m$, and the Lagrangian bare mass, $m_0$ was calculated to be $$m-m_0 = \delta m \rightarrow \frac{3\alpha}{4\pi} \hspace{1mm} m_0\,\log\biggl(\frac{\Lambda^2}{m_0^2}\biggl)\tag{7.29}$$ which diverges when $\Lambda \rightarrow \... |
Two operators, in a suitable basis with matrix representations $A$ and $B$ have the following commutator $[A, B] = AB − BA = kI$, where $k$ is a non-zero complex number and $I$ is the $n × n$ identity matrix, where $n$ can be any integer between 1 to ∞. Determine if the matrices $A$ and $B$ are of finite or infinite d... |
I am studying this paper: Gravitational radiation from a particle infalling radially into a Schwarzschild black hole by Davis et al.
It deals with the calculation of the energy spectrum of the gravitational waves emitted by a point particle falling radially into the black hole. It says that two methods were used for th... |
When we differentiate the total energy with respect to the time and set it to zero (make it stationary), we get an expression as similar to what we get while we minimize action. Also putting the time derivatives of energy equal to 0 means energy is conserved. So, can we say action principle is alternative of energy con... |
Consider the following $SU(N)$-Anderson model,
$$H = \epsilon_{}^{}\sum_{\sigma=1}^{N} c_{\sigma}^{\dagger}c_{\sigma}^{}+\sum_{\sigma=1}^{N}\sum_{k}^{}\epsilon_{k}^{}d_{k\sigma}^{\dagger}d_{k \sigma}^{} + \sum_{\sigma=1}^{N}\sum_{k}^{}\left[g_{k}^{}d_{k\sigma}^{\dagger}c_{\sigma}^{}+g_{k}^{*}c_{\sigma}^{\dagger}d_{k\si... |
Usually, Pauli matrices $\{ \sigma^i \} ~(i = 1, 2, 3)$ are defined as
\begin{align}
\sigma^1=
\begin{pmatrix}
0 & 1 \\
1 & 0
\end{pmatrix},~
\sigma^2=
\begin{pmatrix}
0 & -i \\
i & 0
\end{pmatrix},~
\sigma^3=
\begin{pmatrix}
1 & 0 \\
0 & -1
\end{pmatrix}.
\end{align}
These obey the following well-known algebra:
\begin... |
Let's say I supply heat Q to a system. If it's internal energy increases by U and the work done on it is W then by the first law of thermodynamics, Q = U + W. Now, let's say that due to the thermal expansion, the gravitational potential energy of the system also increases by P. Would it be right to say Q = U + W + P? W... |
This is a bit of a follow up on The Bahtinov focusing mask and it came with this question on Astronomy. But I think the effect can also be observed when looking through a hazy atmosphere or a stained window pane at a distant point light source.
My question is: which physical effect makes a spike move over the light sou... |
It is not possible to simultaneously know the exact position and momentum of a particle as a consequence of non-commutativity of the position and momentum operators. But what if I consider a simple two-particle collision, where I make a simultaneous measurement of the position of one particle and momentum of the other ... |
Let us consider a porous medium and let $\psi$ be a hydraulic head. If $\psi \geq 0$ we say that porous medium is fully saturated, otherwise is unsaturated.
How can I imagine saturated porous medium? I mean, let $\psi = 10$ be a value of fully saturated porous medium (so there can't be more water). If $\psi < 0$ than t... |
The fastest camera available so far is capturing 10 millions images per second.
https://www.shimadzu.fr/hyper-vision-hpv-x2
In the scenario of the currently known physics, but in the hypothesis where technology would allow to have a video camera so fast that it would be able to store images at roughly the frequency of ... |
For elastic collisions, if the mass m1 is much much greater than m2,
the velocity of m1 during the collision remains unchanged while the
velocity of m2 can easily be found by Relative velocity of
separation=(-)velocity of approach.
