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I was looking at Heisenberg's uncertainty problems and came across a question asking for the linewidth of an emitted photon. I seem to remember that linewidth is measured in units of energy but I am unsure how to go about calculating it.
|
All the basic texts say $dQ = T dS$. Some say it is possible to define absolute entropy. That source gives an equation integrating C dT which should reduce to $Q=ST$, if $S(0) = 0$ and $Q$ is defined as all the heat that can possibly be extracted from the object. But it seems like sources overwhelmingly avoid writin... |
In engines we have air and a hydrocarbon. Once we want to go forward we open the box containing it and the oxygen reacts with the hydrocarbon giving some gases. Due to the fact it is an exothermic reaction heat is released which heats up the gas and therfore the pressure of the gas is increased. And from that point it ... |
This is sorta a cross-post from my post in StackOverflow. Although, rather than seeking help with the code I'm here asking for help with a physical/mathematical/statistical problem associated with the code.
I'm trying to cluster infrared (IR) spectra so that spectra most similar to each other are grouped and processed ... |
Since the rise of temperature in a body is measured by its specific heat capacity, will my measurement of a body's temperature changes if i use a different thermometer rather than the usual mercury thermometer
|
Why use sine and cosine to find the components of a vector? To find the cosine and sine, the point must not belong to the circumference and it must be giometric? So why do we use sine and cosine?
Do you have an in-depth guide so you can study mechanics, electromagnetism, optics .... quickly?
|
I know that general relationship between the frequency $f$ of the photon, the potential $U$ and thw work function $\phi$ is given by:
$$eU=hf-\phi$$
I wondered if this relationship would be still true if we accounted for relativistic electrons? I'm sadly not that strong in speical relativity and searching on the web fo... |
Being uniform, one can denote the magnetic field $\vec B = (B_x, B_y, B_z)$, where all $B_i$ are constants. I know that the particle inititial velocity is $\vec v_0$ - I will use this later when integrating. The particle has charge $q$ and mass $m$.
Here, I can use Lorentz force ($\vec E = \vec 0$, because $B$ is no... |
Is the disappearance of liquid rain water at < 100 deg C (< 212 deg F) @ atmospheric pressure after it stops raining and the sun comes out an example of evaporation and/or diffusion mass transfer?
|
This is a follow up to my previous question Why is the kinetic energy for non-relativistic velocities not described by $KE=mc^2$?
After trying to use the actual formula for relativistic kinetic energy
$$KE=(\gamma - 1)mc^2$$
where $\gamma = \frac 1 {\sqrt{1-\frac{v^2}{c^2}}}$, I tried to do some test calculations to co... |
Is light shifted 180 degrees out of phase, when it is reflected off a mirror?
When light is shifted 180 degrees out of phase, is it the mirror image of the light wave?
|
So I've read quite a few papers recently claiming that if you have a system with periodic boundary conditions, there are no electrical charges. I'm trying to better understand why this is the case. Basically, there are no charges on toroidal geometries. My intuition is that you can't have one electrical charge because ... |
We have a completely uniform, hollow sphere made of high-strength steel. Inside this sphere a Tsar Bomba (RDS-220) is detonated. How thick (ballpark figure) would the sphere need to be to withstand the detonation without the outer surface being breached?
Some key values that may or may not be relevant:
Blast yield: 21... |
I’m stuck on a basic introductory point regarding twistors. I understand the mapping of 4-vectors to hermitian matrices, and the incidence relation defined by pairs of spinors. And I understand that a null vector will result in the matrix having determinant zero, therefore being of rank one. Then it can be regarded as ... |
During braking, a truck has a steady deceleration of 7.0 m/s^2. A box sits
on the platform of this truck. The box begins to slide when the braking begins, and after
sliding a distance of 2.0 m (relative to the truck), it hits the front of the truck. With what
speed (relative to the truck) does the box hit? The coeffic... |
First, sorry for the low level English and physics knowledge.
Point charge. If point charge is not possible, let me use ball charge.
The ball charge is same in all directions. (Symmetric)
It's maybe metal ball with static charge.
