0
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0answers
4 views

Causal networks and “local” entanglement

On his Opus Maximus, a new kind of Science, Stephen Wolfram suggests that causal networks can create behaviour similar to entanglement because the local structure of space is only an averaged ...
1
vote
0answers
3 views

How much of water's surface tension is entropic?

Water molecules on the surface of an air-water interface have preferred orientations that lower their energy. This implies that these molecules are not uniformly distributed in orientation space, ...
0
votes
0answers
4 views

What are the dynamics of the “break the surface tension with a drop of soap” experiment?

There's a common experiment exemplified in the first few seconds of this video: https://www.youtube.com/watch?v=WsksFbFZeeU You put some food coloring in the center of a plate of milk, then put a ...
1
vote
1answer
9 views

Why does Bernoulli's equation only apply to flow along a streamline that is in viscid, incompressible, steady, irrotaional?

I am learning about hydrofoil on this website. In a later video I watched, I learned that in the process of deriving Bernoulli's equation, $constant=P/d+gh+1/2v^2$ has to multiplied through by ...
0
votes
0answers
6 views

Are neutrinos affected by electromagnetic forces?

I know they don't interact with matter nor any electromagnetic forces, but I know they have mass, very little mass but they have. When something has mass it must be attracted by gravity and other ...
1
vote
2answers
12 views

Does Unitary operator take a pure state to a pure state or can it take a pure state to a mixed state?

Does Unitary operator take a pure state to a pure state or can it take a pure state to a mixed state? I think so but why? I assume the Unitary operator acts on a pure state only.
0
votes
2answers
7 views

Why does electromagnetic induction creates both voltage and current but static electricity only creates voltage and no current?

Why is it that electrons do not move the same way in triboelectric as in magnetic induction when both creates voltage? Triboelectricity can even create tens of thousands of volts like Van De Graf ...
1
vote
0answers
9 views

When does $E=\frac{3}{2}pV$ hold?

I only know that it holds for classical (monatomic) ideal gas and quantum ideal gas. But does it hold for interacting classical gas (e.g. van der Waals gas)?
0
votes
0answers
19 views

Wavefunction of electron in infinite well with non-zero potential

Consider an electron moving in a potential $V$ defined by $$V(x,y,z) = \left \{ \begin{array}{ll} \alpha(x^2 + y^2) & 0 \leq z \leq a \\ \infty & \text{otherwise} \end{array} \right. $$ How ...
0
votes
2answers
11 views

How do I draw the force field lines of an isotropic oscillator?

In general, how do I draw the force field lines (in the sense of Faraday) of a central force field growing with distance? As a particular example, how do I draw the force field lines of an isotropic ...
0
votes
1answer
17 views

Very Basic Circular motion question

I was asked to draw a diagram of the forces acting on a ball in vertical circular motion when it is at a horizontal point. I drew the weight of the ball acting straight down and the centripetal force ...
0
votes
0answers
12 views

Transformation law for the eigenfunction representation of dilations (scale transformations) in CFT

On page 32 section 2.1.2. of http://arxiv.org/abs/hep-th/9905111 a representation $\phi(x)$ for the conformal group is chosen such that $D\phi(x) = -i \Delta\phi(x) $. After that it is stated that ...
0
votes
0answers
9 views

Why is the velocity of fluid on top a hydrofoil higher than that on the bottom? What keeps enlarging the difference in these 2 velocities?

I am trying to learn how hydrofoil works. A big part of it is Bernoulli's principles. I found this article on MIT website. There are two explanation for how it works: The conservation of linear ...
1
vote
0answers
5 views

Ionospheric electron density measurements

I've been working on measuring total electron column density (TEC) with multi frequency GPS data. In theory, signal delay caused by TEC differences should affect the code and carrier nearly evenly in ...
2
votes
1answer
50 views

How much Gravity is required to stop time?

Clocks free of gravitational influence run faster than those experiencing gravity. Is it possible for gravitational influence to bring time to a stop? Additionally can acceleration affect clocks in ...
2
votes
1answer
38 views

Mathematical Formulation of Classical Spacetime

I have seen two formulations of Classical Mechanics: Newtonian spacetime (learned it from the lectures of Professor Frederic P. Schuller): Definition: A Newtonian spacetime is a quintuple $(M, ...
-1
votes
1answer
25 views

Can electric heat pumps be more efficient than electric coil heaters

I have been reading about the heat pumps/air conditioners on the web. I found this article which seems to be telling something which looks like clear violation of laws of thermodynamics. The article ...
2
votes
0answers
40 views

What is the $10$ in the $\mathbf{4}\otimes\mathbf{4}$ tensor product of $SO(6)$?

