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In the RNS formulation of superstring theory we have the action:
$$S=-\frac{T}{2}\int d^2\sigma(\partial_\alpha X^\mu \partial^\alpha X_\mu + \bar{\psi}^\mu \rho^\alpha \partial_\alpha \psi_\mu)$$
where $X^\mu$ is a worldsheet scalar and $\psi^\mu$ is a worldsheet spinor. We can Fourier decompose these two. For the ope... |
Consider a rotating disk and a fixed part that "abrades" something. Under normal conditions the disk and the fixed part should not touch. However, they slightly touch due to misalignment. When the disk rotates, this results in friction which ultimately causes heat.
Very intuitively, the higher the angular velocity, the... |
Suppose I have a gas at equilibrium in a box weakly interacting with the room (weak exchange of energy but absolutely no exchange of particles, so that we are in a canonical ensamble). The gas interacts with the room. Does this count as a measurement? In what eigenstate does the gas collapse to then? The room has the s... |
I saw Liquid-Mirror Telescopes. With care, a liquid mirror can make a diffraction limited telescope.
The Wikipedia article on Liquid mirror space telescopes talks about various designs for use in space, including one where the liquid is frozen. This article is a stub with little detail.
Long ago, I read where a large... |
I have a conceptual question, suppose we have a floating object (like a satellite), inside it we generate a beam of electrons that impact a positively charged metal plate, which produces an attractive force, this internal force will move the floating object?
I was convinced that it was, but they told me that the net fo... |
I've often seen the identity
\begin{equation}
k^\mu k^\nu = \frac{1}{4}k^2\delta^{\mu\nu} \tag{1}
\end{equation}
used in various derivations (for example, see Schwartz QFT pg. 625). This result doesn't make any sense to me. Let's consider the simple four-vector
$$
k^\mu = (1,0,0,0)
$$
Here, $k^2 = 1$ (using mostly-minu... |
I've been reading an article and it gives me the following formula:
$\vec{v}_B(t) = \vec{v}_0 - \mu_sgt \hat u_0$
It governs the velocity of a ball. In its explanation, it says:
The gravitational constant is represented by $g$.
Which "gravitational constant" is being referred? I want to believe it is referring to g... |
Does the second law of thermodynamics apply to parallel universes and universes of higher dimensions?
|
Suppose I have a state expressed in its eigenbasis as follows. $\rho = \sum_i\lambda_i\vert i\rangle\langle i\vert$. It is now measured in some other basis $\{\vert x\rangle\}$ that is distinct from the eigenbasis. Let this measurement operation be
$$M: \sigma \rightarrow \sum_x \vert x\rangle\langle x\vert \sigma \ve... |
Inside an insulated vessel at 1atm there is water at 100°C and a metal rod at 100°C, since temperature gradient is null there is no net heat transfer and water still liquid. In other words, in order to transmit latent heat, there must be a temperature difference. Am I right ?
|
So in this example I want to find the extension produced in the spring. The two methods are given in the image.( First one is by force method and the other one is energy method). The two yield different results. Where did I commit the mistake?
In the second method I have assumed that kinetic energy of the block is ze... |
I am currently sitting in a warm room. I just opened a window to the outdoors, where it is cooler.
Middle school science says the warm air should move toward the cool air, which should (in theory) result in equal temperatures inside and outside. How long should I expect that process to take?
For the sake of getting a ... |
Before/at/during the Big Bang, quantum fluctuations progressed until there was a constant energy density somewhere which caused inflation. The slight variations in energy due to those quantum fluctuations is now evident in the CMB. Thus, even the slightest energy differences developed patches in the Universe where gala... |
Say there is a conducting cylinder in a uniform external field. The charges on the cylinder surface will distribute and create a surface charge density.
Is there any reason the charge density would generally be uniform across the surface? We know: $$\sigma = \Delta E \cdot \varepsilon_0 \cdot \hat{n}$$ But what physica... |
I just read the Feynman Lectures about the electron gun experiment with two holes in the middle wall.