Heres the problem. Suppose that m1 and m2 are moving toward each other with equal but ... |
I was thinking, what happens to the force on a charged particle when it is moving along the magnetic field lines?
I am familiar with the right-hand-rule and it seems to me that RHR does not apply in this situation. Since the RHR, the field lines, direction of particle moving and the force on the particle are all perpen... |
I was watching the following lectures by Prof. Ashoke Sen. Between 39:00 and 56:00, he was solving the equation of classical field in the AdS global coordinates, and says that the values of $\omega$ are discrete to have regular solutions at $r=0$ and at $r=\infty$. One could write the scalar field equation in Minkowski... |
If it can, how can we write the Hamiltonian of the total System is it just (for example with N bath)
$$
H_{tot} = H_{s} + H_{B_{1}} + H_{B_{2}} + ... + H_{B_{N}} + H_{I_{1}} + H_{I_{2}} + ... +H_{I_{N}}
$$
And can environments be a different structure, for example a qubit modeled by two level system coupled to a bosoni... |
"A charge placed on an insulator is confined to the region in which it was placed. An insulator has no charge carriers that are free to migrate within the boundaries of a body"
(Whelan & Hodgson, Pre-University Physics, 1971, p.268).
If a bunch of negative charge-carriers (electrons) are deposited (e.g. by rubbing with... |
I am studying the paper "Gravitational field of a particle falling in a Scharzschild geometry analyzed in tensor harmonics" by Zerilli. The author calculates the gravitational radiation emitted by a particle falling along a geodesic into a Schwarzschild black hole.
In the appendix I, the author calculates the spectrum ... |
The emf of a cell is defined as the work done per unit positive charge in taking it around the complete circuit of the cell (i.e. in the wire outside the cell and the electrolyte within the cell). But Kirchoff's Second Rule states that the work done in moving a charge around a closed loop is zero. How then do we get a ... |
My textbook states that the observation that a electric current passing through a gas causes characteristic emission spectrum to be observed gives supporting evidence for the wave nature of electrons.
I don't really understand why emission atomic spectra suggest the wave nature of electrons. Doesn't emission spectra gi... |
For a ball of mass $m$, on a string/rope, set in a horizontal circular motion at the top of the circle the ball will make when the velocity is big enough, I understand that the minimum tangential velocity at the top of the circular motion $v$ is given by $$v=\sqrt{gr}$$ since the centripetal force $\geq$ the force of ... |
What is the numerical relation between energy density ( $\Omega_\text{s}, \Omega_\alpha$), and the number density of neutrinos (sterile - $n_s$ , active - $n_\alpha$)?
Background info that might help better understand my question:
This is based on an equation derived through the relationship of sterile neutrinos distr... |
Without recourse to statistical mechanics my book derives the well known Maxwell Boltzmann velocity distribution which is:
$$dN(v)=N\left(\frac{m}{2 \pi k T}\right)^{3 / 2} e^{-m v^{2} / 2 k T} 4 \pi v^{2} d v, $$ but then it simply gives me the formula for the distribution along $x$-axis without proof as$$
d N\left(v_... |
During early classes we are taught that real image of a real object is inverted with respect to the object. Similarly virtual image of a real object is erect with respect to object.
My doubt is that can we make a similar analogy for a virtual image of a virtual object and what would it be?
PS: please do not quote the e... |
Can you shield yourself from Unruh particles? In an old answer to a different question, Ron Maimon says yes:
You should think of the radiation as coming from the horizon--- if you place a refrigerated barrier between you and the horizon, you won't see any radiation past the barrier (at least not until it heats up). Th... |
When studying the general angular momentum $\textbf{J}$, which is defined as a vector operator with its components being Hermitian operators satisfying the commutation relations
\begin{align*}
\textbf{J} \times \textbf{J} = i\hbar \textbf{J} ,
\end{align*}
and the simultaneous eigenvectors of $\textbf{J}^2$ and an abit... |
This question is bothering me ever since I studied Hall effect. Am I probably missing out a point?
