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I want to simulate a circuit similar to the one below in MATLAB. If you have a state matrix describing the state of 3 qubits, I understand that you could apply a CNOT matrix tensored with and identity matrix to $\psi_{0} $ get $\psi_{1}$, but if you want to apply a controlled operation to the 1st and 3rd qubit to get $... |
I wondered if magnets could be used to hold a drop of molten liquid metal in air (not for any particular reason just because it could be done), but was disappointed when a quick Google search showed the metal would lose its magnetic traits before it melted.
Are there any other forces that could be used to suspend a dro... |
I may have confused after thinking too much about Faraday's law. If an emf is induced in a circuit due to some changing magnetic field, the induced current will be in a direction such that the "induced magnetic field" opposes the original magnetic field (Lenz's law).
So wouldn't the induced magnetic field also generate... |
What is the importance of dimension six operators in the study of physics beyond the Standard Model? Are these operators more relevant than dimension five operators like $HHFF$ or operators with derivative couplings?
I often see lagrangians with dimension six operators in effective studies of the standard model, but I ... |
In a 3D oscillator, the energy levels are known to be $(n_x + n_y + n_z + \frac{3}{2})\hbar \omega = (n + \frac{3}{2})\hbar \omega$.
Say for $n = 1$, any of the $n$'s can be $1$ and the rest are $0$. For $n = 2$ and $3$, same concept applies.
How do I use this information about degeneracy to suggest values of $\ell$ in... |
May be it is small question in this forum but I'm trying to get the feel of the understanding about the angular velocity. If this question is getting rejected please kindly refer me to appropriate forum.
From the definition of angular velocity the directory vector of angular veloticy is perpendicular to the plane of th... |
Suppose a paramagnetic solid is taken on the following cycle, where $B_1 > B_2$
(1)->(2)->(3)
I'm trying to explain what happens to occupation numbers in magnetic levels.
Step (1)
As $B_1$ increases to $B_2$, more spins get aligned due to the stronger field and entropy which is a measure of disorder falls. The occupat... |
Which textbook of differerntial geometry will have these formulas about conformal transformation?
$$\tilde g_{ij} = e^{2\varphi}g_{ij}$$
$$\tilde \Gamma^k{}_{ij} = \Gamma^k{}_{ij}+ \delta^k_i\partial_j\varphi + \delta^k_j\partial_i\varphi-g_{ij}\nabla^k\varphi $$
$$\tilde R_{ijkl} = e^{2\varphi}\left( R_{ijkl} - \left... |
I think I am currently making a mistake regarding my interpretation of Faraday's Law.
$\vec{\nabla}\times\vec{E}=-\frac{\partial\vec{B}}{\partial t}$
Assuming we have an electric field $\vec{E}$ in the plane between 2 particles given by:
$\vec{E}=(\frac{x}{x^2+y^2}+\frac{1-x}{(x-1)^2+y^2}, \frac{y}{x^2+y^2}-\frac{y}{(x... |
In my physics textbook it describes the events at the beginning of the Universe. I'm confused about the order at a certain point. It says that at some point primordial helium is created, then it says that later atoms are formed. Isn't primordial helium made of atoms?
Thank you :)
|
I have seen several claims to that quantum mechanics is required to explain the arrow of time which I take to mean the macroscopic irreversibility of physical systems. This is presumably to resolve Loschmidt's paradox. A recent example is a recent Simons Foundation article Time’s Arrow Traced to Quantum Source. Another... |
I have a farm situated right beside a canal through which we use to get water for our crops. I am not financially sound to buy an electric motor. The water is 15ft below the ground level. So can anybody suggest me a feasible way to get the water out of it by using air pressure or any simple instrument that helps me out... |
Steady flow is the condition in which the flow velocity profile does not vary with time.
Mathematically this is translated to $\frac{\partial \mathbf{v}}{\partial t} = 0$, for example in the derivation of Bernoulli's principle for the Navier-Stokes equation.
Why is it not $\frac{d\mathbf{v}}{dt}$?
