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Required to do a physics practical experiment for a year project and I decided to do something regarding ion thrusters.
My idea was to create a simple DIY ion thruster (can be seen below) and put it under a vacuum as I feed it with different gases. I knew that the general principle of how ion thrusters work is by ioniz... |
What does a photon carry from its parent particle that when it interacts with another particle, it entangles both the particles?
|
I want to integrate a differential distribution function of sterile neutrinos and the boundaries are the decoupling and the reheating temperature of neutrinos, but I don't know what is an acceptable value for a reheating temperature.
In most sources the neutrino's $T_{\text{decoupling}}$ $\approx 1 \text{MeV}$ (p14 sec... |
I did google this up but found nothing! I can't be the first to ask (the vague question)
"What is the half life of a gravitating three-body system?"
CLASSICALLY this means: Say I have three classical point particles of the same mass $M$ and start the system with some random initial conditions (pick whatever "good" dist... |
Pin is kept in front of a concave mirror at a distance $x$ . Observer shifts his gaze towards the left,the inverted image of pin appears to the right. Then $f<x<2f$ .
Here I understand that the rightward shift is because of parallax. I am confused as to why it will be seen only when $f<x<2f$ , as from what I've seen ... |
The Hubble mirrors are two hyperbolas.
I see on Wiki the formulas for the Ritchey–Chrétien telescope.
https://en.wikipedia.org/wiki/Ritchey%E2%80%93Chr%C3%A9tien_telescope
My question is how is the shape of the hubble mirrors calculated?
|
Disclaimer: I am not quite sure if this question belongs to Physics SE, if not feel free to move it.
Question:
I am currently using the VEGAS-algorithm (See e.g. here and here) and i am trying to understand how it works. But in the paper "A New Algorithm for Adaptive Multidimensional Integration" by G. P. Lepage [J. Co... |
Consider the Boltzmann equation in the case of a homogeneous position distribution.
$\frac{\partial f(p, t)}{\partial t} = \mathcal{Q}^{ee}[f](p)$
where $\mathcal{Q}$ represents the collision integral. I would expect this to take the form
$\int dw(p, p' | q, q') f(q)f(q') d^3q d^3q' - \int dw(q, q'|p, p') f(p) f(p')d^3... |
Lets say that we have a point charge $q$. Let's draw a Gaussian sphere at a distance $d$ from the charge, as no charge is enclosed inside the sphere the integral
$$
\oint_A \vec E \cdot \text d \vec A = 0
$$
vanishes.
Hence electric flux at that point is zero. Now I understand that flux through an external point is zer... |
I am very confused by the statement made in Haag's, Local Quantum Physics: Fields, Particles, Algebras (page 46):
... the idea that to each particle there is a corresponding field and to each field a corresponding particle has also been misleading and served to veil essential aspects. The rôle of fields is to implemen... |
Why the mass spring system prefers to oscillate at natural frequency, why does it rather oscillate at other frequencies? Every object in the universe is always vibrating, is it true? if it is the mass spring system at equilibrium, the atoms/molecules inside the systems are still vibrating with a natural frequency.
|
Consider a simple mass-spring system. The spring is attached to the ceiling in the lab frame of reference and a block of mass $m'$ is suspended from the spring. The mass starts to oscillate with simple harmonic motion of period $T'$ in the lab frame of reference. If the spring constant is measured to be $k'$ by the lab... |
In standard quantum mechanics, the wave function have discrete energy-values due to a potential. However, my very limited understanding of QFT is that electrons are excitation in the Dirac field, and the number of electrons is discrete even in free space. What is the reason for this, and why is there a minimum excitati... |
I am a bit rusty on GR, I have the condition $u_{\mu}u^{\mu} = -1 $, in some notes I am given that we can obtain:
$$-1 = u^{2}_{t} [g_{tt} +2 \Omega g_{t \phi} + \Omega^{2} g_{\phi\phi}]. \tag{1} $$
The metrics in question are Kerr and Schwarzschild in Boyler Linquidist coordinates. I am also given for stationary obser... |
Sir $P=F/A$
And since $F$ and $A$ both are vectors but $P$ is scalar. So doesn't it violates that "Division is NOT defined for vectors"?
|
Two charges $+q_1$ and $-q_2$ are placed at A and B respectively, A line of force emerges from $q_1$ at angle $\alpha$ with line AB. At what angle will it terminate at $-q_2$?
