0
votes
0answers
1 view

What is the difference between luminosity of a star and absolute luminosity

The equations for the habitable zone of a star call for the "absolute luminosity." Is this different from the luminosity value calculated by AσT^4 (Stefan-Boltzmann ...
0
votes
0answers
3 views

Minimal size of an optical lense

Is the minimal size of an optical lense (diameter, width and the curvature) limited by the wavelength of the incident light?
0
votes
0answers
4 views

Is it possible that an object orbits another object without ever tangenting or crossing its equator?

Imagine Object 1 beeing the earth and object 2 beeing the moon having a orbit around earth, like the yellow line is demonstrating. Could something like this anyhow naturaly as standalone occur? I'd ...
0
votes
0answers
5 views

What does “ambient atmosphere of 20 mu” mean?

I've read through a publication from 1960 which discusses oxygen annealing. It shows a the following graph. What does the "ambient atmosphere of XY mu" mean? What is a mu atmosphere? taken from: ...
4
votes
1answer
27 views

How can I tell that a Lagrangian has an $SU(2)\times SU(2)$ symmetry?

this is a very basic question and it probably has a very simple answer. I was reading through some handouts when I came over something that I did not understand. One considered the simple Lagrangian ...
0
votes
0answers
15 views

Is the Pauli exclusion principle also involved in free electrons?

Imagine I want to make a laser of electrons like a laser of light. Is that possible, or does the Pauli exclusion principle prohibit that?
1
vote
0answers
4 views

Rusting of induction hardened portion when the non hardened portion is chrome plated

When a ferritic steel component that has a portion of it induction hardened and quenched in oil is chrome plated over the non hardened portion, I see rust formation after some time on the induction ...
1
vote
0answers
10 views

Proof from Calculus 1 [migrated]

Last days, from going into a website of the university of Pisa, I found an exercise given in the previous exams, in 1999. The problem was like: Given a continuous function f in R, and which ...
-1
votes
0answers
9 views

How can I find the acceleration of a spring when the spring is elongated of $x = y$ $meters$? [on hold]

Good morning to everyone! I have a problem that I don't know how to solve: I have a block on a plain, I know its mass I know the angle of inclination of the plane, and the coefficient of friction. It ...
0
votes
0answers
12 views

ultimate tensile strength for elastomers

I'm doing experiments with an elastomer and I'd like to know how I should determine tensile strength in practice. Is this the point where I begin to observe tears in the elastomer or where the ...
3
votes
1answer
19 views

Is there a theorem which specifies the state (with energy $E$) with maximum entanglement?

Does there exist any theorem in quantum information which states that the particular state with energy $E$ is the state with maximum entanglement (or discord) among all possible state with the same ...
1
vote
0answers
21 views

Origin of the magnetic field of Earth

The Dynamo theory gives a good explanation of the magnetic field of the Earth: the Coriolis force focus inner currents into current spirals generating magnetic(s) field(s). What I'm trying to ...
0
votes
0answers
16 views

Light passing through two sets of double-slits in tandem

Has anyone ever set up a double double-slit experiment - one in which a second double-slit is inserted at one of the bright spots of the interference pattern produced by the first one? The intensity ...
-2
votes
0answers
19 views

If mass rotates at varying speed, will the whole system be pulled in the direction of the strongest centrifugal force?

And, what are the implications in terms of Newtonian law of action and reaction, as well as conservation of momentum and conservation of energy?
0
votes
0answers
7 views

What is the ray diagram for Schuster's focussing?

I haven't been able to find it online. Our course book also doesn't provide a ray diagram for this particular phenomenon. I feel like it's difficult to understand the process without the ray diagram.
1
vote
0answers
8 views

What is signifcance of density of the universe if it changes?

So theories of expansion of the universe (before dark matter and energy) said that the ultimate fate of the universe is based on the density of the universe and this being compared to the critical ...
0
votes
0answers
3 views

what is the benefit from finding relative speed/ velocity of two moving objects (cars)in the same direction?

I just want to know why do we find relative speed/ velocity of two moving objects (cars)in the same direction? I mean how will this give me benefits.
1
vote
3answers
252 views

Is it possible to get a photon with -1 spin?