It demonstrates that if we don't look at the electrons while they travel toward the detector there is an interference pattern in the probability curve of the electrons similarly to what happens with waves. But if we tr... |
I’ve been reading about the conservation of momentum and its applications in deriving the rocket equation. I’m curious whether how can a rocket slow down in space. As far as i can comprehend, a rocket’s change in velocity is proportional to the negative of the exhaust velocity relative to the rocket and the ratio of th... |
If I had a set of measurements ,eg : $[10.0,11.0,11.5]$ and they each had a relative uncertainty of $10$% meaning my values are now $[10.0±1.0, 11.0±1.1, 11.5±1.15]$ how would I find the average of their uncertainties? Id think either one of two situations:
I simply add their uncertainties so that my new average value... |
In the Debeye approximation the density of states goes with phonon-energy^2, while the density of states for free electrons goes with sqrt(energy of the electrons), why is that?
(I use Introduction to Solid State Physics, Charles Kittel as learning book.)
|
In an introductory lecture on the path integral formalism, I came across the following. Suppose that $\gamma$'s are paths such that a particle travelling along any of them reaches the position co-ordinate (for simplicity, take it to be 1-d) $q_f$ at time $t_f$ from its initial state $(q_i, t_i)$. Every path $\gamma$ is... |
Given that the red shift of galaxies increases with distance, and that the light from further galaxies has taken longer to travel - then it seems that comparing red shift between galaxies needs to account for the difference in time that the light has travelled.
Is there a simple way to refute the argument that the re... |
I know an electron's charge is $~1.6 × 10^{-19} C$, which would mean that after leaving it would leave the droplets charge as $+1.6 × 10^{-19} C$ (right?) but I do not understand the effect of the ion on the charge of the droplet.
|
I was just trying to go over some of the contents in my exo planets course and wanted to know that if all the planets that form via core accretion continue to attract all the dust in a proto-planetary disk via gravity, till the star gets bright enough to expel the material, or if they gather most of their mass from the... |
I don't know if this question is better suited for this forum or math.stackexchange.com.
I come from a mathematical background and I'm struggling to understand a passage in Lipkin's book "Lie groups for pedestrians".
More precisely, I would like to understand what the following passage means in "more mathematical" term... |
I am familiar with isolated systems. They don't interact with the environment and no energy transfer takes place across the boundary of the system. My textbook says,
In an isolated system, if there are only conservative forces acting, its mechanical energy (potential & kinetic) is conserved. While, total energy (pote... |
I am following the Section 8.3.1 of Auerbach. I want to calculate spin correlation function via spin coherent state, i.e. the equation (8.28):
$$\begin{aligned}\left\langle\mathbf{S}_{m} \cdot \mathbf{S}_{n}\right\rangle=Z^{-1}\left(S+1\right)^2 \times \int \prod_{i} d \hat{\Omega}_{i}\left|\prod_{\langle i,j \rangle}(... |
I know that the differential equation that describes this kind of circuit is
$$\frac{d^2 q(t)}{dt^2} = -\omega^2 q(t) \, .$$
I was wondering how to model the case where we have dissipation of energy. I guess I should add some term of order $1$, but I don't know what to add exactly.
|
I am trying to understand all the forces on a person in a rotor ride appearing in the homework problem here.
It appear that the the normal force (due to contact between person and rotor's inner surface) provides the centripetal force. It is slightly difficult to visualize that there will be such a strong normal force (... |
A bow shock is a bow-shaped normal shock created around a blunt object flying supersonic.
The shock itself - mach = 1 - can be very hot at hypersonic speeds. But the subsonic air behind is cooler, which is why we use bow shocks on reentry capsules.
But why is this air cooler? Or, if it isn't, then why does the bow sho... |
I'm currently trying to calculate the expectation value
\begin{equation}
\langle\psi(p,s)|\bar{\psi}(x)\Gamma_\rho \psi(x)|\psi(p,s)\rangle,
\end{equation}
where $\Gamma_\rho$ is understood to be some unspecified string of gamma matrices and $\psi(x)$ denotes the fermionic field operator
\begin{equation}
\psi(x)=\int\... |
Please let me know if this is on the right SE site.