My approach: Since no of field lines originating or terminating at a charge is proportional to its charge itself, I have assumed the charges ... |
Discussions in comments below How can aerogel be lighter than air? really make an answer to this important. The conclusions there are that aerogel could in some cases be "lighter than air" if one takes only the mass of the aerogel material and ignores the mass of any trapped gas within each cell, and divides by the vol... |
When we put two bodies with different temperatures in contact, there will be a heat transference between them. The variation of the entropy of the system is well known (this is computed in most physics textbooks). However, I was thinking: in the beginning, when we put the bodies in contact, the total system will not be... |
In a question, I was given that $a^{\dagger}a + a a^{\dagger} =1$ and asked to show what $a|n\rangle$ and $a^{\dagger}|n\rangle$ would be, given that $H|n\rangle=(a^{\dagger}a + 1/2)$.
I am getting the wrong answer for $a^{\dagger}$.
Call number operator $N=H-1/2$ and denote anticommutator by $\{\}$.
$\{N,a^{\dagger}\}... |
How is an optical chopper eliminating drift? Or in more concrete words: Why is a chopped signal eliminating drift (DC -> AC)?
|
I was reading Isham, Chris J. Modern differential geometry for physicists. Vol. 61. World Scientific, 1999. p.52
In the first chapter, he gives mathematical preliminaries that'll be useful for the rest of the
chapters. There I came across this interesting text about open sets and their role in physics.
An important qu... |
I recently asked a question in quantum computing stack exchange and as suggested by someone in the comments, I decided to ask my question here as well:
I know that for a given spin-j quantum state, say $\vert\psi\rangle = (\psi_0 , \psi_1 , \cdots , \psi_{2j})$, we can construct a polynomial as follows
$
w(z) = \sum_{k... |
I've been trying to learn about things like thermionics and vacuum tubes but I've run into something that doesn't make a whole lot of sense to me. So, assuming I'm not totally backwards in my understanding of conventional vs. electron current: an anode is where the conventional current enters and the electrons leave a ... |
As the universe expands, wouldn't we need more dark energy pumped into the space to keep the universe expanding. If so, where does the new dark energy come from?
|
The Lorenz gauge is the only Lorentz invariant electrodynamic gauge. If the vector potential has physical meaning, as in the Aharonov-Bohm effect (ABE), then the gauge condition can not be arbitrarily chosen and Lorentz invariance seems gone.
How can the integration path in ABE be Lorentz invariant?
|
My question relates to magnetism and classical electrodynamics.
The following is a reference. This question says $\downarrow$ (do not answer to this):
$N$ sources of current with different emf's are connected as shown in
the following figure The emf of the sources
are proportional to their internal resistances, i.e.... |
Background
From what knowledge of quantum mechanics I have so far, it is a postulate that Hermitian operators corresponding to a certain observable act on a quantum state $\psi$ to produce a new quantum state. The eigenstates of these operators are the states with a definite value for the observable and the eigenvalue ... |
I am paraphrasing the following fact from Srednicki's Quantum Field Theory textbook. For an infinitesimal Lorentz transformation $\Lambda^a_b=\delta^a_b+\delta\omega^a_b$, we associate the unitary operator $U(1+\delta\omega)=I+\frac{i}{2\hbar}\delta\omega_{cd}M^{cd}$.
Is $U(\Lambda)=U(1+\delta\omega)$ supposed to be a... |
As the universe expands, the (not co-moving) distance between any two points, say the distance between galaxy A and galaxy B, increases.