To elaborate the question: I understand that Lorentz force and electric force are equal and opposite and therefore the electrons reach equilibrium. But who does the voltage is related to the equilibrium?
Please someone ex... |
Is there any known parallel vector field in a Schwarzschild spacetime? Or any method to identify parallel vector fields in any spacetime, given the metric $g$?
|
I've worked $\rm AdS$ using global coordinates and the ideas of a conformal boundary is plausible. Radial $\rho$ coordinate can be compactified and we can study its conformal boundary at $\frac{\pi}{2}$. However, when we go to the coordinate Patch:
$$ ds^{2} = \frac{1}{z^{2}}(-dt^{2}+dz^{2}+d\vec{x}^{2}) $$
I find ver... |
When you hold a loose string by its two ends, and just let it dangle in space, it looks an awful lot like a parabola. I mean, on first sight, who wouldn't have thought that? It was only upon closer inspection that we realized in fact the shape formed is not a parabola, but a catenary (see the graph of the hyperbolic co... |
Recently I have been looking into different definitions of entropy and came across Boltzmann (unconditional) entropy:
$S=-\int_{R} dx \;p(x) \ln p(x)$
I have tried to calculate entropy of regular Gauss distribution. My logic is that if this definition makes sense, then for nice distributions it should produce reasonabl... |
As we know, the $uds$ transforms in fundamental representations of $SU(3)$. It has the antifundamental partner. According to representation theory,
$$
\mathbf{3} \otimes \mathbf{\bar{3}}= \mathbf{8} \oplus \mathbf{1}
$$
where the $\mathbf{8} $ describes the mesons.
My question is if I am not taking $\mathbf{\bar{3}}$ ... |
Using two different approaches, I appear to receive contradictory information about the tension force in a simple pendulum.
Under the idea of a centripetal force, the Tension - component of $mg$ in that direction(i.e. line of action of tension force) $=$ centripetal force to provide the 'circular motion' for small $\th... |
What is the physical background for the statement that placing polarizers as detectors gives the 'which path information' so the interference pattern disapears? Is it that photons with polarization axes in the same direction can possibly add up or cancel out, whereas two photons with the polarization axes at 90 degrees... |
I'm wondering a bit about the classical Maxwell equations in flat spacetime and their Cauchy problem. For the following, I suppose that the sources are already given and don't react to their own electromagnetic field (this approximation is the simplest case). I consider the following equation to be solved:
$$\partial... |
I am currently playing around with Dirac notation in the context of interband transitions and came across a second derivative of a Ket. Under what conditions will this second derivative be zero: $\langle m | \ddot{n} \rangle = 0$? Or, what other simplifications can I make?
I am used to seeing people drop second-order t... |
I am confused about how to interpret the apparently discontinuity which can arise in the massless limit of dimensionally regulated integrals.
My questions are illustrated by the following example:
Consider the three-point amplitude ${\cal A}_3$ for the Lorentz-violating, effective field theory
$${\cal L}=-\frac{1}{2}(\... |
I am currently looking at Fu and Kane paper: Phys. Rev. B 79, 161408(R).
They write the QSHI edge states as
$H_{\text{edge}}=\psi^{\dagger}(-iv\sigma_{z}\partial_{x})\psi$
where $\psi=(\psi_{\uparrow},\psi_{\downarrow})^{T}$.
