0
votes
1answer
94 views

Do paradoxes exist due to velocity addition?

Do paradoxes exist due to velocity addition ? .. In the above diagram, we have a very lengthy 259,627.885 km long space station. Rocket "A" is parked at the left end of the space station. Let us ...
0
votes
2answers
35 views

Would an airtight box filled with air act the same way to 1 bar of water pressure as the same box vacuum-sealed at atmospheric pressure?

Pressure On average, a column of air one square centimeter in cross-section, measured from sea level to the top of the atmosphere, has a mass of about 1.03 kg and weight of about 10.1 N (2.28 lbf) ...
1
vote
0answers
44 views

Proving a relation for representations of gauge groups [on hold]

I have asked this question in Math Stackexchange as well. However, given that it is closely related to gauge theories studied by physicists who will probably be more familiar with the language and ...
2
votes
1answer
43 views

Non-polarised light

We know the beam of light oscillates in electric field and magnetic field, both perpendicular to both the wave of propagation and each other. What does, however, a non-polarised beam of light look ...
2
votes
0answers
22 views

Positivity of Bulk modulus and shear modulus in isotropic materials

I have been searching through many resources, but could not find a proper thermodynamic reasoning for why bulk and shear moduli for isotropic materials should be positive. Some resources like eFunda ...
2
votes
2answers
813 views

Can polarized light be unpolarized again?

I was just wondering if there could be a process that could unpolarize polarazied light. Is that possible?
0
votes
1answer
73 views

Ball flying towards me - Newton's third law is violated?

I was trying to answer the question of the flying ball here on the basis of Newtons third law and Momentum conservation. Here is what I have tried. Lets take $m_1$ (the ball) hits $m_2$ (the man). ...
1
vote
1answer
58 views

Does rain jam radio signal?

I have experienced several times that heavy rain seems to jam the signal a radio of a bus receives. The only explanation I have is that the rain drops also become weak emitters, if a radio wave hits ...
2
votes
1answer
24 views

Why is radiance measured normal to the beam?

Radiance is defined as: $L=\frac{d \Phi}{\mathop{d \omega} \mathop{d A} \mathop{\cos\theta}}.$ I’m wondering why there is a $\cos \theta$ factor in the denominator of the radiance ($\theta$ is the ...
-1
votes
3answers
123 views

Why is every particle a sphere?

I was wondering why is everything in this universe, I mean atoms and well quarks and photons and what not some form of sphere. Is there any exploitation to the sphere being perfect and only thing for ...
1
vote
4answers
43 views

How can a 360 Degree Rainbow be formed? [duplicate]

Just a while ago while I was reading news paper, I saw an amazing article. Someone had caught a photo of a 360 Degree Rainbow. But how is it possible. I mean after refraction the only rainbows that ...
-2
votes
1answer
56 views

The Big Bang theory [duplicate]

According to big bang theory the whole universe was formed by this big explosion and it gets bigger and bigger Does that mean it has limits? and what do you think we can found beyond all that ?
4
votes
0answers
80 views

Can a discoverer give the name he wants to his finding? [migrated]

Let's assume that some scientist discovers a phenomenon that has never been noticed before. He wants to write a paper about it but he doesn't want to constantly write "effect of change of some ...
0
votes
0answers
19 views

Uniformly magnetized sphere

While working on a uniformly magnetized sphere, I have come across this problem: How does the boundary value equation $$\vec n.(\vec B_2-\vec B_1)=0$$ lead to the equation ...
0
votes
0answers
25 views

Lorentz transformation of scalar field [on hold]

How can I show that $$\phi(x^{\mu}) - \frac{1}{2}\lambda^{\sigma \rho}L_{[\sigma \rho]}\phi(x^{\mu}) = \phi(x^{\mu} + \lambda^{\mu \nu}x_{\nu}) \,\,\, ? $$ Here, $\lambda^{\rho \sigma}$ are the ...
0
votes
0answers
15 views

Relativistic non-linear Walecka model

What is meant by a relativistic non-linear Walecka model? What are some various sources to study it? [And why cannot Google show a satisfactory result to such a simple question?]
-1
votes
0answers
26 views

Search materials by HOMO, LUMO and work function [on hold]

I need to search organic semiconductors for organic photovoltaics (OPV) by their HOMO, LUMO, work function (WF) at 300 K (as I understand, WF cannot be derived from HOMO and LUMO because semiconductor ...
2
votes
7answers
385 views

Can velocity be an undefined quantity?