Wikipedia just mentions,a photon have a spin of value 1. But I want to know, is there 2 possible spins for photon? i.e. +1 and -1? (like electrons, that can have +1/2 or -1/2 )? or not? If spin-...
0
votes
0answers
7 views

Rotating rod viewed in standard frames S and S'

I am doing a problem in relativity book by Rindler and for one question I do not have the answer. It states that in the rest frame a rod centred on the origin rotates uniformly (frame S'). What will ...
0
votes
1answer
11 views

What does the removed heat from air and water due to the evaporation depends on?

If we have an evaporation process, what is the proportion of heat removed from the air and water? Does it depend on the isobaric specific heat capacity, therefore if the water has the heat capacity ...
0
votes
0answers
12 views

the lagrangian of the axial vector field

What is the Lagrangian of a axial vector field? How can I find it? I want to describe a model which is made by standard model with extended by an axial vector and a Dirac fermion!
0
votes
0answers
13 views

Charge distribution in a conductor

If some charge is given to a hollow conducting hemisphere of some thickness,where will be the charge present in that hollow conducting hemisphere?
-1
votes
0answers
20 views

Laws of motion in use

Do the laws of motion apply to photons and other particles like mesons,gluons etc.Can you please specify the reason if yes and no
0
votes
0answers
14 views

Can DC electric field be regarded as a quantum harmonic oscillator? [duplicate]

The essence of quantum theory of the radiation field is the association of a quantum harmonic oscillator with each mode of the field. However, in the case of DC electric field, can we describe DC ...
10
votes
1answer
283 views

In quantum mechanics, how exactly do we associate Hermitian operators to classical observables?

In a first course on quantum mechanics, everybody learns some version of the following statement: Postulate: To every classical observable $A$ of a physical system, there corresponds a Hermitian ...
0
votes
0answers
8 views

Is the reduction of tensor loop integrals to scalar integrals using Passarino Veltman Functions, theory dependent?

While reducing the tensor integrals to scalar integrals all that we use are Lorentz covariance and the physical interpretation of the result. Thus I think that the Pa Ve Reduction of Tensor integrals ...
-2
votes
0answers
30 views

Contradictory kinematics formula [duplicate]

The displacement of a particle in the $t$th second of its motion is given by: $$ S(t)=u + \frac{a}{2}\left(2t-1\right) $$ where $u$ is the initial velocity, $a$ is the acceleration and $s$ is the ...
0
votes
0answers
32 views

Publishing in American Journal of Physics [on hold]

Can I publish my article in American Journal of Physics, if I am not a part of any educational/research institute nor a part of private industry? Also I do not have any referee. Do I need to pay to Am....
1
vote
2answers
34 views

Second Law of Dynamics and Pulleys

The system in the figure is initially at rest . If the system starts to move , evaluate the acceleration of the block $A$. Mass of the block $A$ is $m_A = 60\;\mathrm{kg}$ ; mass of blocks $B$ and $C$ ...
-4
votes
1answer
32 views

Newton's 1st law

If all of a sudden the gravitational force and gravity disappears then the planets would still continue to rotate and revolve ? Give reason
0
votes
0answers
11 views

Selection rules for electric quadrupole radiation

The selection rules for electric quadrupole radiation in a Hydrogen-like atom are: $$ \begin{aligned} \Delta l &= 0,\pm2 \hspace{1cm}(l=0\leftrightarrow l'=0 \textrm{ is forbidden}) \\ \Delta m &...
0
votes
1answer
20 views

What is the meaning of a negative Galactic longitude?

What is the meaning of negative longitude in Galactic coordinate system? Does the longitude $-65^\circ$ equal $295^\circ$?
3
votes
1answer
25 views

Can circular polarized light be cancelled?

I can cancel the light output from an LED screen by placing a linear polarizer at 90 degrees from the linear polarizer built into the LED display. OLED displays use circular polarizers instead of ...
0
votes
1answer
10 views

Reducing coefficient of friction by vibrations?

Very simply put, if one places a block of some material on a level surface and pushes it horizontally, a certain coefficient of friction is measured. If one tightly couples an oscillator of some sort ...
2
votes
1answer
60 views

Does the use of $\gamma=\left(1-v^{2}/c^{2}\right)^{-1/2}$ automatically assume a (+ - - - ) metric?