upon adding s-wave SC term, they wrote the Bogoliubov de-Gennes Hamiltonian (with $\mu=0$) as
... |
The Lagrangian for a (relativistic) point particle with rest mass $m$ and velocity $v$ is:
$$L=-\frac{m}{\gamma (v)}$$
(using $c=1$). Over on Wikipedia we can find the Stress-energy tensor for said particle; if the four-velocity is $u^\mu=(\gamma (v),\gamma (v)v)$ then the stress-energy is:
$$T^{\mu\nu}=\frac{mu^\mu u^... |
I was trying to learn Quantum physics by myself using MIT's 8.04 course. I came accross this equation:
I don't understand why the above is true. I understand the definition of linearity. But I don't know why two solutions to the above wouldn't be a solution if both sides involve derivatives (I am fully aware that one ... |
Context:
In non-relativistic QM and many-body theory, the second quantization formalism allows us to write a Hamiltonian for a many-body system with up to two-body terms as (up to a re-ordering definition)
$$\hat H = \sum_{ij} t_{ij} a^\dagger_i a_j + h.c. + \sum_{ijkl} V_{ijkl} a^\dagger_i a^\dagger_j a_k a_l $$
where... |
I am teaching myself statistical mechanics using the lecture notes of Professor Leonard Susskind. I am confused about a statement 'reducing $h$ reduces the density' at page $555$. I know the statement is right from intuition since $h$ changes $\bar{\sigma}$. However, I cannot see it from the formulas. And I get more an... |
Consider the question above.
Till now I have interpreted kinetic energy as a consequence of temperature in thermodynamics, i.e., the kinetic energy of a gas is directly proportional to its temperature.
Provided this, in the above question, I have three arguments:
If the gases were to stop, shouldn't the temperature o... |
In the books,it is stated that the energy of a gas system is purely Kinetic for an ideal monoatomic gas.
Why are energies such as nuclear energy not mentioned here?
|
Suppose Alice sends Bob 2 ensembles with 1 billion photons each (or as many photons as you want). In one of the ensembles each of its photons are one of an entangled pair at parallel polarizations while Alice is holding their partners without interaction so they don't decohere.
Is it possible for Bob to create an exper... |
How is matter affected by the warping of space-time? Does it expand and contract, follow the curvature of space? What happens the shape/volume/density of matter when it enters a gravity well, or washed over by gravitational waves?
Note: I dont have a background in physics. Just want a basic layman's explanation, so I c... |
When we calculate fermion determinant for either Majorana or Weyl spinors, why do we get an extra factor of half as the coefficient of the determinant?
|
I need to do an experiment about the launch angle of a ball affecting its splash height. I have no idea if it's feasible or not, and I can't find anything similar online. Can anyone help? My set up is below, please ignore the position of the camera.
|
A theorem in my physics textbook says:
The overall translational motion of a system of particles can be
analyzed using Newton’s laws as if all the mass were concentrated at
the center of mass and the total external force were applied at that
point.
Why does the translatory motion of the center of mass model the motio... |
The fermi paradox asks why we don't see more complex life in the universe if we exist? Essentially, it seems either would naturally develop in our universe, in which case it would be plentiful, or it is a fluke, in which case we probably wouldn't exist. The metaphor I've heard for the latter is that the chance of life ... |
Isn't the pentavalent impurity atom positively charged and attracting the electron?
On receiving the energy why doesn't the electron create a hole in the valence band as it moves to the conduction band? Is it because it is not in a covalent bond? But then also it is leaving a place which can create a hole.
|
I'm not a physicist so probably my question is simple but it's interesting to me to know the answer.
If I have a waterwheel with a controllable gate as in the attached illustration, and I open this gate and the water flows and move the wheel, 1. What's the physical power or character that causes the wheel to move? Is i... |
So the inducing magnetic field points upwards since the field travel south to north in a magnet. The inducing magnetic flux also increases as it heads towards the coil. According to Lenz's Law, the direction of the induced current is such that its magnetic field opposes the change in the magnetic flux that created it.... |
As mentioned in every text book I own, the relative velocities of approach and separation are equal and opposite for (only) 1D collisions. For 2D collisions, only the component of velocities along the line of impact has to be considered. This makes sense since the (impulsive) force, ignoring friction, is always along t... |
I am learning from Jackson (3r edition), where I found one concept very confusing, that is Taylor expansion of charge density. (This is given in section "1.7 Poisson and Laplace equations" p.n:35)
I will write some equations first.
$$ {\Phi}_a(x) = \frac{1}{4{\pi}{\epsilon_0}}\int \frac{{\rho}(x')}{\sqrt{(x - x')^2 + a... |
Say I have a simple free source RC as depicted in the image below. The capacitor initially has a charge of Q on its positive plate and at time t=0 the switch is close. I use the mesh current as shown in the diagram and apply KVL to that loop.