If it is only spinning but not translating, is there change in electric field around the c... |
We know that the Lagrangian $\mathcal{L}(q,\dot{q},t)$ which is function of generalized co-ordinate, generalized velocity and time. We consider the dynamics of particle is in configuration space. But As we know that $q$ and $\dot{q}$ are independent, Why not use both $q$ and $\dot{q}$ to construct a state space? The co... |
Is a parity transformation
$$(,,) → (−,,)$$
or
$$(,,) → (−,−,−)$$
Which coordinates cancel out momentum?
$(,,)$ (clockwise directions) and $(−,,)$ (counterclockwise directions)
or
$(,,)$ and $(−,-,-)$?
|
I have recently been doing some research into the working principle of a microwave kiln, and have run into a few things that continue to confound me. The first of which being that the devices evidently focus microwaves - which supposedly have a wavelength of ~12.2cm - through a tiny hole that is often no more than 1/2"... |
So In my last Physics Exam I had one of these question which annoyed me a lot,
"Is Motion is zero but acceleration is not zero ? If no , Why not ?
I answered that it is impossible with some line of reasoning . They gave me zero marks . They gave me a example .
"Imagine there is a ball lying on the ground on earth.The b... |
In the given capacitor arrangement while finding the potential and the charge across the capacitors all the solutions say that the charge on both of the capacitors is same. However there is a battery in between the capacitors.
Can we still assume them to be in series? Or is there any other reason that the charge on bot... |
I was wondering exactly why a ray of light changes direction when moving from one optical medium to another. I need a conceptual explanation of the above statement or why the Snell's Law is valid. I found some online explanations where the ray of light is considered analogous to a group of soldiers, swimmers, etc. This... |
Interacting quantum fields (for example, electromagnetic and electron-positron) in a vacuum state (without real particles) continue to interact, or become free?
|
I was very surprised to find an apparent limitation to a FFT on a simple signal.
Let's consider a timeseries made of L=100 points, and simply composed of the sum of two sinus waves: one with a wavelength of 7 points, the other with a wavelength of 13 points (the phase or amplitude does not matter).
If you compute the F... |
In David Tong: Lectures on General Relativity in section 6.2.5 there's discussion of extremal black holes.
Metric takes the form:
$$
ds^2 = -\left(1 - \frac{GM}{r}\right)^2 dt^2 + \left(1 - \frac{GM}{r}\right)^{-2} dr^2 + r^2 d \Omega_2^2
$$
After that Tong calculate spatial distance:
After that he concluded:
Horizon... |
Say we have the standard mode expansion of the closed bosonic string in conformal gauge. We compute the angular momenta which has an integration over the co-ordinate along the string.
We get a zero-mode part which is like the 'particle' angular momenta, and then there is the contribution from the oscillatory pieces. Th... |
Kepler's third law states $C=\frac{r^3}{T^2}$, as seen from the orbits of planets around the sun. But as the earth also attracts the sun, the sun must also orbit the earth and so $c=\frac{r^3}{T'^2}$ from which we can derive $T'^2=\frac{M}{m}T^2$ or $T'=\sqrt{333000}T$ or about 577 year. If this reasoning is correct ho... |
Given a general (time-independent) system where I have some Hermitian operator $O$, is there a way of knowing if $O$ happens to be the Hamiltonian?
In other words, are there special mathematical properties that set the Hamiltonian apart from all other Hermitian operators?
(I am looking for a mathematical test, so a phy... |
Take the most simple academic example for interference. Since it is not any real experiment, one can have shocking contradictions.