Assume the universe behaves the same way in all directions.
$D(t)$ is the distance between galaxy A and galaxy B.
$E(t)$ is the distance between galaxy A and galaxy C.
If $E$($t$=refe... |
What are the immediate advantages of the Lagrangian formulation compared to the Newtonian formulation to give high school students a little connection to what they'll find in universities? I can't use derivatives, integrals, ODE, ecc... but very few elementary concepts.
Are there advantages to solving dynamic or kinema... |
In Shigley(5th Edition), in Chapter 14. Dynamics of Reciprocating Engine ,Section 14.7 Inertia Forces,
the inertia torque exerted by the engine on the crankshaft is given as
$$
\mathbf{T}_{21}^{\prime \prime}=-\left(-m_{B} A_{B} \tan \phi\right) x \hat{\mathbf{k}}
$$
Background : In this section they have assumed equi... |
As far as I can tell, groups that measure the Hubble Constant usually measure galaxy recession speeds $v$ and galaxy distances $d$. Then they plot one versus the other and the best-fit slope is the Hubble Constant (or its inverse).
Except what they plot isn't really $v$ vs $d$ (or $d$ vs $v$), it's $cz$ versus $d$ (or... |
"Quasiparticles" are ubiquitous in condensed matter physics, e.g. magnons and phonons, and more generally all particles in quantum field theory are considered the elementary harmonic excitations ("vibrations") of the quantum fields. The classical analogues of these concepts are plane-wave excitations which are manifest... |
Mirror surface flatness is specified as a multiple of $\lambda$, where $\lambda$ is the wavelength at which the surface flatness was tested, and is typically $\sim 632\ nm$. A $4\lambda$ surface flatness beam might not work so well in certain applications with a $632\ nm$ beam. Would the effect of surface flatness incr... |
What is the highest and lowest frequency EM wave detected? In theory, the maximum possible EM radiation must have a wavelength greater than Planck length. However, is there any maximum possible wavelength? Also, how charged particles block the very low-frequency radio waves from entering Earth?
|
I am trying to understand renormalization in Wilson approach.
There's cool picture, which demonstrates flow of theories in IR:
So, if one interested in UV limit, one need reverse flow and flow in this reverse direction.
As it clear from picture, this procedure can be done only for red line. Dashed or solid line will l... |
I've already made a post about this topic here, but I realized that I didn't understand the explanation on that post. in Chapter 7 of Rindler's book on relativity, in section about electromagnetic field tensor, he states that
and introducing a factor 1/c for later convenience, we can ‘guess’ the tensor equation, $$ F_\... |
Consider the Friedmann equation with no radiation:
$$
\frac{H(t)^2}{H_0^2} = \Omega_{m,0} a^{-3} + \Omega_{k,0} a^{-2} + \Omega_{\Lambda,0}
$$
We can have values for $a(t)$ and the density parameters such as the right hand side of the equation is negative. That would imply an imaginary Hubble constant. Is there any phy... |
Reading the book called "The great design particles fields and creation" one finds the following paragraph
In a universe like ours, constructed of electrically charged elements, magnetism and the magnetic field can be considered a relativistic consequence of
the electric field. If the speed of light were infinite, or ... |
How to derive the matrix form of the translation operator? If $T_x$ is the matrix form of translation along $x$-axis and $T_y$ is along $y$-axis then what will be the translation matrix on the $xy$-plane.
|
Using homogeneity of space, isotropy of space and the principle of relativity (without the constancy of light speed), one can derive:
$$x' = \frac{x-vt}{\sqrt{1+\kappa v^2}}$$
$$t' = \frac{t+\kappa vx}{\sqrt{1+\kappa v^2}}$$
$\kappa = 0$ denotes Galilean and $\kappa < 0$ denotes Lorentz Transformation.
