0
votes
1answer
27 views
Wave function interpretation $y(x,t) = (0.35m)\sin(10\pi t-3\pi x + \frac\pi{4})$
Wave function interpretation $y(x,t) = (0.35m)\sin(10\pi t-3\pi x + \frac\pi{4})$
I used to deal with function with one variable
And now theres are two, how can I interpret them?
Is $10\pi$ still ...
4
votes
2answers
57 views
How to directly calculate the infinitesimal generator of SU(2)
We commonly investigate the properties of SU(2) on the basis of SO(3). However, I want to directly calculte the infinitesimal generator of SU(2) according to the definition $$X_{i}=\frac{\partial ...
0
votes
0answers
19 views
UV light penetration into silicon
I'm in need of some information about UV (particularly UVA) light's ability to penetrate into silicon. Specifically, I am looking for a relationship between wavelength and penetration depth. Also, if ...
0
votes
1answer
22 views
Magnetic engine
Is it possible to mimic crrent engine design (to some extent) by replacing the cylinders with opposed magnets? A device interupts their natural desire to push away from each other allowing them to ...
2
votes
0answers
43 views
Cosmic Inflation: Lower Expansion Rate with than without?
When I read the Cosmic Inflation diagram at
https://en.wikipedia.org/wiki/File:Horizonte_inflacionario.svg
which I rotated to make it readable:
where the Hubbleradius, and therefore also the ...
3
votes
2answers
39 views
Stable Nuclei - Deviation from equal protons and neutrons
While studying the semi-empirical mass formula for nuclei, I came across an "asymmetry term" whose function, as far as I understand, is to build in the fact that nuclei "prefer" to have equal numbers ...
0
votes
1answer
39 views
Relativistic Lagrangian transformations
I need to study the relativistic lagrangian of a free particle.
It's
$\ L= - m c^2 \sqrt[2]{1- \frac{|u|^2}{c^2}} $ I need to study the translation, boost and rotation symmetry. I say it doesn't ...
0
votes
0answers
19 views
Specular intensity [closed]
Im currently studying for an exam and have been going through some past papers on the subject, however i have come across a question that has recursively come up each year and the notes on it are not ...
3
votes
1answer
93 views
Is electromagnetism a dead research field?
Are there any phenomena, we consider as electromagnetic and have no explanation for ?
3
votes
3answers
43 views
Showing Hubble constant is time-independent
I have the following question for homework:
Show that the Hubble constant $H$ is time-independent in a universe in which the only contribution to energy density comes from vacuum energy.
So in ...
0
votes
1answer
31 views
Optical element fitting to Jones matrix
I need help with finding out which optical element is this.
I read about Jones matrix and vectors, but this is not one of the standards.
$$
\begin{pmatrix}
1 & i \\
-i & 1\end{pmatrix}
\cdot ...
1
vote
1answer
50 views
Lie algebra of lorentz group
I'm stuck in following calcualtion from sredniki's QFT book.(Its actually in the solution manual)
How can i get from
$$\delta\omega_{\rho\sigma}(g^{\sigma\mu}M^{\rho\nu} - g^{\rho\nu}M^{\mu\sigma})
...
22
votes
12answers
1k views
Quantum mechanics and everyday nature
Is there a phenomenon visible to the naked eye that requires quantum mechanics to be satisfactorily explained? I am looking for a sort of quantic Newtonian apple.
4
votes
2answers
46 views
Equivalent RC circuit to a RRC circuit?
I'm in doubt about a situation that I've seen sometimes: imagine we have a resistor in parallel with a resistor and a capacitor in series. Since I don't know how to generate figures of circuits to ...
0
votes
0answers
28 views
electrostatic repulsion [closed]
Consider a homogeneous ring of radius $R$ made of a thin wire of cross section $A$ with $R^2≫A$. A charge $Q_1=10\mu C$, uniformly distributed over the ring, broke it apart due to electrostatic ...
2
votes
0answers
55 views
Categorizing solutions to Hierarchy problem
We know that no gauge symmetry can prevent a term $m_\phi^2|\phi|^2$ for a scalar field, and that, given the quadratic loop corrections, the natural scale is $m_\phi \sim M_P$. This is related to the ...