For example: 2 monochromatic plane waves with (parallel) amplitudes propagating in the same direction. The Poynting vectors of the 2 waves without superposition are always constant. Once su... |
Can someone answer this question, I have chosen this from Bodendorfer's article on 'An Elementary Introduction to Loop Quantum Gravity' from section 3 General relativity in the connection formulation and quantum kinematics exercise 3.6.10
Ashtekar-Lewandowski Vaccum
A Cylindrical Function Ψ = 1, this state is called As... |
First of all, an image to describe the situation we have:
Background
A uniform disc is rolling without slipping on a flat surface. The disc itself is also in circular motion about the point $O$. I have tried this with a roll of cellotape so the situation itself seems plausible. What I want to find is the radius of t... |
Generally people says that the state $1s(1)2s(1)$ $ ^1S$ is an excited state of Helium atom . Variation theorem guaranties that the expectation value of this state is greater than the ground state, that is $E[(1s(1)2s(1)]\geq e_0$ where $e_0$ is the ground state energy.
For example since $1s(2)$ $ ^1S$ is the ground... |
We know that $\sigma_{xy}$ in the integer quantum Hall effect (or quantum anomalous Hall effect) can be calculated by the Berry curvature, but we also know that $\sigma_{xy}$ is calculated by the properties of the body!
Why it can be explained as edge state to some extent? I know edge-boundary correspondence, but what ... |
What property should a dielectric need to become an electret?
At first, I though polar dielectrics formed electrets, but non polar dielectrics like polypropylene also form electrets.
So what property do you need to become an electret?
|
So we have lots of paper for photocopy. They come in a bundle. What I have noticed is that There are sine curves or maybe cosine when I saw them from the side. That's Look like:
Is there any explanation for these curves?
|
Suppose I want to infer the configuration of a function $q(t)$ with $t \in \Omega$, where $\Omega \subset \mathbb{R}$, given a dataset $d=[\{t_1, q_1 \}, ..., \{ t_N,q_N \}]$, where $q_i \equiv q(t_i) $. Suppose further I know the dynamics of the field, for instance $q(t)$ is assumed to obey the equation of the anharmo... |
I am working on a project and i need the payload capabilities of different rockets to LEO, mars and lunar orbit. Usually the LEO payload along with all other relevant data is given for all rockets. is there any way i can calculate the other two from that?
|
Can anyone help me get a handle on how to go about solving for the energies and wave function for a particle in an infinite box where there is a step function? That is, the potential is infinite for $x<0$ and $x>a$, $0$ in the range $0<x<\frac{a}{2}$, and $V_0$ in the range $\frac{a}{2}<x<a$. This is for self-study f... |
During a discussion with a friend on the equivalence principle, the point was made that it only applies to objects in free fall, and therefore wouldn't apply to objects on an inclined plane. In other words, there would be a difference between how an object would fall on an inclined plane in a gravitational field and h... |
There are two cases when drawing FBD of a block resting on friction or frictionless surface.We draw at the back of it a force of 20N in the right direction or we draw of force of 20N in the front of the block I.e front side (Not the top side ) in the right direction.Now , I see that in case 1 there is a push force and... |
A physics professor told me that: "The QFT amplitude is always proportional to the tree-level amplitude, even for non-renormalizable theories". i.e.
\begin{equation}
\mathcal{M}^{n-loop}=\mathcal{M}^{tree}\times f(\lbrace p\rbrace)
\end{equation}
I could not find this claim in any of the QFT textbooks however. Is this ... |
A wheel is mounted vertically and a mass $m$ is placed on it. The position of the mass makes an angle with respect to the vertical axis (that is $\Theta \neq 0$ or $\neq 180$). Therefore, gravity will make the wheel and the mass start rotating (this is like a simple pendulum). My confusion is that
Is the angular moment... |
Wikipedia gives the most general expression for the $n^{\rm th}$ moment $\mu_n$ of a physical quantity $\Lambda$ as:
$$ \mu_n = \int {\bf x}^n \space \lambda({\bf x}) \space \rm d^3 x$$
provided that we know the spatial distribution density $\lambda({\bf x})$ of $\Lambda$. Here are some examples (again taken from Wikip... |
In my physics-class, I was told that,
"The melting point of the same substance changes under different pressure. But it can change in two different manner"
There are 2 different ways it can change:
$(1)$ For higher pressure , the melting point will be lower (Like water)
$(2)$ For higher pressure , the melting point wil... |
I have read this question:
Why is the sky blue and the sun yellow?
where John Rennie says:
The only light we see directly from the Sun is the light that travels in a straight line from the Sun to our eye
If you consider the upper yellow line we can't see this light ray because it misses our eye. However the Rayleigh s... |
Recently I decided to make a communication system throughout my house (electronic free) so I decided to make a system of tin-can telephones. I realized quickly that it would be difficult, though, because they don't corner well (or at all). So my first idea was to make what I called 'repeaters', and you would put one on... |
Let $\mathcal{E} \to CP(A \to B)$ (completely positive linear map) be a trace non-increasing $CP$ map.