What does $\kapp... |
As explained by Maxwell, (1875), a realistic thermodynamical system will, at low temperature, have pressure vs. volume curve that is non-monotonic. In practice, though, the observable states of the system will lie along a straight line of constant pressure, where part of the system is in the condensed liquid state and ... |
I am little bit confused about the term anti-symmetric tensor. $$p_{ijk\ell}$$ is an anti-symmetric tensor. I would like to know its value when any of the two indices are same. For example, Is $$p_{1123}=0?$$
Also, do you have a good reference to cite these properties?
|
I understand Current density $J =n e v$ [$n=$ carrier concentration per unit volume, $e=$ charge on electron, $v=$ drift velocity]
Which is independent of area of cross section of wire (and hence the diameter)
However, the book practical electronics for beginners quotes that:
Current density within a copper wire incr... |
My Physics teacher made the statement in a recent class.
"A concave mirror always forms a real image of a virtual object"
But, what did he mean by a virtual object? What does this statement exactly mean?
PS : I have just started learning geometric optics.
|
We all are aware how we can use the forces and vectors to describe a classical projectile motion (No drag forces).
Major things we already know include:
Position-time dependence of projectiles
Range of projectile
Distance traversed by projectile
Curvature at any point
My question relates to a 3D-Geometrical interpret... |
My basic understanding of the Unruh effect is that an accelerating observer will experience black-body radiation proportional to the magnitude of the local acceleration, while an observer in an inertial frame will not.
If A is in an inertial frame and observes B in an accelerated frame, A must observe the effect of Unr... |
People have explained how time flows but not why time flows or how time flow is possible at all. How does science explain time flow?
|
Suppose we have a density operator given by $\rho=\mid \Psi \rangle \langle \Psi \mid$ with $\mid \Psi \rangle = \frac{1}{\sqrt{2}}(\mid 1 \rangle\mid \ 0 \rangle-\mid \ 0 \rangle \mid 1 \rangle)=\frac{1}{\sqrt2}(\mid 10 \rangle-\mid01\rangle)$ living in a space like $\mathcal{H_s}\otimes\mathcal{H_a}$, where 1 and 0 a... |
As I understand it a blackbody spectrum is continuous – every possible frequency between the upper and lower bounds for that specific spectrum is there. When we look at the sun (mainly hydrogen) or a tungsten filament (comprised of one element only) we observe a continous spectrum between the upper and lower frequency... |
If we suppose that light is made of small elastic particles, does the classical Galilean relativity explain the Michelson-Morley experiment?
I would greatly appreciate any point of view.
|
Physically, a photodiode and a photoconductor base on the same principle: Lifting charge carriers from the valence into the conductor band.
As this principle is already used in photoconductors which, if I understood correctly, are only made out of a single doped material, I wonder, how photodiodes benefit from being co... |
Wikipedia is talking about two ways of interpreting this effect.
The classical way is simply calculating the intensity-fluctuation-correlation. But what is here the difference between a laser and a thermal source?
For the QM interpretation they refer to the two-photon interference. What is this?
As I understand:
Thinki... |
I've been reading about why voltage drop occurs and that electrical potential energy supplied to an electrical charge is lost after work is done, but my question is that after this potential energy is lost, how does current continue to flow without this potential energy pushing it?
For example, $12V$ are applied to a l... |
Suppose I have a particle in 2D cartesian space. It has an equation of motion which is straight line.
If I change the co-ordinate (Say Polar co-ordinate), will the equation of motion will be straight line or not?
If No: What is intuition behind this?
|
I've been going around in circles (hah) about how gauged cosmic strings work (I've been using Preskill's notes for the most part). The global string scenario makes sense to me, since different points on the vacuum manifold are physically distinct. But I'm uncertain about vacua which would seem naively to be indistingui... |
If we work in an experiment similar to that of Michelson-Morley and we assume that light is made up of small elastic particles, and we make light beams reflect multiple times from moving mirrors, could they, according to classical relativity, travel to
speeds much higher than $c$?