But then the result I get does not have the minus sign infront of the t in t... |
I was studying geometrical optics the other day and my teacher told me about the concept of critical angle and total internal reflection.
He had taken an example in which a beaker was filled with a liquid whose refractive index was $\mu$ and above the beaker after some gap was the eye of an observer in the air (refract... |
I am trying the understand how the weak interaction obeys CPT symmetry. My understanding is that, under a CPT transformation, the Lagrangian for the Standard Model should be invariant, and thus the term that dictates the interaction between quarks and the W boson,
$$L = \frac{g}{2\sqrt{2}}(J^{\mu}W^{+}_{\mu}+ J^{\mu}W^... |
I will briefly summarize what I know and then ask my questions. If you spot mistakes in my summary, please tell me.
The idea of flavor symmetry is that massless QCD is invariant under SU(6) transformations on the 6-dimensional flavor space for quarks. Since up- and down-type quarks are treated different in electroweak ... |
Suppose we had a hollow conducting sphere with a net charge q on it. There is no charge in the cavity; the conductor itself has a charge q. The idea is that this net charge would reside on the 'surface', since the conductor has free charges otherwise to make the net field inside the meat of the conductor zero.
My ques... |
I was reading about the energy stored in an Inductor and first of all I had the question that is this actually stored? The inductor produces a magnetic field which exerts a force on electrons. Isn't the energy spent on this?
While in a capacitor it doesn't exert any force as charges don't flow in between capacitors so ... |
In (Constance Reid 1996, Hilbert, p. 182):
according to Condon: " ... when [Born and Heisenberg and the Gottingen theoretical physicists] first discovered matrix mechanics they were having, of course, the same kind of trouble that everybody else had in trying to solve problems and to manipulate and to really do things... |
So this is from Griffiths particle physics book about pion decaying into neutrino and muon.
The part I have problem with is that it states ``` \begin{equation}
p_{\pi}^2=m_{\pi}^2c^2 , p_{\mu}^2=m_{\mu}^2c^2
\end{equation}
as a true statement for the reaction. I am not sure if p means energy-momentum four vector or j... |
As the title. We can find the approximate solution for large $\kappa$ in any textbook about superconductor.
|
This a school-level based Physics question, but I'm not able to explain myself the answer.
Question : Nickel and Copper wires having same shape, size are connected across a battery in turn. The rate of production of heat will be more in which wire ?
From this table on Wikipedia, I got the following data.
Resistivity ... |
Why is it counter intuitive that for a particle moving in a circle is always being acted upon a force which is directed towards the centre of the circle and not towards the direction of the motion of particle?
|
Given this image:
I just assume that the eye is made out of glass, so I wonder how is it that IR and UV radiation is absorbed by it?
I would understand one of them but why is it transmissible for light between these two regions (visible light)?
Whyever I can't find an absorption spectrum of glass. But I found one of w... |
For a rigid body rotating with a constant angular speed, the points near the axis must have lower linear velocity than the points farther away. If they have different linear velocities, they must have a non-zero relative velocity.
If they have a non-zero relative velocity, the distance between them would change over ti... |
Suppose we have an object thrown up from earth, then, it's energy is given by,
$$ E = \frac{1}{2} mv^2 - V(r)$$
Where V(r) is a potential dependent on distance from centre of earth. By conservation of energy, and some nice assumptions, E is a constant.