I know the mathematic... |
If the Universe did start from a single point, then wouldn't all particles be fundamentally entangled? How then could there be a truly "pure" state?
|
My book doesn't explain well how to build a doublet of antiparticles that transforms the same way the particle doublet $(p,n)^T$ (proton neutron) does.
They claim $$\tag 1 \vert I=1,I_3=1\rangle = -p\bar n$$ for a composite nucleon-antinucleon system.
Why is $(1)$ true?
Perhaps it's just bad notation in the book? I ... |
How to show that $\hat {S}$-operator must be lorentz-invariant operator?
$$
|\Psi (t)\rangle = \hat {S} | \Psi (0) \rangle , \quad \hat {S} = \hat {T}e^{-i\int \hat {H}_{I}d^{4}x}.
$$
I have read that this result follows from the unitarity of the Poincare group operator $U_{0}(\Lambda , a)$ and the covariance of S-matr... |
Imagine a particle tracing a counter-clockwise circular path on a flat table with a certain speed. The particle is tied with a massless string of length $R$ to a point $P$ at the center of the circular path. Will the particle rotate about $P$ forever at constant speed in the absence of any external force? Consider usin... |
I am wondering how you can determine the path of a particle in a velocity selector provided its velocity doesn't equal $ \frac{E}{B} $. I understand that the equation is derived from this force equation,
$\sum \vec{F} = qvB- qE = ma$,
where $a = 0$, but I cannot show analytically how its path would differ should its ve... |
Let's say I have a single particle hamiltonian in a periodic potential, for example a 1D lattice such that:
$$H = -\frac{\partial_x^2}{2m} + V(x) $$
with $ V(x+a) = V(x)$ where $a$ is the lattice spacing between the atoms or sites.
It is known by Bloch's theorem that a solution to such a system will have the form
$$\p... |
The answer is C, but I got B...
F at 3cm = 10, F at 6cm = 20
$W=F\cdot s$
$(20-10)\times 3=30$
I must have made a mistake or stupid assumption then, how am I meant to get 45 N cm?
|
I'm trying to obtain the Feynman Green Function (i.e. I'm using the Feynman Causal prescription to compute the green function) for the D'Alembertian in 1+1D, I'm finding
$$G^{(2)}_F (t; \vec x) = \frac{1}{4\pi} \frac{\Theta(t^2-\vec x^2)}{\sqrt{t^2-\vec x^2}} - \frac{i}{4\pi^2} \int_{-\infty}^\infty dz' \text{P.V.}\lef... |
Suppose there is a person standing in a Merry go Round, which is rotating at a constant angular velocity $\vec \omega$. He experiences, of course, a centripetal acceleration $\vec a_{cen}$ and has some tangental velocity $\vec v_{tan}$.
This person now starts to walk in a circular path against the direction of rotation... |
I am trying to formulate the wave function that describes two entangled electons having the same position but opposite spin. According to the Pauli exclusion principle this should be possible. And when their spin would be equal, the wave function would cancel out and become 0.
I tried:
$\psi({r}_1,r_2,s_1,s_2)=\psi_a (... |
Recently, I was reading about Hawking Radiation in A Brief History of Time. It says that at no point can all the fields be zero and so there's nothing like empty space(quantum fluctuation etc.). Now, the reason mentioned was that virtual(force-carrier) particles cannot have both a precise rate of change and a precise p... |
Particularly in the case of Majorana neutrinos, it seems a little odd that the particle and antiparticle would have differing cross sections.
Perhaps the answer is in here, but I've missed it:
http://pdg.lbl.gov/2013/reviews/rpp2013-rev-nu-cross-sections.pdf
In the caption of figure 48.1 of the PDG excerpt linked above... |
The answers to this question explain that ice is less dense than water because it has a "crystal structure", but they dont explain what exactly that is and why this happens, also I saw this answer from another site stating that not all ice is less dense than water.
What is the "crystal structure" that ice has? Why is i... |
They say that all colors can be formed by mixing Red, Green, and Blue appropriately. Is it true? Isn't the Fourier basis infinite dimensional? Or does it turn out to be the case that only three frequencies happen to reproduce most of the colors in the visible range?
|
Setup
Imagine a two-body system of masses under a classical mechanics model. The separation and mass-ratio doesn't matter for this example. Presume they are initially stationary.