Show that any operator sum representation $\{M_x\}_{x=1}^{m}$ of $\mathcal{E}$ satisfes $\sum_{x=1}^{m}M^{*}_xM_x \leq I^A$.
Show that the marginal of the Choi matrix $J^{AB}{\mathcal{E}}$ satisfies $J^A{\mathcal{E}}... |
here is my question:
Im trying to find the matrix elements of the momentum operator $\hat{P}$ in the position basis $|x\rangle$:
$$\langle x|\hat{P}|x'\rangle := \langle x|\hat{P}\int dp|p\rangle \langle p|x'\rangle=\langle x|\hat{P}\int dp|p\rangle \frac{1}{\sqrt {2\pi}}e^{-ipx'}$$
where $\hbar=1$. Now acting $\hat{P}... |
I've seen in a few places an argument used that when the flux is zero, the electric field is zero but I don't understand how implication is followed while I do understand that a zero electric field will generate no flux through any surface but how does zero flux imply no electric field?
As a simple counter-example, con... |
In order to derive the geodesic equation of motion from the covariant conservation of the energy-momentum tensor we have to do the following procedure:
$$ T^{\mu\nu}_{\space\space\space\space;\mu}= \partial_\mu T^{\mu\nu}+\Gamma^{\mu}_{\space\space\sigma\mu}T^{\sigma\nu}+\Gamma^{\nu}_{\space\space\sigma\mu}T^{\mu\sigma... |
I know that special relativity deals with the concept of time in a totally different way than classical (and quantum?) mechanics does. But are there some theories that treat time in another way? Are there some theories that are just about time? Or maybe extensions of special relativity (other than GR)?
My questions are... |
I want to make a pressure container out of this food container
The seal is rubber that is pushed into plastic edges.
However, I don't know if it's going to work until after i've attached an air valve to it.
My question is - at what rate is it going to pass air at an inside pressure of 2 atmospheres?
I wan't it to hold... |
The buoyant force exerted by an object in water is given by $\rho.g.v_{submerged}$
Which only depends on the volume submerged and nothing else(I think)
But can it be applied to partially submerged bodies like in the diagram below?
I feel like it can be applied to the part which is submerged, but my teacher says otherw... |
I've watched video Einstein's Relativistic Train in a Tunnel Paradox: Special Relativity and have read wiki - Ladder_paradox. My question for the case where train is trapped in the tunnel. Unfortunately (in my opinion) in the video from train view it is still train moving, though longer than the tunnel. However, from ... |
Does it only mean that if you have an $n$-component vector $\phi$, you can transform it with $A$, where $A\in U(n)$, so that you get $A\phi$, and then you can get the original vector $\phi$ back with $A^\dagger (A\phi)$?
Is this all the phrase "the complex inner product has $U(n)$ symmetry" means? Or are there other im... |
For instance, I would like to compute the entropy $S$, given that the internal energy is expressed as:
$$ E(V, T)=\sigma V T^{\frac{\alpha+1}{\alpha}} $$
I feel like there has to be a relationship between these two properties but I am unable to find it.
|
while asking for calculation of magnetic rigidity for accelerators, I am seeing notations like '238-U-28+' & '197-Au-77+
Previously I was comfortable seeing charge state like 40-Ca-1+ ions before. which would obviously mean Calcium ion with a positive charge or that has lost one electron. But here U-28+ it seems a litt... |
In Non-Relativistic Lagrangian mechanics usually we didn't impose any constraint on the Action/Lagrangian, rather than to be respectively a functional/function (or 3 form on Manifolds).