Now, suppose we could write velocity as a function of 'r', then, if... |
When we move an electron(e1) towards another electron(e2, not fixed), the work we do is stored as potential energy in e1 but from where does e2 get energy to be repelled? What is source of potential energy in e2?
|
Suppose a Hamiltonian H is time reversal symmetric: $ΘHΘ^{-1}=H$. And H can be decomposed under a complete basis $|k,α⟩$, i.e. $H=∑_k∑_{α,β}|k,α⟩⟨k,β|$, and I am trying to deduce the corresponding form for the time reversal symmetry of $H(k)=∑_{α,β}|k,α⟩⟨k,β|$. The answer should be $θ·H(k)·θ^{-1}=H(-k)$. Yeah, this is ... |
Q: An amusement park proprietor wishes to design a rollercoaster with a vertical circular loop in the track, of radius $R = 20\, \rm m$. Before the cars reach the loop, they descend from a maximum height h, at which they have zero velocity. Assuming the cars roll freely (no motor and no friction), how large must h be ... |
For example, sound interference could lead to a loud room feeling louder simply because of sound waves colliding. Or an orchestra which is perfectly synchronized could create loud and quiet spots in the concert hall. Are there any everyday situations where some kind of sound waves interference could be demonstrated?
|
Newton's second law, $\vec{F}=m\vec{a}$, is form-invariant only under Galilean transformations but not under Lorentz transformations. Then why do we say that Newton's law is valid and form-invariant in any inertial frame?
Is the definition of inertial frame different in Newtonian physics and Special relativity? So th... |
The Rutherford Model of the atom was similar to the solar system. The major drawback of the model was that it was not consistent with maxwell's theory of electromagnetism which stated that :
All charged accelerated particles emit electromagnetic radiation.
The electrons were charged and were accelerated due to their ci... |
I want to know whether Purity is monotonically decreasing for increasing Von Neumann entropy or not.
In other words, I want to know whether the following proposition holds or not,
\begin{align}
S(\rho_1)<S(\rho_2)~~~~\Longleftrightarrow ~~~~
\text{Tr}\rho_1^2>\text{Tr}\rho_2^2,
\end{align}
where $S(\rho)=-\text{Tr}\rho... |
Is there any difference between electron and muon in spin change behaviour(like with mass)?
In Muonic hydrogen the "21cm line" will have different frequency, but not of the spin difference, but again of mass, eh?
I mean that is no matter what fermionic particle sits in the Ising lattice, no difference...
or interaction... |
In hydroelectric power generation, I've got a pretty good understanding for how kinetic energy from falling water is transformed into electrical energy. But when looking at the entire system, what thing is losing energy such that work can be done by the electricity that is generated?
For example, when electricity is ge... |
Consider the above scenario: In the subsequent motion, we need to find the work done by tension on the (trolley + mass) system.
Solution: Suppose at an instant, the velocity of the trolley (and hence that of point $A$) is $\vec{V_{a}}$, and the velocity of the point mass is $\vec{V_{b}}$. Then the power delivered by t... |
In all the books, that I have studied so far, they say that Carnot cycle is the most efficient cycle. But why isn't any other reversible process as efficient as Carnot cycle? Can somebody please provide mathematical explanation for why that is or isn't the case?
|
I wanna consider some cases and make sure if im right ,
if i have fixed volume balloon filled with helium , and let balloon fly in air ,
1)
if air temperature increases , ( without increasing temp of helium ) that will decrease density of air , so buoyancy force decreases.
2)
but if helium temperature increase , volume... |
On the Wikipedia page for the Twin Paradox, the example lays out the perspective of each twin in turn. Both twins are portrayed as understanding the ship's velocity as v, and the travelling twin's sense of time is then explained by saying that the earth-distant star system, being in effect one giant object, undergoes l... |
Context: I've been reading about The Hairy Ball Theorem which shows that the ideal shape for magnetic confinement fusion has to be a torus. Given that tokamaks use toroidal magnetic fields, I assumed that plasma leakage then wouldn't be a problem.
What is the cause of plasma leakage?
