0
votes
0answers
30 views

Upper division physics lab — Project ideas [on hold]

As an experimentalist, I am very excited to be taking my first upper division physics lab next semester! The course covers basic electronics (filters, diodes, transistors, op-amps, analog & ...
0
votes
0answers
23 views

Frictional loss of matter

How do we account for the loss of matter from an object due to friction ? Is it simply a phenomenon or result of any other process ? Eg :The loss of matter from the rubber tyre
1
vote
1answer
17 views

How do you work out the energy requirement for a submerged pump?

I was wondering if you were to place a pump in a submerged container and then were to open a hatch allowing water to flood the previously vacant cavity how much energy would be required to discharge ...
0
votes
0answers
13 views

What is trivial and non-trivial gate in computing?

My question seems like it should be posted in Computer Engineering section, but below is how I found this word. I was reading the textbook: Quantum Computation And Quantum Information - by Michael A. ...
3
votes
1answer
60 views

Are fundamental forces always attractive/repulsive, i.e. parallel to the separation?

If magnetic monopoles existed it would not be the case - the forces on an electron and a magnetic monopole passing by each other would be at right angles to the vector connecting the two particles! ...
2
votes
0answers
35 views

Lorentz transformation - Bjorken & Drell

I'm trying to derive (14.25) in Bjorken & Drell (B&D) QFT. This is $$\tag{14.25}U(\epsilon)A^\mu(x)U^{-1}(\epsilon) = A^\mu(x') - \epsilon^{\mu\nu}A_\nu(x') + \frac{\partial ...
0
votes
1answer
26 views

What unit of distance to use when calculating power loss?

80% of Earth's atmosphere is within 10 miles of Earth's surface. I know that power attenuates inversely as the square of the distance within the atmosphere so it occurs to me that a 50,000 watt signal ...
-1
votes
3answers
68 views

When we catch a falling object, where does its kinetic energy go?

Some of it is transformed into heat and noise, but where does the rest go? Further details: The object does not bounce off (e.g. a sack of rice marble ball). The hand remains completely static ...
2
votes
2answers
69 views

How would gravitons couple to the Stress-Energy tensor?

How would gravitons couple to the Stress-Energy tensor $T^{\mu\nu}$? How did physicists arrive at this result? I've read that it follows from the analysis of irreducible representations of the ...
-1
votes
0answers
42 views

Double slit experiment setup which resolves dualism

Suppose we have the following setup of double-slit experiment: A point source of coherent photons emits them so that they fall onto a non-transparent panel D ...
0
votes
0answers
34 views

work done for time dependent Hamiltonian

I want to calculate work done by external force when my Hamiltonian is described by $$\hat{H} = \hat{H}_{0} + F(t)\hat{A}$$ According to First law of termodynamics $$dE = \delta W$$ so, $$E = ...
0
votes
0answers
25 views

Can the strong force be explained by quaternions?

I wonder if the strong force can be explained by quaternions without the use of matrices. I heard that it could, but the source was not reliable.
3
votes
1answer
93 views

Light in a box with positron walls instead of electrons

I understand that with a hollow cube with the inner walls covered in mirrors given a light source briefly, the light would eventually be absorbed. This is due to electron excitation I believe. So ...
0
votes
1answer
94 views

Is imaginary time a fifth dimension? [duplicate]

I've read that by introducing the concept of imaginary time, the dimension of time can be treated like a spatial dimension mathematically. Assuming, without imaginary time, one considers the universe ...
2
votes
0answers
39 views

Time functions in general relativity

In my general relativity notes a function $f$ is called time function, if $\nabla f$ is time-like past-pointing. Say that we are in Schwarzschild spacetime and I want to check if $f=t$ is a time ...
0
votes
2answers
42 views

Photon walk in stars with convection

I'm having trouble figuring this out. I've read, that when photons are created via nuclear processes inside a star, it can take about 1 million years for photons to actually reach the surface of a ...
-1
votes
0answers
37 views

How to derive the light pressure from maxwell equations? [on hold]

Is there any reference? Was the idea of radiation pressure known to Maxwell himself?
-1
votes
1answer
32 views

Projectile at an angle. Finding the angle using conservation of energy [on hold]

Ball is thrown at an angle α and at the highest point it's potential and kinetic energy are the same. Find the angle. Use the law of energy conservation. What the professor wanted $mV^2/2 = 2* ...
1
vote
1answer
62 views

Turning off point for 1g acceleration

Let's say I am on a ship accelerating with 1g. I want to keep the engine running for half a year ( to an observer from my point of origin ) but due to time dilation it would have to be sooner than ...
-4
votes
1answer
35 views

Does light or waves have any kind of mass? [duplicate]

Just like the previous question, Even I have been studying Hawking's A Brief History Of Time and even I was thinking of Einstein's General Relativity. But I was unable to accept his view of GRAVITY. ...
7
votes
1answer
63 views

Twin paradox, different starting locations

Let's say I have a twin who is at rest relative to myself and ten light years away from me, we are both in rocket ships. We have agreed that I will send a laser pulse and that when he receives it we ...
0
votes
1answer
90 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
42 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
32 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
19 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
810 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
69 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
113 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
38 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
54 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
18 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
14 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
25 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
378 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 ...
5
votes
4answers
80 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
40 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
50 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, ...
-4
votes
1answer
72 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
37 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
710 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
12 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
34 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 ...

15 30 50 per page