All Questions
1
vote
0answers
10 views
What's happening when a force is applied but there's no displacement?
I've thought of an example that can explain my doubt properly.
Let's take an electric motor which is connected with an object through a rope so that when the motor starts to rotate, it brings the ...
0
votes
0answers
5 views
supernova 1987a: space-like interval?
In 'spacetime physics' E. Taylor says the supernova 1987a is a nice example for a space-like spacetime interval. But I don't understand why? What's the reasoning ?
1
vote
0answers
14 views
How can we experimentally tell the difference between particles with and without rest mass?
We only observe their decay products and that is what the rest-mass is reconstructed from.
Also, there is a whole issue of running coupling which means that rest mass per se actually doesn't make ...
-1
votes
0answers
10 views
Calibration of the sensor?
I am doing calibration of a sensor, where the uncertainty of the sensor measured physically for our system to known uncertainty of the system. Now I choose to do the calibration of stereo camera, as ...
0
votes
0answers
21 views
Modification of Poisson equation
I am looking for properties of the following equation
$$\Delta\phi+(\nabla \phi)^2=4\pi\rho$$
Is there any name of this equation ? (If yes, it would be easier to find some information).
1
vote
1answer
28 views
Understanding quantum spin
I'm trying to get an idea of what spin in quantum mechanics means. I have the following questions regarding spin:
The eigenvalues of the operator corresponding to the z component of spin is $\hat{S}_{...
0
votes
1answer
15 views
Problem regarding Buoyancy forces and Archimedes principle
A thin-walled container of mass $m$ floats vertically at the separation surface of the two liquids of density $ρ_1$ and $ρ_2$ . The whole mass of the container is concentrated in the part of height $...
-6
votes
1answer
30 views
Is the definition of the meter arbitrary?
From Wikipedia, the definition of the meter is
The meter is defined as the distance traveled by light in a vacuum in 1/299792458 seconds.
Why is this number of seconds chosen? Is there a ...
-1
votes
0answers
16 views
Divergence of an electromagnetic wave's electric field
For an electromagnetic wave propagating along the earth, what can one say about the divergence of the electric field?
Is $\nabla.E = 0 $?
I know this is the case in a vacuum but does it change when ...
0
votes
1answer
18 views
On Information-less systems
Is there any system in the universe that is information less, I.e., has or possesses no physical information. For example if I have a system of particles and if I throw this system into a black hole(...
0
votes
1answer
9 views
What color I see objects with a green glass in a room lightened by red light?
Suppose the only light source in a room is red light.
What would see an observer with a green eyeglasses?
0
votes
1answer
36 views
Stationary states may not be stationary waves: Something is moving. What?
The plane wave state for a free particle given by $\psi(x,t)=A\exp[i(kx-\omega t)]$ is completely delocalized in space and time. Therefore, the wavefunction is present everywhere in space at all times....
0
votes
0answers
11 views
baryon vs meson, or how can quarks occupy the same space
Baryons are "fermions" of spin −1/2+N−1/2+N (an integer), which means that they behave like ordinary matter (i.e. to oversimplify, you can't have two of them in the same place at the same time),
...
1
vote
1answer
21 views
Particle with spin in uniform magnetic field
In the text "Introduction to Quantum Mechanics" by Griffiths the following is stated: The magnetic dipole moment $\vec{\mu}$ is proportional to its spin angular momentum $\vec{S}$: $$\vec{\mu} = \...
0
votes
1answer
18 views
How does the superposition principle relate to the copenhagen interpretation?
Does the idea of superposition only exist under the Copenhagen interpretation of quantum mechanics?
If that is not the case, does it exist under all intepretations/theories of quantum mechanics?
How ...