In a car suspension, the spring typically acts partway along the wishbone:
As such, there's formulae for working out the leverage ratio that exists in the suspension. The method I've been using involves the ratio between the length of the lower wishbone (d1+d2 in thi... |
how can a multi wall heat transfer problem with internal heat generation be solved? E.g.
|| heat generation ($\lambda_1,l_1,A_1$) | wall1 ($\lambda_2,l_2A_2$) | wall2 ($\lambda_3,l_3,A_3$) | $T_\infty,\alpha_\infty$
Heat flow is assumed only from left to right (positive x-direction) because of symmetric construction. ... |
We know that a metal paper clip floats on water when it is carefully placed over the surface. This is attributed to the phenomenon of surface tension. I understand that, due to its weight it creates a depression in the fluid as seen in the image below:
Image source: Wikipedia
Due to this depression, there exists a ver... |
I am beginning to study general relativity and one of the preconceptions that I have is that massive objects will warp space in a similar way to that described by the photo below
However my understanding is that massive objects in fact warp spacetime and that in a time and spatial coordinate system straight lines migh... |
I was thinking about acceleration due to gravity and I thought of deriving a formula that gives the net acceleration due to gravity between two bodies. Now, by net acceleration, I basically mean the effective acceleration. Please have a look :
Let $A$ and $B$ be two objects with masses $m_1$ and $m_2$ respectively
a... |
Let me get started with the origin of my problem :
Ammonia (considered to be an ideal gas) is initially at $T_1 = 25 ^° C $ and $p_1 = 1 $ bar is heated
at constant pressure until the volume has tripled. The heat capacity behaves according to the
equation :
$C_p^{0} = \text{some polynomial} $.
Calculate the molar hea... |
Why in a linear accelerator is used an AC voltage?
Wouldn't it work with a constant electric field?
(Image Source: <https://commons.wikimedia.org/wiki/File:Linear_accelerator_animation_16frames_1.6sec.gif> - Author: Chetvorno, CC0, via Wikimedia Commons)
|
Why is there an Event horizon of a black hole?
Why is it when something enters the horizon, it is inexorably pulled inside the black hole but not so if it hovers outside the horizon? How do we understand this?
|
Suppose that point c (i.e middle of the wheel as shown in the figure) is connected to the alternator.
for the first one minute the wheel is made to rotate in the direction A(i.e in clockwise direction) with 100 rpm(just assuming) and after one minute the direction of rotation is changed to direction B(i.e anti clockwi... |
I know that population inversion is achieved when the probability of stimulated emissions is greater than the probability of absorptions. But after the state is achieved, if $E_1 < E_2$ then what will be the probability of an atom wanting to excite from $E_{\text{1}}$ to $E_{\text{2}}$ versus the probability of an atom... |
In thermodynamics many definition has been made from partial derivatives at constant conditions for instance:
Let U be U:$f(S,V,m_k)$ then:
$$T = \left( \frac{\partial U}{\partial S} \right)_{V, m_{k}}; p = \left( \frac{\partial U}{\partial V} \right)_{S, m_{k}}; \mu_k = \left( \frac{\partial U}{\partial m_k} \right)... |
Consider a derivative coupling with $$\mathcal{L}_{int} = \lambda \phi_1 (\partial_\mu \phi_2) (\partial_\mu \phi_3),\tag{7.101}$$ and a scalar field
$$ \phi(x) = \int \frac{d^4p}{(2\pi)^3} \frac{1}{\sqrt{2\omega_p}} (a_p e^{-ip_\mu x^\mu} + a_p^\dagger e^{ip_\mu x^\mu}). \tag{7.102}$$
Using Feynman rules, the textbook... |
Among the (several) descriptions of an "inertial frame" (in the context of the Special Theory of Relativity),
those by John Norton and by Wolfgang Rindler appear especially concise:
"In special relativity, an inertial frame of reference is a congruence of timelike geodesics.",
John D. Norton, "General covariance and t... |
The Schwarzschild solution from general relativity defines the spacetime of a spherically symmetric body in a vacuum. During this derivation, the stress-energy tensor is set to zero and the solutions are obtained by solving the resultant differential equations.