Now suppose that we hold one of the masses, m1, permanently stationary with an external force opposing the gravitational force due to the sec... |
This is a paragraph from my book:
"For a damped system, the resonant frequency at which the amplitude is a maximum is lower than the natural frequency.However, maximum transfer of energy, or energy resonance always occurs when applied frequency is equal to natural frequency"
This doesn't make intuitive sense to me. I u... |
When double-slit diffraction occurs, there are interference patterns inside, say, the central diffraction maxima (or envelope). I am trying to understand how these interference fringes are created.
Here is what I know: each individual slit in the double-slit setup produces a diffraction pattern, and these two diffract... |
The text, see [1], compares the vortex solutions of a spontaneously broken symmetry $U(1) \rightarrow 1$ and $SU(2)\rightarrow U(1) \rightarrow \mathbb{Z}_2$. The vortices can be classified by elements in the first homotopy group which are respectively $\mathbb{Z}$ and $\mathbb{Z}_2$.
My questions
What do they mean by... |
I am trying to solve a problem where I need to find the distance travelled at the end of the nth second and my input data contains only velocities at different time instances.
Say for instance I would like to find out the distance travelled at the end of the 5th second with the given data where each row corresponds to ... |
It's not homework (I'm teacher). I would like to compute sum of forces on this study :
The shape is symmetrical like that I'm sure the center of gravity is in the center of the shape. I compute forces on axis $X$ only. No external gravity. Air container are fixed on big container. But air container has very low pressu... |
A car is moving at a velocity of $10 \, \text{m}/\text{s}$. After point $A$ no acceleration is provided. By simple measurement, the acceleration is found to be $-1 \, \text{m}/\text{s}^2$.
Using standard equations: $$v = u + at, \; v=0, \; u = 10, $$ we arrive at $t = 10 \text{s}$.
$$S = ut + .5 at^2 = 50 \,\text{m}$$
... |
I have a problem regarding computation of spin connection in the case where One or more dimension is compactified. For example if we take a $D+1$ dimensional bosonic string action and write the $D+1$ dimensional metric in terms of $D$ dimensional fields,and we want to compute the spin connection then how to exactly do ... |
So I am dealing with the following hamiltonian, and the following perturbation:
$$H=-\mu B_0\sigma_z$$
$$V=\mu B_1(\cos(\omega t)\hat x-\sin(\omega t)\hat y)\cdot{\bf \sigma}$$
I am asked for the probability that the spin will go from ground state at time 0 to the excited state at time t using first order time dependen... |
So I know:
$$[\sigma_{I},\sigma{j}] = 2i \epsilon_{ijk} \sigma_{k}$$
So two products of this should give us the Lorentz group:
$SO(4) = SU(2) \times SU(2)$
Where $SO(4)$ has 3 Lie algebra which can be expressed as one by denoting:
$$J_{I}^{\pm} = \frac{1}{2} (J_{I} \pm ik_{I})$$
This gives two Lie algebra:
$$[J_{I}^{\p... |
If, in a QFT of a scalar field $\phi$, a Fock space $n$-particle position eigenstate $\lvert x_1\cdots x_n\rangle $ is given by
$$
\lvert x_1\cdots x_n\rangle =\hat\phi^\dagger(x_1)\cdots\hat\phi^\dagger(x_n)\lvert 0\rangle \,,
$$
where $\lvert 0\rangle $ is the vacuum state, then we have
$$
\langle x_1\cdots x_n\lvert... |
We can define a probability distribution over phase space (say 1D) $\rho(x,p)$ such that, for example,
$$\langle x\rangle = \int x \rho(x,p) dxdp$$ etc.
It can be shown here that such a distribution satisfies (analogously to fluid dynamics) $$\frac{d\rho}{dt} = 0$$ and therefore $$\frac{\partial \rho}{\partial t} = - \... |
What is meant by incompressible flow?
The density of the fluid is a constant, $\rho = constant$
The density of a fluid has a spatial dependence but remains constant in time, $\rho = \rho(\mathbf{r})$
In both cases $\rho$ should satisfy $\frac{d\rho}{dt} = 0$ right?