In QFT and Relativistic field theory we usually impose that the Action should be a Lorentz scalar, and the Lagrangian density a Lorent... |
There are well-known Penrose diagrams for black holes:
And for collapsing star:
Diagram for collapsing star is obtained by joining two Penrose diagrams:
Is it possible to join diagrams for two black holes?
These black holes will rotate and emit gravitational waves and after will collapse to one BH. How to join diagr... |
When I have an 0th order equation of motion of the form
$$
0=a(\phi)+\partial_a\partial^a\phi +\partial_\phi V(\phi),
$$
can I use this equation to simplify the first order equation of motion?
Sure, if the first order has a term, containing the 0th order as a factor, it gets cancelled, e.g.
$$
0 = x + y + q*(a(\phi)+\p... |
How do scientists know the min limit of temperature is -273 degree celsius?
I wonder how do scientists confirmed that there is no place belong to less than -273 degree celsius in the universe? Why the scale is exactly -273 degree celsius?
|
From the book Quantum Mechanics by Cohen-Tannoudji it seems that the only requirement for an Operator to be an Observable is to form an orthonormal basis in the state space (finite or infinite dimensional)
"By definition, the Hermitian operator $A$ is an observable if this orthonormal system of vectors forms a basis i... |
Not sure if this is a path integral. Never finished QFT, but I remember stuff like this. I have a density function like,
$$
P(z) \mathcal{D}z \propto \exp \left[ - \iint_0^T ds dt ~ \lambda(s, t) ~ z(s) z(t) \right] \mathcal{D}z
$$
and I want to get $\mathbb{E}[z(s)z(t)]$, so I was planning to get the partition functio... |
The other day in class we derived Dirac's equation and talked a little about its relativistic covariance. In particular, we said that the electronic wavefunction $\psi(x)$ transforms as $\psi'(x'(x))=R(\omega)\psi(x(x'))$, given a parameter-dependent matrix $R(\omega)=e^{\frac{i}{4}\omega_{\mu\nu}\Sigma^{\mu\nu}}$.
I h... |
How do I compute the Matsubara sum
$$\sum_n \log\left(-i\omega_n +\frac{k^2}{2m}+\mu\right)?$$
If I have sums like
$\sum_n \frac{1}{i\omega_n -m}$, I can sum it up by calculating the sum of residues of the function $\frac{1}{z-m}g(z)$ at the poles where $g(z)=\begin{cases}
\frac{\beta}{\exp (\beta z)+1} \text{ for Fe... |
In the context of transportation theory (electron and thermal conductivities), what is the physical meaning of extrinsic and intrinsic contributions to the Hall effect (i.e. transverse conductivity)?
For example, in the article "Anomalous Hall effect in the Dirac electron system with a split term", they define the Hall... |
I'm writing an essay on the history of physics from a mathematical point of view. It's divided into a handful of impactful persons/ideas, one of the largest being the works of Einstein. Immediately following Einstein is a discussion of more 'modern' work on unified theories. I'd like to include some information, as sub... |
Hi there and really sorry for bothering you!
Recently I have begin to studing GR and I have found some simulations regarding Neutron Star Mergers.
Take a look at this video for example: https://www.youtube.com/watch?v=UQCfo5L3ShQ&ab_channel=CoRe-ComputationalRelativity
If the metric is constantly changing. What exactly... |
I have started learning about rotational mechanics about a month back. I am trying to derive everything from the fundamentals.<br>
First off, I derive the relation for the moment of inertia using the Kinetic energy argument. ($I= \int_0^m r^2 dm$)
From here by analogy to linear dynamics, I state Angular momentum $\ma... |
There are many presentations of the proof of the Mermin-Wagner theorem in many different contexts (which talk about quantum vs. classical, existence of unique Gibbs measure or non-zero mean magnetization, talk about a Lie group of symmetries or just the XY model). I am aware of the relations between the various stateme... |
The torque of the disk is through its Center of mass
A coin is placed on the disk in r distance.
