0
votes
0answers
4 views

Antiunitary operators in the tenfold way

In the classification of free fermion systems in condensed matter, physicists usually divide the systems into ten symmetry classes, first discovered by Altland and Zirnbauer. In their classification, ...
1
vote
1answer
10 views

Does visible light heat things up?

During a sunny day the walls of my house warm up (no surprise). My question: how much of this warming up (if any) comes from visible light? I associate infrared with thermal energy. If my house was ...
-2
votes
0answers
8 views

Where can a particle be found in a wavefunction

Consider the wavefunction of a particle moving along the x-axis. The probability of it being found "in a particular location" is given by the square of the amplitude of the wave at locations along the ...
0
votes
0answers
14 views

Surface brightness

I have to compute the surface brightness as a function of the radius from the following set of data: {right ascension ($\alpha$), declination ($\delta$), magnitude (m)}. I also know the center of the ...
-3
votes
0answers
23 views

The Sun's space-time warp

Can we infer that the skin of the Sun is (to some depth) blanketed by the space-time warp created by its own mass? Does the Earth's mass create any measure of a space-time warp?
0
votes
0answers
11 views

Charge Magnitude Based on Isoline Spacing

Suppose we have two positive charges of unknown magnitudes. We are given the isoline map (the equipotential lines) for the two-charge system. One has isolines more "squashed together" (more closely ...
0
votes
0answers
13 views

Wire with current in magnetic field $\vec{B}$has force $\vec{F_1}$. When rotated, $\vec{F_2}$. Find $B$

I have the following question: In a wire with $10cm$ there is a current $4A$ going 'upwards' in the $z$ axis. The force over this field, under a constant magnetic field $\vec{B}$ is $F = -0.2\vec{i} ...
-1
votes
0answers
10 views

Question about Bubble chamber reactions [on hold]

The bubble chamber pic of event which was exposed to a K- beam in a liquid hydrogen bubble chamber. So, the target consists of protons.
3
votes
1answer
28 views

Why is the Virial Theorem not a Special Case of the Ergodic Theorem? What is their Relationship?

The virial theorem involves the time-averages of the potential and kinetic energies if the motion of the system is bounded to a finite region of space. An ergodic theorem relates the time and space ...
2
votes
0answers
14 views

Why would oscillation of a gas column inhibit rather than promote mixing?

Many years ago I helped to support an experiment conducted in Japan which investigated the effects of high frequency oscillation ventilation (HFOV) on the mixing and distribution of gas into the ...
2
votes
0answers
53 views

Why are there only 3 Additive Integrals of Motion?

1. I was reading Landau & Lifschitz's book on Mechanics, and came across this sentence on p.19: "There are no other additive integrals of the motion. Thus every closed system has seven such ...
2
votes
0answers
13 views

Equivariance Relation - Superconformal Hypermultiplets

I'm concerned with equation 2.24 of http://arxiv.org/abs/1601.00482 The superconformal hypermultiplets in this paper have a conic hyperkahler target manifold and the authors want to gauge some ...
1
vote
0answers
21 views

Moment of inertia of 4 particle system

Four particles are connected by rigid rods of negligible mass. The origin is at the center of the rectangle. The system rotates in the $xy$ plane about the z axis with an angular speed of $6$ rad/s. ...
0
votes
0answers
26 views

Intuitively, why does pixel density = the diagonal of the screen?

Per this website, by the Pythagorean Theorem, $\text{Diagonal Resolution in Pixels} = \sqrt{(\text{Height Resolution in Pixels})^2 + (\text{Width Resolution in Pixels})^2} \tag{1}$ So $PPI = ...
1
vote
0answers
16 views

Reversibility of uniqueness theorem

If we use uniqueness theorem then we know that if the boundary conditions and the charge distribution is same in 2 setups in a certain region then the electric field and potential in that region in ...
0
votes
0answers
37 views

How does electron makes transition from one state to another?

i am not asking why it makes. i am curious about how it makes the transition. Does it go from one state to another via straight line or it makes smaller and smaller orbits till it reaches the next ...
1
vote
1answer
29 views

Magnetic monopoles gauge theories

I'm quoting 't Hooft: "[...] Locally stable field configurations may exist that have some topological twist in them [...].Careful analysis of the existing Lie groups and the way they may be ...
0
votes
0answers
24 views

Can these two systems be equal?