This is the question 22.D in Howard Georgi's Lie Algebras book, I thought about for a minute, but couldn't come up with a plausible answer. It's a fact that the SO(6) and SU(4) algebras are ...
0
votes
0answers
31 views

What´s the origin of the four rays that come out of the reflection of candlelight in our TV?

The reflection of a candlelight in our TV shows four emerging rays. The rays vary spacial and periodical and have a repeating pattern of the colours of the rainbow. What could be the origin of this ...
0
votes
1answer
43 views

Definition of the S-matrix

when I think about scattering process I reach to slightly another definition to the S-matrix. because I understand my reasoning I hope someone could refine it to a correct one so that I can have a ...
1
vote
0answers
28 views

Definition for a trajectory in phase-space

When we say "a trajectory in phase space", when the parameter is time, do we mean the set of points in phase-space corresponding to a continuous segment in time? Does it have to be continuous? Does it ...
1
vote
0answers
30 views

Thermodynamics: Apartment Airflow: What Am I doing wrong air

Our apartment is a sauna. But sometimes it's much much hotter inside the apartment than it should be (night time it's 68 degrees outside but thermometer still says 90 inside!). I have 2 fans, one ...
0
votes
1answer
49 views

Schroedinger and Klein-Gordon equation and their complex conjugate

Let's consider the Schroedinger equation \begin{equation} i\hbar\frac{\partial}{\partial t}\psi=-\frac{\hbar}{2m}\nabla^2\psi \end{equation} If I have a wavefunction $\psi$ as a solution, then its ...
-2
votes
0answers
22 views

Please read the problem below,the approach and explain where it's wrong and what's the true concept behind?

Where should (A B C or D) charge $Q$ be placed so that the flux of electric field through the hemisphere remain unchanged? there is a charge $q$ at the center of hemisphere's base. Here's the ...
0
votes
0answers
9 views

How to calculate light transmission in dBm if it goes through SMF to MMF or MMF to SMF?

The question might be very basic, but I could not conclude it after thinking and searching about a couple of hours. If a light in fiber optics is launched in an SMF, therefore, it is connected to an ...
0
votes
1answer
40 views

Communication in higher dimensions

I'm writing a science fiction story that deals with extremely advanced civilizations. It is important to me to keep their technology within the realm of the plausible, based on our current ...
0
votes
0answers
26 views

Density matrix and basis

Given an hermitian operator $\hat{A}$ I can span the Hilbert space in terms of the eigenvectors $\lvert a_i\rangle$. For example in a spin $1/2$ system I can choose to work in a basis from the ...
-2
votes
0answers
16 views

Why are cirrus cloud those that contribute the most to climate forcing?

I read everywhere that most of the forcing produced by clouds is done by cirrus but I can't figure out why. It's obviously related to their IR absorption - emission...
2
votes
0answers
13 views

Predict liquid film thickness outside a cylinder, under the influence of a) external gas flow and b) heating of the cylinder

I tried to post this question on Computational Science SE, but I was really unsure about the most appropriate SE site. The question didn't attract a lot of attention, and since Physics SE was my ...
0
votes
1answer
40 views

Bloch sphere representation of $\sigma_x$ operator on $|1\rangle$

I am trying to visualize a Hamiltonian H=$\hat{\sigma_x}$ $$ \hat{\sigma}_{x} = \left( \begin{array}{cc} 0 & 1 \\ 1 & 0 \end{array} \right) $$ acting on the state $| 1 \rangle$. I can write ...
0
votes
1answer
27 views

EFE and Local Minkowski

Suppose we view the Einstein Field Equations (EFE) in the context of a boundary value problem with a given stress-energy tensor and boundary conditions. The problem is solved by finding a metric. Is ...
-2
votes
0answers
20 views

Book on thermodynamics for International Physics Olympiad? [duplicate]

I'm a junior in high school studying for the IPhO and I've started learning thermodynamics as part of my preparation. I have a guide to the exam that says things like this will be tested: Carnot ...
-2
votes
0answers
43 views

Is it possible for humans to jump from such an height and still be fine? [on hold]

This is the game Assassin's Creed Syndicate and here's a video showing how Evie Frye jumped from the Big Ben into a haystack - https://www.youtube.com/watch?v=JfCQe7Lqe60 Those who do not want to ...
1
vote
0answers
14 views

What shape does magnetic dust take under the influence of its own magnetic field?