As a thought experiment, imagine we have 2 stars (each is... |
When matter absorbs light waves does it cause the matter to increase in temperature? For example, microwaves can heat matter up, so can light waves do the same?
|
I took a photo of an amazing sight I had never seen outside my home ( southern india ) but I could not tell if it was a rainbow type thing or an aurora borealis. Can someone tell what this is and it’s reason of occurrence
|
In $AdS_5$/$CFT_4$, scalar fields of mass $m$ are mapped to conformal operators of dimension $\Delta$ via the dictionary:
$$\frac{m^2}{L^2} = \Delta(\Delta - 4)\tag{$*$}$$
From the string theory point of view one can realise $\mathcal{N}=4$ super Yang--Mills theory with gauge group $\mathrm{SU}(N)$ by considering type ... |
Airy wrote a paper (maybe deceptively) titled On certain Conditions under which a Perpetual Motion is possible (Cambridge Philosophical Transactions, December 14, 1829). Alternative site (in more than one sense) with JPEG images: https://www.besslerwheel.com/airy/. I've OCRed the (very legible) images and I can post th... |
If someone may, I expect a mathematical comparison of the governing equations "Maxwell Equations" for wave propagation and "Conservation of momenta & equilibrium equations" for stress and deformation. I am confused if a stress wave exists? If yes, how similar it is to EM waves?
|
I don't seem to fully get the mechanism going on. A potential difference is applied, then an electric field pushes electrons from low potential to high potential. Now, a few questions:
If electric potential is different between two different sides of a resistor (because there is a potential drop), does that mean bring... |
Suppose I have the EPR pair (maximally entangled state) as $|\phi\rangle$ and I apply an arbitrary matrix $U_3$ on the first qubit.
$$U_3 = \displaystyle \left[\begin{matrix}\cos{\left(\frac{\theta}{2} \right)} & - e^{i \lambda} \sin{\left(\frac{\theta}{2} \right)}\\e^{i \phi} \sin{\left(\frac{\theta}{2} \right)} & e^... |
Suppose a wheel is rolling without slipping down an incline. Static friction prevents the impending motion of the wheel relative to the incline. Since the slip is impending in the direction in which the wheel rolls, shouldn't the static friction point opposite to this direction or downwards along the incline?
|
From what I understand, if a gas has a temperature $T$ degrees Kelvin, it means that the probability of a gas particle to have energy $E$ is proportional to $\exp(-E/kT)$. It is the physical interpretation of temperature.
But it is only true when the gas is in Maxwell-Boltzmann Distribution. Electrons in plasma are in ... |
Dear physics stack exchange,
I've been trying to consider exactly how to program a gravitational simulation with time-retarded gravitational potential fields. Its proven difficult given each time one of the source masses is instantaneously accelerated the original sources potential fields spherically vanishes at a spee... |
Background: This question is inspired by Why is a relativistic quantum theory of a finite number of particles impossible?
1 - QFT is typically used to calculate relativistic scattering. The ground state of relativistic QFT is the vacuum, which is an invariant state under Lorentz transformations.
This is not the case wh... |
When finding the closest distance of approach of helium nucleus to the gold atom, we apply TME conservation. But the alpha particle is accelerated and hence, emits radiations. Why don't we consider these emitted radiations' energies and also, any magnetic field?
|
In the framework of relativistic quantum mechanics (not QFT) the Dirac equation in presence of external electromagnetic field is obtained by means of the minimal coupling, i.e. the substitution:
$$p_{\mu} \rightarrow p_{\mu}-eA_{\mu}$$
This substitution is often motivated by saying that it "ensures gauge invariance of ... |
I have a very simple question about incident an reflected waves. Consider for instance an incident light ray on an interface between two different materials. We know that there will be a reflected wave (with same angle of incidence) and a transmitted wave.
Let's focus on incident and reflected waves. My question is: do... |
I understand that quantum behavior is only apparent on the microscopic level, what then is the subject of Quantum Cosmology?
|
A source heats water inside a vessel (V=constant). As soon as boiling begins, pressure raise up. How will the system evolve? Depends on the heat?