Suppose that there are two differents systems, $A$ and $B$, both associated with the same potential $V(x)$ (take, for instance, an infinite well). Then would the eigenstates of $A$ be the same as the ...
0
votes
1answer
30 views

Transformation of $| JM\rangle$ under the group of rotations

I am following the Quantum Mechanics I, Galindo A., Pascual P. and in page 207 explaining the matrix representations of the Rotation Operators in the angular momentum it appears the next (obvious) ...
0
votes
0answers
11 views

Temperature needed during the fabrication of clay products

Which type of clay, structural clay or whitewares, requires a relatively higher temperature during fabrication? I believe that whitewares requires a higher temperature, because the whiteware ceramics ...
-5
votes
1answer
40 views

Gravity vs Vacuum: what's the difference? [on hold]

It is taught that there is no gravity in a vacuum. However, there is no where in the observable Universe where there is perfect vacuum. Vacuum is SUCTION POWER...and all energies (powers) need A ...
0
votes
2answers
23 views

Perpendicular Distance for Moments

My question is: Is perpendicular distance in the equation $\tau=Fd$ the distance of the yellow or red line? My belief was that it was the red line, however when I take moments about $O$ I get ...
0
votes
0answers
26 views

Are quadrilinear weak boson couplings possible?

$ZZ\rightarrow ZZ$, $ZZ\rightarrow W^+ W^-$, etc. Are these interactions possible?
1
vote
1answer
28 views

Is there any electric current in a continuous medium of moving charges?

Suppose that unlike in real life where charge is carried in fixed discrete chunks like electrons that one has a continuous fluid in a bottle that carries charges. Suppose that the fluid is stirred in ...
0
votes
1answer
19 views

Two rising bubbles of differing temperatures

Consider two bubbles rising through some medium (water, for example). Given that the two bubbles have the same initial size, pressure, and temperature but differing velocities, which bubble will be ...
1
vote
0answers
16 views

Density of states from the Retarded Green's function for a rotating black hole

I have been studying the scattering of a scalar field around a rotating black hole in the near-horizon extremal limit. The radial solution provides the retarded Green's function, just by taking the ...
-4
votes
1answer
44 views

Area as a Vector [on hold]

Why can we take area as a vector? And say if we take it as a vector why not on the plane why only perpendicular? I clearly don't get this. What is positive or negative area or what the area has ...
5
votes
2answers
1k views

If we threw a baseball from the ISS, could we deorbit the ball?

Clearly this is a hypothetical question. Say we bring a star baseball player into NASA, prep them appropriately for a mission in space, and fly them up to the International Space Station. They go on ...
0
votes
2answers
14 views

Refraction of Sound Waves

When sound waves go from air to water what will happen to the wavelength and the angle of refraction? I used the approach that we apply to light waves and concluded the wavelength will decrease and ...
4
votes
4answers
1k views

Am I just some energy traveled at light speed?

I don't quite understand $E=mc^2$ very well, and here is my question: does this equation mean masses are just condensed energy? And does this mean that the extra energy an object has when ...
0
votes
0answers
21 views

Feynman Diagram of $\nu_\mu + p \rightarrow \nu_\mu + p + \pi^0$

According to my class notes, the following interaction is possible $$\nu_\mu + p \rightarrow \nu_\mu + p + \pi^0$$ I tried drawing a Feynman diagram and got the below, but don't know what happens ...
-1
votes
0answers
11 views

Springs and Cantilevers - how linear and repeatable are they under deformation?

I know you guys only deal with the ideal, but in practice how linear and repeatable is the response of a spring or cantilever when deformed under a test mass?
-2
votes
0answers
12 views

Why do we use a vector space for gluons? [on hold]

One gluon state cannot be added to another since qcd heavily violates superposition. Why do we still use vector spaces to describe them?
-1
votes
0answers
12 views

why is it so successful to start of with a pair potential before quantizing [on hold]

As soon as we use the quantum theory all orders of correlation functions start to appear if we move from one scale to another. Why was it so successful to start of with a simple pair potential in the ...
-2
votes
0answers
24 views

What is the difference and/or similarity between multiple universes in inflation and in quantumphysics?