(In case 1 is true, how do you call a flow with the ... |
I know it's probably the most stupid question there is, but why do they fly are the clouds lighter than air? What's keeping those tiny ice structures floating miles about the ground? I've been looking all over the internet and I can't find acceptable answer to this basic physical question. Can you please help me?
This ... |
I have done my experiment using water ripple to study the behavior of waves. I know that the crest will absorb more light than the trough so that the image created on the white paper sheet appeared to be the troughs has darker lines than the crests. However now I wonder why the crest of water absorb more light than the... |
I have a time series of kW where each sample is measured at regular intervals (10 seconds). Could anyone explain to me how could I calculate the total power consumed (kWh) over an hour?
Thanks
|
I know that when a body is is equilibrium
There is zero resultant force in any direction, i.e. the sum of all the components of all the forces in any direction is zero
The sum of the moments about any point is zero (this point does not need to be on the body)
What if the body is not in equilibrium?
Let me clarify: Wh... |
Boltzmann's definition of entropy is $\sigma = \log \Omega$, where $\Omega$ is the number of microstates consistent with a given macrostate. If I understand correctly, this means that it only makes sense to speak of the entropy of a physical system with respect to a definition of the "macrostate" of the system. For exa... |
If an electron is in $s$ state, for example in 1s state for Hydrogen or 5s state for Silver atom, $\ell=0$. So,its total angular momentum $L$ is also equal to 0. So, what is electron actually doing in s state. Is it actually not moving at all. I know that it has got spin, but if it is not moving, doesn't it violates un... |
I'm reading Rubakov's "Classical Theory of Gauge Fields", and I'm having a little bit of trouble with problem 7, p 15:
Using an expression of the type $E = \int d^{3} x \frac{\delta L}{\delta \dot{\varphi} (x)} \dot{\varphi} (x) - L$, find the energy of an electromagnetic field with action $S = -\frac{1}{4} \int d^{4}... |
In fact, this problem is more likely to be a math problem.
When I read a paper(http://arxiv.org/abs/0707.2875), the author includes the characteristic polynomial for a type of matrix $A_k$ with eigenvalues $E_k$.
The characteristic polynomial is expressed as
\begin{equation}
\rho(E_k) = E_k^4 - (\text{Tr}\{A_k\})E_k^3 ... |
While certain classes of systems that exhibit topological order can be solved exactly (such as the Toric Code, Abelian FQH Edges, etc.) there also exist systems
(think of perturbed versions of the Toric Code or Abelian FQH Edges) that cannot be solved exactly.
What are the common numerical tools that are used to extr... |
Since l=0 for a valence electron in 5s state of silver, L=0 and therefore magnetic dipole moment is also 0 which means that the beam should not have deflected at all. So, we introduced the property of an electron called spin which explains the deflection. However, my problem is How the introduction of spin explains the... |
Imagine you have two homogeneous spheres with the same diameter of $d=0.1 m$. They have the same mass $m = 1 kg$. The distance between the centers of mass is $r= 1 m$. Their electrical charge shall be disregarded. At $t=0$ the spheres do not have any relative motion to each other. Due to gravitation they will accelerat... |
I believe that answer to my question is rather trivial but I can't seem to get my head around it. In the context of the ADM formulation of gravity (or any other differential geometry context, I guess) the covariant derivative of a normal vector to the hypersurface/foliation/slice, in any direction within the hypersurfa... |
Since a matter wave is associated with a particle in quantum mechanics, does the wave spins? I mean, can we visualize the spinning of wave or is it possible that the wave spins?
|
Why don't people discuss the eigenstate of the field operator? For example, the real scalar field the field operator is Hermitian, so its eigenstate is an observable quantity.
|
What effects does the raising level of CO2 in the atmosphere have, besides being a greenhouse gas and responsible for the increased acidity of the oceans?