(If I misunderstood anything, feel ... |
I do not understand what the first and the second fluctuation- dissipation theorems physically represent and what are the differences between the first and the second on the physical side. As a reference, I am reading Sauermann et al. "The quantum statistics of dynamic processes", but I think I need a key to interpreta... |
The question is as title in the context of condensed matter physics. By Dirac cone I mean the bands in momentum space touch at some k-point and thus forming Dirac cones. This gives rise to low-energy effective massless theory: Dirac theory. However, different from high-energy massless theory: QED, I don't see an analog... |
If heat is random molecular motion, does perfectly laminar flow register a temperature?
|
How are the correlations in the experiment proposed by John Bell explained by many-worlds theory?
I understand that the assumption of a measurement having a single outcome, is not supported by many-worlds. And hence it may violate Bell's inequality.
But it still has to explain why correlations occur when the experiment... |
I wanna ask why were the mass of first quarks not something like a very large number (because a lot of energy was present in that expanding universe) or much more than what we know from calculations ?
In my previous question (How were quarks made?) I came to know that quarks formation is explained by Higgs mechanism bu... |
Consider a 2*2 block toeplitz real matrix A . The (i,j) block is given by
$$ \begin{matrix}
-f_{i-j} & g_{i-j} \\
-g_{j-i} & f_{i-j}
\end{matrix}
$$
where i,j go from 1 to L.
f satisfies $f_{-a}=f_a$. Let $\vec{V}$ be an eigenvector of A, with eigenvalue $i\lambda$. (The eigenvalues have to be imaginary because A is a... |
Let's keep things simple and assume that the wheel does not slide. Assume you are in a car that moves with constant speed. Obviously, the wheels exert a tangential force to the surface on the road in the points of contact, P. According to Newton's third law action equals minus reaction so the road exerts a force to the... |
Suppose you have an ice cube in a nonflowing liquid bath of m, where m is an element with a freezing temperature far below water (and whose temperature for this thought experiment is far below water’s freezing point).
Will the ice cube get colder if it is placed in a flowing bath of m? That is, will the direction of he... |
An Ideal gas is taken through the cycle $A \rightarrow B \rightarrow C \rightarrow A$ as shown in the figure. If the net heat supplied to gas is 15J, the work done by gas in process C->A is..?
So, I did this problem in two methods and each one gives me a different answer.
Method 1.
Notice, $C\rightarrow A$ forms a s... |
I am interested to know if there are any general techniques for diagonalizing the operator of the form
$$\left({\rm i}\partial_t- \frac{1}{2}t^{3/2}\mathbf{A}\partial_p+ t^{-3/2}p\mathbf{B} \right)$$
where $\mathbf{A}$ is an $n\times n$ diagonal matrix of constants, and $\mathbf{B}$ is an antisymmetric matrix of consta... |
If you plot a space-time diagram of an object falling through the event horizon of a black hole, and draw the past and future "light cones" of the object at every point, wouldn't the point infinitely to the event horizon have a light cone which allows light being radiated by the object to reach an observer outside the ... |
I'm currently going a little more in depth with thermodynamics and I'm trying to familiarise myself with Mollier's diagram. What I don't understand is how to read precise values given the initial conditions. For example, I am given $p=0.6MPa, T=473,15K$ and I want precise values for enthalpy, entropy and specific volum... |
An observer at rest or in motion different from the particle cannot determine its momentum and position to great accuracy at the same time. But what if the observer is on the particle itself or moving with the same velocity as the particle?
|
When studying an introductory course on particle physics, I came across the following question:
What is the action describing electromagnetic fields coupled to charged fermions?
I have already seen the Dirac Lagrangian but I cannot seem to find a way of coupling electromagnetic fields to charged fermions with it. Any ... |
updated 8/27/2020
While the recession of our Moon from the Earth may slow and even stop,
(see When will the Moon reach escape velocity?)
binary star systems will
(1) never stop experiencing mutual tidal forces,
(2) continuously experience loss of mass and gravitational attraction,
(3) lose energy by gravitational wave ... |
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