First when the disk has friction, the system seems like this-
If the disk don’t have any friction, would not the coin go toward the center?
|
Some days ago, the wheel in the sliding door of my house broke and thus it is creating a big noise continuously whenever I move it against the aluminium partitions. I knew and observed that friction creates this noise but I don't know the exact mechanism. So I am asking for a physical relationship. Can someone expla... |
I watched a television documentary on superconductors. The summary was that in a ring of neodymium magnets, the superconductor would spin around on top of them levitating whilst it was frozen with liquid nitrogen. Once it got too warm it would drop.
Can I assume that, provided the superconductor is kept frozen, it can ... |
I'm currently going through a book on material science, a field of which I have little background knowledge. One of the questions asks me to calculate the bond energy per molecule when given the following data
Bond energy: 7.74 kJ $\text{mol}^{-1}$
Density: 1.77 g $\text{cm}^{-3}$
Relative atomic mass: 40 g $\text{mol... |
In Sakurai's Modern Quantum Mechanics Chapter 1, he makes an analogy between polarized light and the results of the Stern-Gerlach experiment.
He compares the existence of a $S_{z}^{+}$ and $S_{z}^{-}$ component in an $S_{z}^{+}$ beam passed through an apparatus that splits the beam as $S_{x}^{+}$ and $S_{x}^{-}$ to pol... |
I am reading Schwartz' QFT book, where in chapter 20, he discusses IR divergences. At the beginning of chapter 20.1.2, he considers the sum of the following diagrams in Feynman gauge and in the limit where the electron mass is negligible:
which apparently can be written by using QED Feynman rules like this:
$$ i\mathc... |
Which factors will we consider for deciding whether a proton is easier to remove or a neutron?
Considering Coulombic forces, proton experiences repulsive force and hence easier to remove. But why will we not consider attraction from electrons?
Can we decide it without experimental data and values ?
|
For a particle detector (e.g. ionization chamber, proportional counter,...), what factor determines the polarity of the pulse of the "raw" signals (signals straight from the electrodes before going through an amplifier)?
|
We all know that the speed of light is $299792458~\textrm{m/s}$. Here we use meters as measuring sticks to measure the speed of light .
But how is a meter defined? It is defined using the speed of light. Here there is a weird circular reasoning. How can this be avoided? Do we have to accept the speed of light as $2997... |
In page 168 in Ref. [1], the authors search for a suitable order parameter for the nematic phase in liquid crystal. If $\vec v^\alpha$ is the direction of a single molecule, than due to the inversion symmetry, both $\vec v^\alpha$ and $-\vec v^\alpha$ contribute to order so the order parameter must be even in $\vec v^\... |
I have a question bothering me for a long while. It is kind of a combination of the questions and answers of two other posts:
A
B
The setting: we have a rigid body, for example a thin rod, in space. We give it a nudge at the center of mass or at one of its tips.
A explains, that in both cases the Force will change th... |
For the sake of simplicity, I am considering a 0+0d scalar field theory with multiple bosonic and fermionic fields/variables. The fields are coupled together up to a certain order (say 4) with coefficients such that the resulting Lagrangian is bosonic.
Is there a "necessary condition" for this theory to admit SUSY gene... |
We have a speaker and microphone, distance between them is 10 meters. They are both on 1 meter distance from sound-reflecting wall. Velocity of voice is 340 m/s. It is observed that microphone does not register certain voice frequencies. What is the lowest frequency that microphone does not register?
If I understood th... |
I want to solve for the state after qubit rotation by operator, $U_\alpha = e^{i\alpha\sigma_1}$ = $\begin{bmatrix} \cos\alpha& i\sin\alpha\\i\sin\alpha & \cos\alpha\end{bmatrix}$, if qubit is initially in state $\left|0\right\rangle$
Using matrix representation, I can easily solve this to get;
$ U_\alpha \left|0\right... |
We did this derivation in class. We took a cross section of an ideal solenoid and took a rectangular loop to apply ampere's circuital law. It is pretty much the same as in the diagram but the sides 'ad' and 'bc' were extended such that the loop covered the complete solenoid including the current coming 'out of page'. ... |
The term 'coherence' is frequently used in relation to certain quantum systems such as LASER, superconductors, etc. Please help me understand what we mean by the coherence of a quantum system. How do we describe it quantitatively and interpret physically? Also, why is it important/interesting?