0
votes
0answers
38 views
An application of Toeplitz operators
I want to find an application of the Toeplitz operators. All I need is a known problem (not an open problem) which solution use the theory of Toeplitz operators. I don't need all the details but I ...
2
votes
0answers
23 views
How to numerically solve a laser driving semi-classical two-level system using Floquet formalism?
Consider the semi-classical laser driving two-level atom, where the laser is treated classically and the atom is treated quantum mechanically. The effect of laser on the atom is a dipole coupling:
$$
...
-2
votes
1answer
39 views
A double-sided lever and multiple forces [closed]
Assume a double-sided lever where the left arm has a length of a and the right arm has a length of b + c. Please refer to this ...
0
votes
1answer
41 views
Difference between velocity vectors, relative speed
Consider two particles moving in the same direction instantaneously but one of them follows a circular path and one follows a straight path.
If I adopt a rotating frame of reference in which the ...
0
votes
0answers
39 views
How does the volume change affect an adiabatic process?
A gas consisting of rigid diatomic molecules was initially under standard conditions. Then the gas was compressed adiabatically, 5 times the original volume. Find the mean KE of rotating molecules ...
0
votes
0answers
31 views
Historical aspect of wave theory of light
Huygens thought light as a wave. Wave is a propagation of physical disturbance. We now know that light is electromagnetic field. Electric and magnetic field fluctuates here. What Huygens really ...
0
votes
2answers
50 views
Dividing values with units
I'm reading about the subject of heat in a basic physics book. If I am not mistaken the formula to work out how much energy is required to increase the temperature of water is
...
2
votes
2answers
43 views
What really is the Magnetic Force on a wire?
I have a doubt regarding the significance of a force on a wire. Well, first of all, I know that if I have a particle and if there are several forces acting over it, then we can compute one total force ...
0
votes
0answers
34 views
Derivative of $\epsilon$ in lennard jones equation
I just want to calculate the derivative of epsilon for the following Lennard Jones equation:
LJ = $4\sqrt{\epsilon_{ii} \epsilon_{jj}}$ $[(\sigma/ r)^{12}-(\sigma/r)^{6}]$ with respect to ...
3
votes
3answers
149 views
How does relativity explain gravity, without assuming gravity [duplicate]
I have seen the "objects pull down on space-time" explanations, but they assume a "pull down" force themselves. Could anyone explain the space-time explanation without assuming gravity in the first ...
2
votes
2answers
68 views
Interpretation of de Broglie wave
Until what point can the de Broglie wave be thought as a real wave?
I mean, is it made of something?
What amplitude does it have? Is it a sine wave?
How can it be related to the wavefunction of the ...
0
votes
1answer
40 views
How does gravity effects both time and light if they have no mass [duplicate]
I've been reading about how black holes can effect both time and light with gravity. So I was wondering, doesn't something have to have mass to be effected by gravity? And if so, does this mean both ...
7
votes
1answer
90 views
What is the reason that relativistic corrections for hydrogen atom work?
Here I cite part from Sidney Coleman's lectures on Quantum Field Theory:
It is a phenomenal fluke that relativistic kinematic corrections for the Hydrogen atom work. If the Dirac equation is used, ...
2
votes
2answers
54 views
2-D Orientational Order Parameter
I am building a computational model of ellipsoidal cell network formation and I would like to use a particle order parameter to study my model's behavior. I have come across this article Steinhardt, ...
0
votes
0answers
21 views
Is a dynamical extension of non-commutative black holes feasible?
Non-commutative (sometimes called "fuzzy") black holes are solutions of Einstein's equations obtained with a previous basic assumption of non-commutativity of the coordinates $[x^{\mu},x^{\nu}]=i\, ...
0
votes
0answers
44 views
Gradient involved commutator in $\phi^4$ theory
In a phi fourth theory, the Hamiltonian density is:
$$\mathcal{H}=\frac{1}{2}\pi^2+\frac{1}{2}(\nabla \phi)^2+\frac{1}{2}m^2\phi^2+\frac{\lambda}{4!}\phi^4$$
Now I impose the usual equal time ...
1
vote
1answer
47 views
Interaction strength in BCS theory
I'm looking to plot the band gap $\Delta(T)$ as a function of temperature between $T = 0$ and $T = T_c$ by numerical evaluation of the band gap equation
$$\frac{1}{\mathcal{N}(0)V} = ...