What other environmental damages does it cause?
|
$$\left[J_i,J_j \right]=i\epsilon_{ijk}J_k$$
$$\left[J_i,M_j \right]=i\epsilon_{ijk}M_k$$
$$\left[M_i,M_j \right]=-i\epsilon_{ijk}J_k$$
where $J_i$ is the generator of rotation of Lorentz group, $M_i$ is the generator of boost of Lorentz group
In many textbook of QFT, they say that the second one implies that the gener... |
A tight string lies along the positive x-axis when unperturbed. Its displacement from the x-axis is denoted by $y(x, t)$. It is attached to a boundary at $x = 0$. The condition at the boundary is
$$y+\alpha \frac{\partial y}{\partial x} =0$$
where $\alpha$ is a constant.
Write the displacement as the sum of an inc... |
We know that the molecule of hot water($H_2O$) has more energy than that of cold water (temperature = energy)
and according to Einstein relation $E=mc^2$ ,this extra energy of the hot molecule has a mass.
Does that make the hot molecule heavier?
|
Supersymmetry should cancel the radiative corrections to the Higgs mass and solve the hierarchy problem. If Supersymmetry would be unbroken, would the higgs mass be 0?
|
In condensed matter physics, especially in the context of superconductors, if an author uses the phrase "charged order parameter", what does it refer to? Since the superconductor has a close relation with high energy physics, I think it may come from quantum field theory.
Could someone give me a hint?
|
OK, so my textbook says that in time dilation and length contraction, the proper time and the proper length is "That which is in the frame of reference of the observer at rest relative to the event".
This means that the proper time/length is that which is observed by the observer moving close to the speed of light, an... |
Ok, although this question arises out of the global warming debate, this is a question purely for physicists and not intended to branch into that particular debate.
We are told that LWIR from the Earth to the atmosphere is absorbed by greenhouse gasses and then re-radiated (in the form of backradiation) partially to th... |
I am confusing between non linear dynamics and chaos. Chaos is also a non-linear dynamics right? then what is the difference between chaos and non-linear dynamics?
What I understood about chaos is that, it is some errors or small deviations which repeat itself in space-time and with time it amplifies. Also, this depend... |
I'm new to physics and am just going through some of the free online classes at World Science U, and after watching this video on the nature of the speed of light and its constancy, a question came to mind about photons. (Video: YouTube Video, World Science U course)
I know that photons don't have mass, but what ha... |
In inflationary theory, many papers start off by making the slow-roll approximation, on which many things depend. This approximation is usually presented by requiring that two 'slow-roll parameters' are small:
$$\epsilon_V\equiv\frac{1}{16\pi G}\left(\frac{V'}{V}\right)^2 \ll 1$$
$$|\eta_V|\equiv \frac{1}{8\pi G}\left(... |
In Polchinski's String Theory, section 6.2, the tree level amplitude for open strings with higuer vertices are given (6.2.18-20).
The amplitude
$<\prod_i[e^{ik_i\cdot X(z_i,\bar {z_i})}]_r\prod_j\partial X^{\mu_j}(z_j')\prod_k\bar \partial X^{\nu_k}(\bar z_k'')$>
yields result
$\text{other terms }\times <\prod_j[v^{\mu... |
I have two metallic spheres each with a charge of $q_1$ and $q_2$ respectively. What is the value of $$\varepsilon_0\int_{\text{all space}} \vec{E}_1\cdot\vec{E}_2 \,{\rm d}v$$
where $\vec{E}_1$ and $\vec{E}_2$ are the electric fields due to the two spheres and $\varepsilon_0$ is the permittivity of free space. The rad... |
I am wondering how the relative humidity affects the vaporization?
I saw on an other post that it doesn't affect it, but in my personal experience, it takes much more time to dry clothes when the relative humidity is high, so it's hard for me to believe that it does not have a big effect. What is the effect of relativ... |
https://www.youtube.com/watch?v=Ucdw0DDI4n8
I've seen another variation where the whole match stick turned to ash.
What's going on in this trick?
|
A bird of mass $m$ is on a merry-go-round of radius $a$ which rotates at constant angular velocity $-\omega_b$ in the $y$ direction. A woman of mass $M$ is on a second merry-go-around of radius $b$ which rotates at constant angular velocity $\omega_s$ in the $z$ direction around the same origin. At $t=0$ the bird is at... |
In canonical quantization, we view the Dirac field $\psi$ as a $4\times1$ matrix of complex number. While in path integral quantization, we view the Dirac field $\psi$ as a Grassmann number.