In Special Relativity, does the use of $\gamma=\left(1-v^{2}/c^{2}\right)^{-1/2}$ automatically assume a (+ - - - ) metric convention? For introductory textbooks, the Lorentz factor is is always ...
0
votes
1answer
34 views

Before Dark Energy was discovered

I'm really confused on this topic. Pardon my French if my questions seem really stupid. Before Dark Energy was discovered in 1998 did scientists know that the cosmological constant calculated, I ...
2
votes
0answers
11 views

Does the vacuum have a zero Seebeck coefficient?

I was considering how at very high energies (e.g the Schwinger Limit) the vacuum starts having properties we would normally associate with "materials", such as non-linear polarizibility. The Seebeck ...
-6
votes
0answers
17 views

Answer true or false? [on hold]

True or false? Q: The magnitude of displacement is equal to distance covered in a given interval of time if the particle ___. A: moves with constant acceleration
0
votes
0answers
39 views

Why do we add gamma to derive the Lorentz transformation?

I was trying to derive the Lorentz transformation with the following... $$\frac{t'}{t} = \frac{c-v}{c},\qquad \frac{t}{t'} = \frac{c+v}{c}$$ After adding gamma $$\frac{t'}{t} = \gamma\frac{c-v}{c},\...
-1
votes
1answer
21 views

Curious about headphones

So I'm trying to learn more about headphones. I have a small piston that is in a small sealed volume (the earcup, say it is $25\, cc$). And there is a front volume between the piston and the ear (...
1
vote
1answer
39 views

Differential equation in RL-circuit

I am self-studying electromagnetism right now (by reading University Physics 13th edition) and for some reason I always want to understand things in a crystalclear way and in depth. Now look at this ...
0
votes
0answers
29 views

Double Atwood machine alternate solution is wrong?

** NOTE I cannot post multiple links due to reputation so here is my reference link.** I came across a double atwood machine problem where we were to find the acceleration of each mass(image in link)....
0
votes
1answer
22 views

Dyson Sphere Structures [on hold]

In a type II civilization we may need to harvest the energy of neighboring stars. Freeman Dyson gave an interesting point of view that we could invent a megastructure to harvest this type of energy. ...
-3
votes
0answers
64 views

What does the Free Will Theorem Imply?

Sorry if discussion of the Free Will Theorem belongs in the philosophy section, but as it is in the realm of physics too, I thought I would post it here instead... If we have a free will in the ...
0
votes
1answer
28 views

Time reversal symmetry for non-orientable manifold

From a recent paper by Kapustin(https://arxiv.org/abs/1406.7329), he argued that for non-orientable manifold with spin structure $Pin^{\pm}$, the corresponding time reversal symmetry $T$ squares to ${...
0
votes
2answers
50 views

How do we determine the location of particles?

Can someone explain how the location of a particle is determined both theoretically and experimentally (if possible)? Can the location of a particle be given by the uncertainty principle? (dividing ...
-1
votes
0answers
23 views

Why does a charged parallel-plate capacitor with infinitely large area on both plates never discharge? [on hold]

Alternatively, as the distance between the plates in a charged capacitor approaches zero, Coulomb force becomes greater and greater. How can it be discharged if there's such strong attraction? Both ...
0
votes
0answers
35 views

Work done by the battery in series with capacitor with changing dielectric

If we have a battery with voltage $V$ connected in series with a parallel-plate capacitor of capacitance $C$ with dielectric $\epsilon$,and then we pull the dielectric out, the infinitesimal work done ...
0
votes
0answers
25 views

Why must the Vacuum Manifold contain the quotient group?

For a symmetry breaking pattern $G \rightarrow H$, the vacuum manifold must contain the quotient space $G/H$. In most cases, we take the vacuum manifold to be the quotient space. My question is, Is ...
3
votes
1answer
40 views

Can Light Waves Be Irregular?

From what I understand, electromagnetic radiation produced by an antenna is of the frequency that corresponds to the motion of the electrons moving around in the antenna. And I assume that the ...

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