We have the image below displaying the uniform velocity by time-distance graph. At every point velocity is constant but what if distance and time both become zero as at origin in the graph is? The ...
6
votes
5answers
95 views

Does lunar module need the same amount of fuel for landing and take off?

Let's assume there is no atmosphere and let's assume there is no change in weight due to fuel consumption, will reactive rocket need the same amount of fuel for landing on a planet as for take off? ...
1
vote
1answer
41 views

Delayed Choice Quantum Eraser [duplicate]

All delayed choice quantum eraser experiments I've seen record the signal photons reaching detector D0 and then use the data of the idler photons recorded at detectors D1, D2, D3, D4 to "filter out" ...
1
vote
3answers
59 views

Gravitational time dilation, does time of the observer at a lower gravitational potential looked slowed down in the frame of the higher one

This question is mainly inspired after watching the movie known as Interstellar We knew that for time dilation caused by relativistic motion between A and B. A will measure B's clocks slowing down, ...
-5
votes
1answer
82 views

Could it be possible that the universe doesn't exist [on hold]

Could it be possible that the universe doesn't exist? That nothing exists, not even you or me? And by not existing, I mean totally not existing, as in not even existing as a computer simulation, or a ...
2
votes
2answers
55 views

How to actually account for air resistance?

What's interested me in my studies thus far is that in a lot of beginner undergrad mathematics and physics courses we're often told to calculate trajectories, velocities, etc. by "ignoring air ...
0
votes
0answers
27 views

Best book for learning Quantum Communication [duplicate]

I am new in Quantum physics. I want to do my BSc thesis on Quantum Communication. My major is Communication. So I want to learn fast. I have little idea about quantum computing. So please suggest me ...
1
vote
2answers
40 views

Inclined pulley with unknown hanging mass: when won't the system accelerate?

We have an inclined pulley with angle of $30° $ a block with mass of $10 kg$ placed upon it and It is attached by a rope over a pulley to a mass of $M_A$ which hangs vertically. If $μ_s=0.4$ and ...
6
votes
3answers
721 views

Does quantum entanglement arise from quantum theory or is it merely an experimental observation?

I assume that entanglement emerges from quantum mechanics because the idea was around before experimental verification (e.g the EPR paper). How then does entanglement emerge from the theory (please ...
0
votes
0answers
13 views

Direction, closeness and range of streamlines in a flow domain with solid boundary and free surface?

I have a flow-field with solid boundaries and a free surface, I have plotted the streamlines, however I am not sure whether my graph is correct. In fact, I drew the streamlines by taking a range of ...
0
votes
0answers
35 views

How to calculate the solid-liquid interface energy knowing the surface free energy and liquid contact angle? [on hold]

Given surface free energy something around 20mN/m, and the contact angle around 120° for water (73mN/m). How can I estimate the solid-liquid interface energy of the given solid surface to water? I ...
0
votes
0answers
42 views

Speed of a magnet

What is the speed of two magnets during the congruent moment of their attraction? Theoretically, could a large enough magnet attract a significantly smaller magnet at near the speed of light? In ...
2
votes
2answers
28 views

Why is space isotropic in the vector particle's decay?

I come across one proof the Landau-Yang Theorem, which states that a $J^P=1^+$ particle cannot decay into two photons, in this paper (page 4). The basic idea is, the photon's wavefunction should be ...
-1
votes
0answers
32 views

Momentum in the frame of reference of the center of mass [on hold]

I'm a high school student who just learned this topic in class today. I don't understand why the sum of momentum is zero in the frame of center of mass. Also, how can I solve this problem: Three ...
0
votes
0answers
17 views

Critical engine failure just after rotation: what percent of accelerated slipstream lift does the wing loose? [on hold]

I have searched the web for facts about the lift created by a propeller slipstream (propwash). I have found many web sites that in fact claim that the propeller slipstream does indeed produce a lift ...
1
vote
0answers
16 views

Mutual inductance theoretically decreasing while EMF is increasing in 2 square coil system

I have a quick question regarding electricity and magnetism. I am measuring the induced emf in a square coil of wire with an inductance of 439uH (the other coil is also 439uH and is the same shape). I ...
1
vote
0answers
13 views