Any idea is welcome and appreciated.
|
In many introductory books on electrostatics, you can find the statement that the field inside a conducting shell is zero if there are no charges within the shell. For example, if we place an uncharged conducting sphere in a uniform electric field we would get something like this:
For simplicity, I have drawn a unifor... |
So I'm trying to find the equations of motion of a field in a particular metric. I know what the equations of motion of the field in flat space look like and how they simplify. I think it's always valid to go to normal coordinates, but it just seems suspect to me at the moment although I'm not sure why.
The equation of... |
Suppose, I have two conductors $A$ & $B$. $A$ has a higher potential than $B$. Now, let us connect the two by a wire.
Electrons will now move from $B$ to $A$. Now, my question is that will the kinetic energy supplied per electron be the same? One may say that it is, and the magnitude of the energy per coulomb of elect... |
Consider two fluids $F_1$ and $F_2$ with equal volume and heat capacity as well as $T_1$ and $T_2$ respectively, whereby $T_1 > T_2$. One uses a Carnot cycle to transfer heat from $F_1$ to $F_2$ in small cycles such that the temperatures after a certain amount of cycles are equal $T_1 = T_2 = T_0$. Now, I want to find ... |
I am unable to find images of pure crystalline graphite with high confidence, but based on various sources I believe that it should actually be both black and shiny, in the sense that it reflects much less visible light than a white piece of paper, and yet has a much more metallic sheen than paper. For example, this we... |
I just studied Heisenberg's uncertainty principle in school and I came up with an interesting problem.
Assume an electron which is moving very slowly and we observe it with a distance uncertainty of say $\Delta x=1\times10^{-13} \text{ m}$ if we try finding uncertainty of velocity using the formula $$\Delta x \cdot ... |
In the context of an Open Quantum System (OQS) i.e. a quantum system coupled to a quantum environment, what is really meant by information backflow from the environment to the system? I'm newly exposed to this field and learning basic standard stuff related to the formalism. Looking forward to a simple explanation.
Mor... |
What is the result when a photon doesn't hit the pn-junction? Can't it be lifted? From my understanding there should be valence and conductance bands everywhere across the material. Nevertheless, I'm quite certain the effect will be different when lifting an electron within the scr region and in case not?
source: http... |
I was playing a game when I started thinking about this problem:
Say, a person is sandboarding down a hill/dune, right before the slope begins,
what are the conditions that must be met in order for man and his
board to stay in contact with the ground, like:
What should be the maximum velocity of the man+board system b... |
If they can, can I use the potential energy equation to find out how much the temperature would increase if 1 kg of water is dropped to the ground from 10m height?
|
There are a lot of questions about this topic on this site, none of them answer my question specifically.
I have read this question:
What does a photon emitted by an atom "look" like?
I think of the emitted photon as a point particle (but with a polarization vector) traveling in a straight line from the atom to the me... |
I was studying Barbara Ryden book on modern cosmology, on it's 5th chapter, she introduces the following image:
This image summarises the general behaviour of the Hubble constant. I was wondering, what is the best way to reproduce this plot. For instance, taking the Big bounce case, disregarding radiation, one could s... |
What I know is current density is the amount of current passing per unit area perpendicular to the current. But then why do we define it as the rate of change of current with respect to change in area $\left(\dfrac{di}{dS}\right)$.
Aren’t they both two different things?
I’m a high school student. It’s given in the book... |
Not long ago someone (here) asked a question about engine block water cooling, suggesting that the advection equation might be of use for that problem. I understood this not to be the case and promised a different kind of approach. But I defaulted on that promise when I realised just how complex this problem is.