Some theories propose that there are more universes. In one of them it is said that there are parallel universes, due to inflations after the big bang that created them. But in the two-slit ...
0
votes
1answer
47 views

Einsteins theory of relativity and formula of kinetic energy [duplicate]

After seeing both Einstein's theory of relativity ($E=mc^2$) and the formula of kinetic energy (K.E=$\frac{mv^2}{2}$), I noticed that that they are mostly the same, with the only difference that ...
0
votes
0answers
7 views

Conversion from PPBV to PPBM

What is the conversion between PPBV and PPBM (parts per billion by volume to parts per billion-meter)? Can I simply integrate a curve of PPBV to get PPBM?
0
votes
1answer
15 views

Can pressure be subtracted from pressure gradient

I just want to know if the pressure can be subtracted from pressure gradient. I did a google search and it didn't help me. I know the question is silly and the answer to it should be no but at one ...
-1
votes
0answers
12 views

Ibm quantum computer references [on hold]

Can someone point me towards technical discussions or papers on IBM's new quantum computer? Is it similar to the D-wave?
0
votes
0answers
5 views

How to calculate counting rate of two detectors in quantum eraser experiment?

How to calculate the counting rate between two detectors? In their paper this one , they use Glauber Formula. But I don't know this formula and can't find this formula online.
-1
votes
0answers
12 views

How to Find equations of motion and the Noether current for Lagrange symmetry group given the Lagrangian? [on hold]

photo of the problem instead of writing it here just because I don't know how to write equations here, sorry.
0
votes
1answer
25 views

The true dimension of Dirac field

In natural units with $\hbar=1$ and $c=1$, as we know, the energy dimension of the Dirac field $\psi(x)$ in QED is $\frac{3}{2}$. But in cgs units, what is the true dimension of the Dirac field ...
0
votes
1answer
12 views

Conductors, charges and method of images; Intuition?

Two charges e and -e are placed at distances d and 3d, respectively, above an infinite conducting plane (directly above one another). Find the force on the charge e. To Solve this I consider another ...
1
vote
1answer
53 views

Hamilton's equations of motion on Dirac's formalism

I'm having several doubts about the procedure proposed by the Dirac-Bergmann algorithm in order to get the correct equations of motion of electrodynamics (Maxwell's equations). Suppose I've already ...
0
votes
0answers
32 views

Velocity of (un)rolling toilet paper

Consider a roll of toilet paper. It consists of an inner cardboard core of radius $r_1 = 2cm$ wrapped in 5m of paper so the external radius is $r_2 = 3cm$. The paper is unrolled by holding on to the ...
-1
votes
0answers
23 views

How much part of an iceberg sinks in water? [on hold]

How much part of iceberg of water sinks in water. Well I know the answer is 92%, I want anyone to prove it for my homework. (water is not salty and is at 4 degree celsius)
0
votes
1answer
17 views

How do you calculate the change in location of the focal point by rotating the lense?

Image you have a lens with a certain focal length. Light will be focused into the focal plane on the Optical Axis if the light is a collimated beam which travels parallel to the Optical Axis. But I ...
0
votes
0answers
12 views

Difference between PIN photodiode and silicon surface barrier in beta spectography

In a physics undergraduate lab we performed an experiment in spectography of beta decay. We used two detectors to measure the energy spectrum of Bi207: PIN photodiode Silicon surface barrier ...
-2
votes
1answer
24 views

Is drift velocity related to diameter of conductor? [on hold]

Please help me out of the confusion regarding relation of drift velocity of electrons with dimensions of conductor .
2
votes
0answers
35 views

Is the helicity of photon Lorentz invariant?

If the helicity of a photon is $+1$ in an inertial frame, then is the helicity of this photon $+1$ in another inertial frame? The helicity operator is $$ h=\mathbf{S}\cdot\hat{\mathbf{p}} $$ with $$ ...

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