How would be the relationship between the temperature (Cv) and pressure increasement as the steam (all steam under Tc) is being heated? May condensation occur?
I wrote water... |
I get how Teflon works, but am curious how the act of seasoning cast iron makes it non-stick. Does this also work for other metals besides cast iron?
|
Someone theorized on their blog, that if you would direct a 500 MeV proton beam into just air, it would create a glowing ball about 1.2 km from the target, with nothing inbetween. They theorized that this could be used to create glowing balls which can be mistaken for UFOs, because the plasma ball could move very fast ... |
I have three questions:
•) When is the Virial Theorem used?
•) Why is $n=-1$ in $V(r) = r^n$?
•) Also why is the average Kinetic Energy equal to half of the average negative Potential Energy?
I'm especially confused on the $n=-1$ part. Is it because when a system interacts with only gravity, we have to apply the equa... |
David Morin's book on classical mechanics is one of my favourite textbooks because of the amount of care that went into constructing the amazing end-of-chapter problems. I haven't found anything comparable in QM yet (where I am forced to think very critically about the problems, and the results are fun and elegant). I ... |
I am currently learning about the Dirac formalism in quantum mechanics, but don't quite understand how we derive the expression of the quantum Hamiltonian, given the value of energy in classical mechanics.
The specific example that came up in class was that of the harmonic oscillator, for which the classical energy is ... |
Is there a lossless way to combine light coming from two different single photon sources into one spatial mode? Either free space of fiber would be fine.
Let's assume the wavelength and polarization are the same in both input spatial modes.
The catch is that the intensity at the single output should be roughly the same... |
Is it known/proven what the smallest quantum error correction code is that can correct arbitrary two-qubit Pauli errors? I can think of the nested/concatenated 5-qubit code or a 25-qubit version of the Shor (repetition) code, but I am not sure if there are codes requiring fewer qubits.
|
I know if you have an acceleration as a function of $t$, $a(t)$, to find the velocity you simply integrate $a(t)$ with respect to $t$. Moreover, if the acceleration was a function of position, $a(x)$, you use the fact that $a(x) = v(x) \cdot dv/dx$ and solve for $v(x)$. However, what if the function of acceleration was... |
Serway's 10ed says that Newton's second law of rotational ($\sum \tau_{z} = I_{z}\alpha_z
$) is true when there is combined translation and rotation as long as the moving axis (1) passes through the center of mass and (2) is an axis of symmetry. Sears-Zemanski (edition 12) also adds that (3) the axis must not change di... |
As we all know, the magnetic field around a dipole looks like the following:
Notice how, directly above and below the magnet, the magnetic fields likes are parallel to the north-south axis. However, to the sides of the magnet, the magnetic field lines are anti parallel. If you've ever played with a magnet, you know th... |
There has been an emerging Hubble tension in which a cosmic-microwave background based estimation produces a value of about 67 (km/s)/Mpc while distance-ladder based methods cluster around 73. This difference isn't huge but it has reached a 5-sigma significance.
Many exotic particles, modified physics, and other phenom... |
The usual definition of radiation energy density in the context of statistical physics is given by
$$U=a_{B}T^{4}$$
With $a_{B}=7.5657\times 10^{-16} J m^{-3} K^{-4}$. So $U$ has units of $J m^{-3}$
On the other hand I read in some General relativity textbooks that the parameter $\rho$ (the parameter that appears in... |
The book Advanced Mean Field Methods mentions the following equation as a result of a "simple gaussian transformation".
$$
exp\left\{\frac{1}{2}\cdot\textbf{s}^T \cdot \textbf{J} \cdot\textbf{s}\right\} = \frac{1}{(2\pi)^{N/2}\sqrt{det(J)}} \int_{-\infty}^\infty \prod_i dx_i \exp\left\{-\frac{1}{2}\sum_{ij}x_i(\textbf{... |
I would like to know is there is a way to calculate (estimate) the leakage current for a diode?
|
Why potential difference across no resistance wire is same across two points.
|
For an ensemble characterized by the states $\{|n\rangle\}$ with probabilities $p_n$ at time $t$, the density operator is defined as $$\rho\equiv \sum\limits_n p_n|n\rangle\langle n|.$$ Assuming that the states $\{|n\rangle\}$ evolve according to the Schrodinger's equation but the probabilities $p_n$ are time-independe... |
I give my own answer below. I use the feynman rules for QCD directly to calculate the process: $qq'\rightarrow qq'$, where $q$ and $q'$ have different flavor. But I don't how to give my answer consistent with the standard answer.