For two Grassmann number $\psi_1$, $\psi_2$, we can calculate $\psi_1\cdot\psi_2$ and it has the properity $\psi_1\cdot\psi_2=-\p... |
Ok this is a silly question but here it goes
Although it is good to have a laminar flow of the air around the object for low drag but the laminar flow is prone the phenomena called separation (sounds like breakup) which dramatically increases the drag on the object. On the other hand turbulent flow has a greater drag a... |
The ladder paradox consists of a ladder rushing towards a garage with two open doors. In the actual paradox, proper length of the ladder is greater than that of the garage, but in this case lets consider them to be of the same proper length.
In the frame of the garage, the ladder is Lorentz contracted, and hence it is ... |
The Lagrangian with Lagrange multiplier in the form
$$L= T- V + \lambda f(q, \dot{q},t).$$
But there are different ways of writing the constraint $f = 0$.
Will that lead to different EOMs?
Let me give an example:
A pendulum with mass $m$ and length $\ell$.
We can use let
$$I=\int_{t_0}^{t_1}\left[\frac{1}{2}m(\dot{x}^2... |
What is the reason Schroedinger equation is quoted in terms of potential energy instead of force?
|
The mass of a particle appears in Schroedinger equation but it does not appear its charge, although both terms have their effect on movement.Why?
|
As I know, the fundamental concept of QFT is Renormalization Group and RG flow. It is defined by making 2 steps:
We introduce cutting-off and then integrating over "fast" fields $\widetilde{\phi}$, where $\phi=\phi_{0}+\widetilde{\phi}$.
We are doing rescaling: $x\to x/L$: $\phi_{0}(x)\to Z^{-1/2}(L)\phi(x)$.
This p... |
The thought experiment goes like this:
Say there is some circuit which turns a lamp on/off with just a flick
of a switch. Say its off; you flick it, it turns on; flick it again it
turns off, and so on.
So say you are conducting the experiment for two minutes. When the
remaining time halves, you flick the switc... |
This might be a stupid question but given Einstein's general theory of relativity $E = m c^{2} $ what is the energy of a black hole? Isn't the mass of a black hole infinite? Wouldn't that be infinity multiplied by the speed of light squared?
|
I'm not sure why the fermi surface crosses the Brillouin zone boundary at right angles. I understand that this is normally the case, but not necessarily always.
I'm aware that the fermi surface is a constant energy surface up to the filling point. The Brillouin zone is in reciprocal space.
|
Asked to find the tension of a point that is halfway up a rope (where the rope has mass), given the system:
The solution to the problem (FBD included) is as follows. In this diagram ($T_m = $tension at mid-point, and $T_t =$ tension at the top).
Question(s):
(1) Why is $T_t$ incorporated into the FBD?
(2) Why does $... |
I know that if a star collapses into a volume with radius less or equal to the Schwarzschild radius $r_s=\frac{2GM}{c^2}$ then a black hole is created and it has the same mass of the star that gave it origin. But is there a way to calculate the mass of a black hole without knowing the volume of the star?
|
I am reading the Feynman lectures and at this point http://www.feynmanlectures.caltech.edu/I_13.html#Ch13-S3 it says as follows:
The time derivate of the potential energy is
$\begin{equation}
\dfrac{d}{dt}\sum\limits_{pairs}-\frac{Gm_{i}m_{j}}{r_{ij}} = \sum\limits_{pairs} \left( +\frac{Gm_{i}m_{j}}{r^2_{ij}} \right)... |
I want to calculate the expectation value of a Hamiltonian. I have a wave function that is $$\psi = \frac{1}{\sqrt{5}}(1\phi_1 + 2\phi_2).$$
I want to know if I set this up properly. The Hamiltonian is $\hat H \left(x, \frac{\hbar \partial^2}{2m\partial x^2}\right)$. To get an expectation value I need to integrate th... |
Suppose we have an atom. It is commonly said that because of the PEP, two electrons can't be in the ground state unless they have opposite spins, because no two electrons can have the same wavefunction.