Ever ... |
I was following Section 5 of Ridley's book "Quantum Processes in Semiconductors" where he tries to derive transition rates for a system interacting with harmonic (cosine) potential. For simplicity lets write it in a form:
$$
\langle f|H_I|i\rangle =C e^{-i t \omega }+C e^{i t \omega }.
$$
Now he says that "investigat... |
Let's assume we are in a perfect vacuum and let a photon travel from a point $A$ to a point $B$. As far as my understanding of quantum physics goes, the photon takes all possible paths between $A$ and $B$, as shown in this picture:
Here, I have drawn 3 possible paths $a$, $b$ and $c$. Path $a$ goes directly from $A$ t... |
Under my understanding of integrability, a system with $2n$-dimensional phase space is integrable when there are at least $n$ constants of motion satisfying some conditions (e.g., they are in involution). I have been trying to check my counting to see why the two body problem is integrable while the three body problem ... |
A civil nuclear reaction remains on the principle that uranium fission drives to production of neutrons that then create another uranium fission and so on. The reaction is controlled by various mechanism (bore, temperature, etc.).
But then, in a civil nuclear reaction, how the very first nuclear fission or uranium star... |
In particle physics, is the rate of the reaction $a+b\rightarrow c\rightarrow e+f$ the same as the one of $e+f\rightarrow c\rightarrow a+b$ ?
If so, then what does prevent that the final states goes back to the initial state, so that we never observe the final state ?
|
What determines the height at which a superconductor levitates? Can you just place it randomly in the magnetic field? What are the limits of superconductors?
|
For fun, I created a 3d gravity simulation and colored each $(x,y)$ coordinate blue or green if a light mass put at that location would collide - within some number of simulation steps - with one of the masses of a binary system of two heavy masses, with its center of mass at the center of the image.
The result looks v... |
Consider the interacting field Lagrangian density of the real KG field
\begin{equation}\mathscr{L}=\frac{1}{2}\partial_\mu\phi\partial^\mu\phi-\frac{m^2}{2}\phi^2-\frac{\lambda}{4!}\phi^4
\end{equation}
The generating functional for the theory is
\begin{equation}
W[J]=\int\mathscr{D}\phi(x)\exp\left(i\int d^4x\left[\fr... |
I'm working on a problem where we find the probability of finding a particle between $a/4$, and $3a/4$. The particle is confined between $0$ and $a$.
Normally I would attack this by normalising the wave function, solving for $A$, and then using that value in the next steps to find the probability between a given range.... |
This may sound trivial but I wanted to make sure I did not misunderstand. I know that the conservation of energy is always true even in cases where energy appears to be lost (when in reality it is just converted into heat, sound etc.). However, my question is does the conservation of energy hold when there are unbalanc... |
I have been told that I can describe a system by its wave number states:
$$|k_1\rangle|k_2\rangle,$$
and that the following is true:
$$|k_1\rangle|k_2\rangle=|k_1+k_2\rangle|k_1-k_2\rangle,$$
I am aware that the ket notation represents vectors but I am not too familiar with it, I was just wondering if this is some form... |
The Feynman propagator for a massless point particle is proportional to:
$$\Delta(x-y;t_1-t_2)=\frac{1}{|x-y|^2-(t_1-t_2)^2}$$
which is, formerly, the Fourier transform of $\dfrac{1}{|k|^2-E^2}$.
For a bosonic string given by the coordinates $X^\mu(\sigma)$ and $Y^\mu(\sigma)$ with $\sigma \in [-\pi , \pi]$, what is th... |
Do the active quarks mean valence quarks? Or we can also consider other quarks, like when there are offshell-quarks produced from gluons by pair production processes?
For example: how the active quark is different than the other valence quarks?
|
Four rigid rods, $OA$, $AB$, $BQ$ and $CD$ are connected as shown in figure. All functions are movable $C$ is mid point of rod $AB$ and $C$ is movable link. The end $D$ of rod $CD$ is constrained to move vertically. For the position shown angular velocity of rod $OA$ is $60\ \text{rev/min}$ clockwise. If $OA$ = $1$ $m... |
For a conventional soap bubble which burst very easily, mostly due to water evaporates or run into things that corrupt the surface tension.