It seems that the standard answer is based on the $SU(N_c)$ group?
|
A Problem is posed for a flight from Melbourne to Cairns.
Using the formula for rotational speed at latitude -
1) The latitude of Melbourne is approx 38 degrees south with a rotation velocity of 820 miles/hr
2) The latitude of Cairns is approx 17 degrees south with a rotation velocity of 994 miles/hr
The above two loca... |
I am assuming that i have a wheel of say 1 m radius. And it requires 10 hp(horsepower) to operate.
I found out that
hp= (Torque x rpm)/5252
So i am considering the case for rpm 60 and rpm 1500
for rpm 60:
10 = (T x 60)/5252
T= 875 N-m
and for rpm 1500 it comes out to be
T= 35.01 N-m
then we know that
torque= (radius)... |
I am calculating the loss power of a chilling pipe. The system has a fluid flow in with a temperature $T_{in}$ and constant speed $v$, then flowing out the system, and some high temperature $T_{bnd}$ boundary condition outside the pipe. Since the calculation is complicated, I have to use software to do the simulation. ... |
We have $2$ strings $|v\rangle$ and $\langle u|$,
String $-1$ :
$$|v\rangle=|e_{1}\rangle^{np}|e_{2}\rangle^{n(1-p)}$$
where :
$e_{1}$ occurs $np$ times
$e_{2}$ occurs $n(1-p)$ times
String $-2$ :
$$\langle u|=\langle f_{1}|^{nq}\langle f_{2}|^{n(1-q)}$$
where :
$f_{1}$ occurs $nq$ times
$f_{2}$ occurs $n(1-q)$ ... |
I am learning Length Contraction from the book Special Relativity and Classical Field Theory by Leonard Susskind.
There are two frames with relative speed $v$ along the x-axis. If my frame is at rest, then the other frame is moving with velocity $v$ towards right, i.e., towards the positive x-axis. The following pictur... |
Given a maximum deceleration of a car when braking in a straight line, what is the maximum deceleration of a car when it brakes and turns at the same time? I was thinking that maybe it had something to do with the angle of tilt of the tires changing the direction of the braking force, but I am not 100% sure, maybe some... |
I am going through Groenewold's theorem and in his book: On The Principles of Elementary Quantum Mechanics, page 8, eq. 1.30:
$$[\mathbf{p}, \mathbf{q}]=1\left(\text { i.e. } \mathbf{p
q}-\mathbf{q} \mathbf{p}=\frac{\hbar}{i}\right),\tag{1.30} $$
and he wrote:
The classical quantities $a(p,q)$ can be regarded as a... |
Imagine a perfect audio speaker creating a planar square wave - driven into a parabolic reflector.
The fundamental wavelength is around twice as wide than the parabolic reflectors diameter.
I've read that parabolic reflectors can only really concentrate wavelengths a multiple less than the radius of the reflector, with... |
We all know that the coherent state $|\alpha \rangle=\sum_n \, \frac{\alpha^n}{n!}\,(a^{\dagger})^n \, |0\rangle $ is an eigenstate of the annihilation operator: $a |\alpha\rangle = \alpha |\alpha \rangle $.
Lets say we have an operator which is a linear combination of permutations of creation and annihilation operato... |
Quoting the first sentence of the first postulate on wiki:
The electron is able to revolve in certain stable orbits around the
nucleus without radiating any energy, contrary to what classical
electromagnetism suggests. (https://en.wikipedia.org/wiki/Bohr_model#Origin)
My problem is the "contrary to what classical... |
Consider the 2 situations shown in the figure
In situation 2, it's quite obvious that T/2 is proportional to g. But, what I've come to know about situations like situation 1(here) is that- this tension T/2 is now proportional to (g-a) (called as effective g). Now this thing has totally confused me, how does situation ... |
So, most of the documents on the internet use Biot Savart law and integrate over length of the wire (from minus infinity to infinity) for an infinite wire magnetic field, but I have tried to integrate over the angle.