What bugs me is that spin up and spin down aren't the only possible spin states. There's a whole continuum of linear ... |
I know that matter can be converted to energy through E=mc^2.
I also know that engery can be and has been converted to information through Landauer's principle (with Maxwell's demons).
Does this mean that I can take a brick and covert it into information? (It is irrelivent if there is no known process yet)
|
Consider a point-mass $m$ having constant velocity but undergoing influence from two forces, $F_1$, $F_2$, having equal magnitude but opposite directions. Because the forces' magnitudes are equal, I would expect no net acceleration of $m$, but if $m$ is moving, the forces are doing work on $m$ ($F_1$'s work being the i... |
Do all forms of energy have a mass? We know by $E=mc^2$ that mass and energy are directly proportional, but there are massless forms of energy such as electro-magnetic waves. I am also told that there are different forms of mass, such as invariant mass, virtual mass, and relativistic mass. This electro-magnetic wave se... |
Is there a fundamental difference in the definition of entropy when considering the classical thermodynamic picture vs. the quantum mechanical picture, or are they both fundamentally equivalent?
|
I am trying to find the following dipole moment matrix element $(|n,\ell,m\rangle)$.
$$e\langle1,0,0|\vec r|2,0,0\rangle$$
I believe that I can say this matrix element is zero because of parity. The wavefunctions have parity $(-1)^\ell$ and seeing as each has $\ell =0$, they are even parity. Then r is odd, as it send... |
If a jet takes off from an aircraft carrier, should it not already be traveling at the speed of the carrier. Also, does the jet require more energy to get off the carrier than from a stationary base?
|
Consider an unormalized wavefunction of a rotor at $t = 0$, a combination of $n=0$ and $n=2$ states:
$$\psi(\phi) = 3 - 2 \cos (2\phi).$$
Find the probability distribution in angle.
The book simply takes probability as
$$\lvert\psi(\phi)\rvert^2 = \lvert 3 - 2\cos(2\phi)\rvert^2 = 9 + 4\cos^2(2\phi) - 12\cos(2\phi).$... |
What is the age of the Universe from the big-bang light perspective?
We all agree that the universe is around 14 billion years, from the perspective of a hypothetical observer moving in a galaxy, e.g. ourselves.
But what would be the age of the universe from the perspective of the first light that emerged from the big ... |
What would happen if the second law of thermodynamics was not there for governing in every day processes. Can a universe exist and evolve if the second law of thermodynamics does not exist in first place?
|
I recently saw a cat fall probably 100 feet like in this video Cat Falls. It seemed as if the cat reached terminal velocity by the time it hit. Does this mean that cats (and other small animals) could fall any distance without much harm because of there low terminal velocity? Is there a point when (in increasing animal... |
I understand that, broadly speaking, Poynting's theorem is a statement of conservation of energy.
Energy density of a volume of current and charge decreases proportionally to work done on charges within the volume and by energy flux through the surface bounding the volume.
The energy flux term is the area integral of t... |
Assume I use a coil to create B-flux and put ONE Neodymium cylinder magnet (1" diameter & 0.25" thick) close to the flux, it would create 10 lbs of force. Does that mean that putting TWO cylinder magnets (1" diameter & 0.25" + 0.25" = 0.5" thick) would create 20lbs of force?
|
The property of hermitian is the sufficient condition for eigenvalue being real.
Is there any non-hermitian operator on Hilbert Space with all real eigenvalues? If there exist, then can all eigenstates be orthogonal to each other? And these operators have any application in Quantum mechanics?
|
For example, a leaf in normal sunlight may be seen as green, but under a red light it is seen a red or may be dark. So the color of leaf changes according to lighting conditions. So that, does any substance possess the property, Color?
|
So, I was reading the paper by Fidkowski and Kitaev on 1d fermionic phase http://arxiv.org/abs/1008.4138. It explains the classification of 1d fermionic SPT phases with $\mathbb{Z}_2^T$ symmetry for both the interacting and non-interacting cases.
I understand why we had a $\mathbb{Z}$ classification in the non-interac... |
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