Would it be feasible to make a machine that keeps humidity and floating air such that the bubble is always floating and last forever ?
If not what is the bottleneck ?
|
I'm not really knowledgeable on physics but was curious about this and couldn't find any good answers related to it.
|
I understand that this happens due to Kirchhoff's law. Any current entering one side of the capacitor must have come from another part of the circuit connected to the other side.
But is there an alternative explanation for the above phenomenon which doesn't involve Kirchhoff's law?
|
I've heard many about the idea of flat band,but I'm still confused.
We've learn the idea of band from solid state physics. It has origin in ignoring the Coulombic interaction and diagonalizing the momentum operator. That's based on the fact that interaction is small.
How ever,in flat band,the effect mass is quite large... |
So we can derive this expression by equating force of attraction on the electron by the nucleus to the centripetal force acting on the electron, i.e: $$ \frac{KZe^2}{r^2}= \frac{mv^2}{r},$$ where $m$ is the mass and $e$ is the charge on the electron, $Z$ is atomic no. of the $H$-like particle, $K$ is the Coulomb consta... |
In the realm of magnetostatics, consider the integral form of Ampere's law:
$$ \oint_C \mathbf{B} \cdot d\mathbf{l} = \mu_0 I_{enclosed}$$
What I realized is when asked the question "what is the enclosed current enclosed by?"
The most common answer I get is "enclosed by the Amperian loop of course!"
I think this is a h... |
I currently need a guide on how to calculate the energy deposition on material surface using SRIM/TRIM software.
|
I watched a presentation where special relativity was mentioned as being essential to understand electromagnetism, as in the case of current flowing in a cable, a charge moving next to the cable, due to length contraction of SR feels one charge more than the other.
I also read electromagnetism was later quantized throu... |
I'm looking for a quantitative (and accessible) description on the scattering of NIR light (850 nm) by pure water. More specifically, I want to find how much of the incident 850 nm light beam is scattered onto a given direction per meter of pure water.
I found that two processes, the Rayleigh scattering and the Raman s... |
I already had a question about the Hanbury Brown Twiss effect, but this question is actually a seperatre question:
Here I red following:
The HBT effect comes from the interference of different but
indistinguishable two-photon probability amplitudes22,23,24. If these
two ways are distinguishable, even in principle, the... |
I am currently looking at a paper (C. Ortix, "Quantum mechanics of a spin-orbit coupled electron constrained to a space curve", Phys. Rev. B 91 (2015) 245412, arXiv:1504.00840) where spin-orbit coupling (SOC) in quasi-one-dimensional quantum wires is studied. The starting point is a SOC Hamiltonian
$$
H= \frac{\mathbf ... |
Port Beirut disaster (ammonium nitrate explosion, 4 August 2020) was equivalent to 1.15 kt of TNT (4.4 TJ). It falls in the range of a small nuclear device (20 t TNT for the smallest, 15 kt TNT for Little Boy, which was dropped on Hiroshima).
What is the difference between such an explosion, and a nuclear device of a s... |
A block placed on movable smooth inclined wedge placed on a smooth surface. Both are released and allowed to move.
I was told that
If the center of mass of wedge and block system is fixed (in the horizontal direction I assume, otherwise there won't be any motion) then in the journey of the wedge from A to B the Normal... |
Consider the following hypothetical experiments in quantum physics:
Experiment A:
Consider four 'shells' in a line (see here for inspiration for name), and there are four different colour peas/particles under them, say red, yellow, green, blue, and an observer can make a measurement by lifting up a given shell and obse... |
On page $41$ Landau states that the total momentum in the C system is $0$.
On page $43$ for the disintegration of many particles, Landau states: In the C system... every resulting particle (of a given kind) has the same energy...
Why is this?
I understand why the statement is true if the momentum of a primary particle ... |
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