Recently, I came across some very powerful neodymium magnets (the flat cylinder kind), and I accidentally broke one by snapping two of them together quickly. What I noticed is that the two halves ...
-1
votes
2answers
19 views

Electricity and electric fields equations

Whats the difference or relationship of $q$ between the equations $E=F/q$, $v=W/Q$ and $Q =ne$ ?
0
votes
0answers
38 views

Sum rule and dense limit

Is the finite size of lattice constant important for derivation of sum rules, for example, the sum rule for diagonal conductivity $\sigma_{xx}$: $$ \int \limits_{-\infty}^{\infty} ...
-2
votes
0answers
15 views

Gas thermodynamics: Kinetic energy change

Think you have a rotating pipe and air at high pressure wants to flow from outer radius to inner radius close to the roation center: question is here: Which of the following statement are correct and ...
-1
votes
0answers
11 views

Warm and Hot dark matter density profiles

for Cold dark matter, density profiles are well known and easy to find information about - NFW,Burkert,Einasto, and others. but for some reason i couldn't find explicit expressions for the density ...
1
vote
1answer
24 views

p-cycles and Fluxes

I would like to ask why the existence of a non-trivial p-cycle leads to a non-trivial flux. I would say that e.g. for a five-form $F_{(5)}$ field strength , the flux is: ...
0
votes
0answers
12 views

Copper density modification

Can you increase the density of a material surface (metal) by surface treatment? For example commercial copper. If we take the ordinary OF copper (99.95%), I would expect not to have the tabulated ...
0
votes
0answers
15 views

How can I calculate the time domain correlation function in the frequency domain?

I have an operator $a(t)$, its correlation function is: $$<a(t)a^{\dagger}(t^{\prime})>=\delta(t-t^{\prime})$$ Now I need to find the correlation function in the frequency domain. i.e. to ...
0
votes
2answers
34 views

What does J cm-1 stand?

For an optical component, I got following number as an optical damage threshold from the company, damage threshold = 10 Jcm-1,20ns, 20Hz It looks like 20ns is ...
1
vote
3answers
38 views

Equations of motion derivation doubt

I just started on learning how to derive the equations of motion using calculus. This is my first time and I have a basic doubt. So $v = \large{\frac{dx}{dt}}$ Then, $dx = v dt $ What does this ...
-1
votes
2answers
49 views

Is it possible that there are stars working on fission?

Most/all stars are getting their energy from fusion of small atoms like our sun. But is it possible according to the laws of physics that there are stars getting their energy from fission fe with ...
1
vote
0answers
16 views

What is the Single Mode Approximation?

When Girvin and co-workers solved the excited collective modes called magneto-rotons in Fractional Quantum Hall liquids, they used something called the Single Mode Approximation (SMA). My question is: ...
2
votes
0answers
29 views

Can the efficiency of a thermodynamic cycle be worked out from a pV diagram?

Is it true that a pV diagram of a thermodynamic cycle with a specified scale on both axes is enough to calculate its efficiency (such as the one below)? Is it the area within the shape divided by the ...
0
votes
0answers
23 views

Are there explicit formulas for the eigenvalues and eigenvectors of a generic 4x4 density matrix? [migrated]

I have a 4x4 density matrix all of whose elements are nonzero. Its form is $$\begin{pmatrix} a & b & c & d \\ b^* & e & f & g \\ c^* & f^* & h & j \\ ...
3
votes
1answer
35 views

$W^{++}$ / $W^{--}$ Bosons in theory and experiment

I wonder whether there is any theoretical interest in and/or experimental search for double charged bosons, probably to be called $W^{++}$ and $W^{--}$. The latter would obviously turn an electron ...
-3
votes
3answers
39 views

Electric field $E$ due to a dipole moment

Why is the formula of $$E = kp/z^3~ ?$$ Why is it $z^3$ ? I want a physics answer not math please.
1
vote
0answers
47 views

Are tides just very very very weak spaghettification?

I was wondering as to why there are two tidal bulges instead of just one on Earth, and then I saw this diagram: The oval shape that the Earth's water is transformed into in this image reminded me of ...

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