LOCAL Temperature Gradient and Stress

I'm investigating the thermo-migration failure mechanism in nanoscale ICs interconnects. Typically, a nano wire under thermal stress suffers from material/mass migration or void nucleation if it ...
0
votes
0answers
20 views

Calculations to Determine Force Required for Gyroscopic Stabalization

I am currently undertaking a project involving gyroscopes, the aim of which is to stabilize a large object. I have read that gyroscopes work because of conservation of angular momentum, and if you ...
-1
votes
1answer
39 views

Quantum Physics, Energy States [on hold]

Which of the following transitions in a hydrogen atom absorbs a photon of the highest energy? a.) $n=2\hspace{1cm}to\hspace{1cm}n=3$ b.) $n=3\hspace{1cm}to\hspace{1cm}n=2$ c.) ...
0
votes
0answers
28 views

How to minimize the wavepacket dispersion?

This is a final exam problem. Here is what I can remember: We know that if an electron's wavefunction starts out as a narrow wavepacket, and moving in a region of constant potential, then the ...
39
votes
11answers
3k views

Why isn't length contraction permanent even though time dilation is?

It's my understanding that when something is going near the speed of light in reference to an observer, time dilation occurs and time goes slower for that fast-moving object. However, when that ...
0
votes
0answers
25 views

Short Wave UV lamp [on hold]

if I remember correctly, shortwave UV is very dangerous such that it can break DNA apart. Today I found this site, where parent can buy some scientific tools for their kids. Do not you think shortwave ...
1
vote
2answers
82 views

Force of a Train

Imagine that there are two trains and the first train is twice as long as the second train. They have the same mass per unit length and they are traveling at exactly the same speed. If the first ...
2
votes
0answers
22 views

Does the surface of austenitic steels have an especially “dynamic” phase somewhere between 100 and 200 Celsius?

There is lots of kitchen lore about pans. One popular concept are the "pores" of a steel pan surface, which are the reason why food sticks to the pan when it's not heated properly. I don't know much ...
3
votes
0answers
74 views

Why (and how) do foods stick to a pan?

We all (sooner or later) have noticed that foods relatively high in protein (especially those low in fat) are very prone to sticking to a pan, or in general to any non-specially-coated metal surface. ...
0
votes
0answers
28 views

Space formed by dot products of three vectors [migrated]

Suppose I have 3 3D unit vectors $\mathbf{v}_1$, $\mathbf{v}_2$, and $\mathbf{V}$. I define the three corresponding scalars $u_1=\mathbf{v}_1 \cdot \mathbf{V}$, $u_2=\mathbf{v}_2 \cdot \mathbf{V}$, ...
-2
votes
0answers
31 views

Convert angular position to wavelength [on hold]

Can you convert angular position to wavelength in spectroscopy? I need know if it's possible. I don't have too much experience in this subject.
2
votes
0answers
39 views

Diffraction grating from first principles

I have realised that a lot of books and online resources fail to give a detailed treatment of the derivation of the diffraction grating interference pattern. Normally only the result is stated. I was ...
0
votes
3answers
135 views

About the double orthogonality of the eigenfunctions of the Hamiltonian

Consider the usual Hamiltonian describing the motion of a particle, $$\hat H = \frac {\hat P^2}{2m} + V(r),$$ where for simplicity the problem can be considered in 1D on the semiaxis $[a, \infty)$ , ...
1
vote
2answers
85 views

Does spacetime have a “mass” value? or What is “Spacetime” made out of?

When measuring the MASS within the Universe, does "space" or "spacetime" have a value? I only ask, because when speaking of expansion, space is expanding. Could it be possible, to reverse the ...
1
vote
1answer
27 views

Confusion about conduction of electricity in a solution

I'm trying to unserstannd conduction of electricity in a solution. Is it correct that anions give their extra electrons to the anode, which transfers the electrons to the cathode, where the cations ...
0
votes
1answer
61 views

Can interacting Hamiltonians always be written in second quantized form?

Is it always possible to write interacting Hamiltonian in a second quantized matrix form like we do it for non-interacting form $$H=\sum _{\alpha\beta}C_\alpha^\dagger h_{\alpha\beta} C_\beta$$ ...
-2
votes
0answers
40 views

Time travel, could it destroy the Universe? [on hold]

One Universe, One mass. In order for "Mass" to be created, (not matter, not energy, but MASS) a creation point where new mass is Incorporated must exist. No "creation" point has ever been observed. ...

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