|
Given the quantum Heisenberg model with Hamiltonian
$\hat{H}=-\frac{1}{2}\sum_{i,j}J_{ij}\hat{\textbf{S}}_{i}\cdot\hat{\textbf{S}}_{j}$,
the uniform mean-field approximation $\hat{\textbf{S}}_{i}=\langle\hat{\textbf{S}}\rangle+(\hat{\textbf{S}}_{i}-\langle\hat{\textbf{S}}\rangle)$ allows to rewrite it as
$\hat{H}_{MF}=... |
How can I make the (far field) electric field of a dipole dependent on the numerical aperture of a collection lense it is passing through?
|
Object A is located on the floor at the equator.
Is that the magnitude of the normal force on A equal to its weight?
How to obtain an expression for normal reaction in terms of $m,g,r$ and $\omega$?
|
The total partition function of N identical, independent particles is $Z^N/N!$ where Z is the partition function of a single particle. To find out the correct magnetization due to N identical atoms of magnetic moment $\mu=-g \mu_B J$, the partition function is taken to be $Z^N$. See page 4 of this note. http://physics.... |
$(a)$ Let's say A person is pushing an object. Then the object will put a force on the person equal to the force the person is putting on the object (because of Newton's third law). Then the person should move backward because of the opposing force. But clearly, the person moves in the same direction as the object whil... |
For the time-dependent Hamiltonian
$$H = \frac{\hat{P}^2}{2m} + \frac{1}{2} m\omega^2\hat{X}^2 + m\omega^2vt\hat{X} +v\hat{P}$$
I would like to calculate the ground state, more precise, the stationary point up to a moving origin. The Hamiltonian looks like a quantum mechanical oscillator but has 2 additional terms whic... |
As I have realised, most of the Uranium and Plutonium inside an Atomic Bomb do not actually fission together, even if the critical mass is used. In fact, for Little Boy, only 1.09 kg out of 64 kg of the uranium fissioned, while Fat Man only had 1 kg out of 6.19 kg of plutonium fissioned. Eventually, nuclear fusion is u... |
I know that the optical gap is generally lower than the fundamental gap, but when is the optical gap is lower than the fundamental gap?
|
In the standard canonical quantization procedure there are two rules.
Transform all quantities to operators.
Transform the Poisson bracket to a commutator.
Of course it will be nicer to minimize the number of axioms, so my question is very simple: Is there a way to derive the second rule from the first one (or the op... |
I am not a physicist and do not know anything about quantum mechanics (except that it can be formulated using Hilbert spaces), but watching a vulgarization video about Bell's paradox, I had a question that I do not know how to answer. Please excuse me if what I say is nonsensical.
In the video, Bell's paradox is formul... |
If I have a mass on a string that follows SHM and I add a constant force in the upwards y-direction to the mass, how does its period change? We assume the upwards force is less than the weight.
I had one idea, that is to sum the vertical forces, divide by g and calculate the period as for a pendulum with a mass $m_2$, ... |
In this article (here) it says that unstable particles can be represented as a stable superposition of the decay products. It says this representation is most relevant for when resonances only appear as resonances in cross-section curves, so the unstable particles are not observable (resolvable in time). It says Gamov ... |
Let's consider plane waves propagating along $z$ direction, namely wave of this form: $\vec E(ct\pm z)$,$\vec B(ct \pm z)$.
On my book there is a derivation that shows the following relations are true for such waves ($\vec C$ intensity and direction are those of the speed of light in vacuum):
$$\vec E=\vec B \times \ve... |
In the context of this page, I have more or less understood the proof and I have written a summary below:
Consider any Gaussian surface inside a large surface which contains the cavity. Flux through this surface is zero as the electric field at every point on it is zero. Therefore either zero charges enclosed or an e... |
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