Here is how I do it. The point P is placed at radius R away from the wire.
The wire fragment $dl$ is a... |
Is it possible to generalize de density of states for phonons $\left( \left(\frac{L}{2\pi} \right )^3 \int \frac{dS_\omega}{v_g}\right)$ to a density of states which is also applicable to Bloch electrons?
I thought about changing $v_g$ to $v_f$ (the Fermi velocity), but that did not agree with de density of states for... |
Say there is a solenoid that creates a constant magnetic field in the space around it. An iron ball bearing is placed at one end of the solenoid where the field lines spread out. What would be the formula for the force on the ball bearing? I imagine it has something to do with the iron being assumed to be a collection ... |
I'm quite confused on the 'good' quantum numbers. I thought the good quantum numbers could be defined as the quantum numbers which corresponding operators commute with each other and the Hamiltonian. This definition seemed to work for me but the Zeeman effect is an exception.
First of all the Hamiltonian for the Zeeman... |
For example:
If the lift cylinder were $25 \text { cm }$ in diameter and the small cylinder were $1.25 \text { cm }$ in diameter, then the ratio of the areas is $400$, so the hydraulic press arrangement gives a multiplication of $400$ times the force. To lift a $6000 \ N\ $car , I would have to exert only $6000 N/400 ... |
I‘m currently taking Physics II and I have a conceptual question about SR in edyn.
Suppose I have two electron beams with linear charge density $\lambda$ paralell two each other in a resting system $S$ and each electron moves with a velocity $v$. Now I can calculate the electric and magnetic force between them, add the... |
The horizontal velocity that the ball acquires from the impact of your foot, will this be the maximum velocity, or will there be some horizontal acceleration at first, which results in a maximum velocity after which drag will slow down the ball?
|
I want to understand an experiment but I am struggling with the (basic) math/braket notation.
In the experiment two ions are entangled and separated into two wells $A$ and $B$. The spin state of the ions is thus $$\frac{1}{\sqrt{2}}\left[|\uparrow\rangle_A |\downarrow\rangle_B + |\downarrow\rangle_A |\uparrow\rangle_B... |
Short Version:
If we want to solve a problem where a particle is forced off a geodesic, can we obtain identical results if we instead solve the problem where the particle is in a different spacetime but stays on a geodesic?
Long Version (The Thought Experiment):
(See Twin Paradox for background)
Twin A is floating stat... |
Reading through Nielsen and Chuang, I came across the following example.
Consider a POVM containing three elements,
$$
E_1 \equiv \frac{\sqrt{2}}{1 + \sqrt{2}} |1⟩⟨1|,\\
E_2 \equiv \frac{\sqrt{2}}{1+\sqrt{2}}\frac{(|0⟩ - |1⟩)(|0⟩ - |1⟩)}{2}\\
E_3 \equiv I − E_1 − E_2.
$$
It is straightforward to verify that the... |
The argument I am trying to understand is the following:
For an orbit to be closed, the angle between successive perihelions (points where the planet at its closest to the sun) must be a rational number multiplied by pi :
$$ \Delta \phi = \dfrac{m}{n} \pi, \quad m, n \in \mathcal{N} $$
However, since the set of rationa... |
Let us assume you have a 3D bulk periodic crystal which has inversion symmetry e.g. $r\rightarrow -r$. Assume we are considering spinful operators with $S=1/2$.
Now let us imagine cutting a surface of this, lets say the surface $(x, y, 0)$. This surface should inherit the inversion symmetry of the bulk, e.g. it should... |
There are similar questions posted but unfortunately all deal with the case of no gravity.
I am trying to create a general model for the motion of a small bead of mass $ m $ which has been threaded onto a circular ring or radius $ r $ which is fixed in a vertical plane. The coefficient of friction between the ring and... |
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