0
votes
0answers
14 views
What is the “relative permeability” of Neodymium?
I am currently interested in finding a high "relative permeable" material to put into the core of a solenoid. However many sources quote Neodymium's recoil realtive permeability ($\mu_{rec}$) to be ...
-2
votes
0answers
29 views
About machine having efficiency infinite [closed]
I do not have any idea, about how to share my view but it is possible to make machine having efficiency infinite. From last 12 years I am constantly working on it and i have found a solution but up ...
-2
votes
0answers
19 views
Circuits using generators and cells and capacitors [closed]
This question was in a science worksheet we had, the description read as follows:
Tim has designed a generator that uses wind power and provides 9V. He decides to design a circuit using diodes ...
5
votes
2answers
66 views
Calculating the the kernel using path integrals for quadratic lagrangians
I am reading Feynman and Hibbs on Path Integrals. In section 3.5, they show that the kernel for a lagrangian of the form $L=a(t)\dot{x}^2+b(t)\dot{x}x+c(t)x^2+d(t)\dot{x}+e(t)x+f(t)$ is ...
0
votes
0answers
30 views
fast quantum random number generator + limited decoherence rate => Schrödinger cat state?
Suppose that fast quantum random number generator (QRNG, https://qrng.physik.hu-berlin.de/) is placed in a subsystem which has limited interaction with
the rest of the world. What would happen if ...
3
votes
2answers
54 views
Does the slip-stick phenomenon have any application?
The slip-stick phenomenon is present all around us, be it the noise of car breaks or in earthquakes. But does it have any real-life application?
1
vote
2answers
57 views
How & Why does accelerating charges radiate electromagnetic radiation?
Lets consider it case by case:
Case 1: Charge particle is at rest. It has electric field around it. No problem. That is its property.
Case 2: Charge particle started moving (its accelerating). We ...
-2
votes
0answers
27 views
Finding Clebsh-Gordan coefficient [closed]
Two electrons , their angular quantum number =1 . Find the inner product of < 2 0 | 00 > ?
1
vote
4answers
84 views
How does moving charges produce magnetic field?
I'm tutoring High school students. I've always taught them that:
A charged particle moving without acceleration produces electric as well as magnetic field?
It produces electric field because ...
0
votes
1answer
35 views
Calculating vector components from other vectors
I'm busy studying for my Physics exam this evening and I've come across a vector problem that I cant quite solve. Any help would be appreciated!
We are given the following vectors:
...
-3
votes
0answers
19 views
Lowest attenuation at 1550 nm for link lengths in 30-50 km range [closed]
Could someone point me to a reference that features the lowest-possible loss value (as of today) for transmission of light at ~1550 nm? In particular, the typical length of the optical link is in the ...
3
votes
2answers
89 views
Imaginary time in QFT
I'm reading chapter 4 of Introduction to Quantum Field Theory by Peskin & Schroeder. In the $\phi^4$ theory, the authors state that the ground state of the interaction theory $|\Omega\rangle$ can ...
0
votes
1answer
25 views
Kinetic energy when $F(t)$ graph is given
The very basic problem here is that the point where this graph ends is ambiguous. I mean, what is the corresponding $y$-value for the point whose $x$-valu is $4.5s$? Then I think we should find the ...
0
votes
1answer
25 views
Eigenvector Grover Operator
I have a question about the eigenvectors for the evolution operator of Grover's algorithm. Let $U=R_DR_f$, where
$$\begin{align*}
R_D &= 2|D\rangle\langle D| -I_N , \\ R_f &= ...
0
votes
0answers
19 views
How to make a fan like behavior [migrated]
I am making a game in Unity. I have an object e.g. cube. I want to release air from it like fan so that when other cubes come closer, it throws them away. What velocity,force etc I will need to do ...
0
votes
1answer
38 views
Relative Velocity problem
I was solving many problems on relative velocity and observed that when the question asks,
"what is the minimum time taken by the boat/man to cross the river.?"
so the solution says that he ...
0
votes
1answer
39 views
Eigenvalue $a_n$
Q1:
In Zetilli's book page 166 (ch. "Postulates of QM", eq. 3.1) i encountered an expression $\hat{A}|\psi\rangle = a_n|\psi_n\rangle$. I know this is an eigenvalue equation, but i have seen another ...
