Tagged Questions
1
vote
0answers
62 views
Quantum field theory quote
I have read this in scientific American:
According to quantum field theory, all particles spend a little time as combinations of all other particles"
Is this right? How long? And how can they be a ...
2
votes
2answers
64 views
Hamiltonian of Harmonic Oscillator with Spin Term
We have the usual Hamiltonian for the 1D Harmonic Oscillator:
$\hat{H_{0}}=\frac{\hat{P^2}}{2m} + \frac{1}{2}m \omega \hat{X^2}$
Now a new term has been added to the Hamiltonian, $\hat{H} = ...
2
votes
1answer
67 views
Atomic physics through classical resonance?
I have a rather general question regarding the theory of Quantum Mechanics. To preface this question, consider a violin string. When a violinist exposes the string to a bow, this is exposing the ...
0
votes
0answers
17 views
Allowed Quantum States- Filkelstein and Rubinstein constraints
So basically i'm doing a report on Finkelstein and Rubinstein constraints. I have a system where the allowed quantum states satisfy ...
8
votes
3answers
178 views
Is $k_B \rightarrow 0$ the classical limit of stat. mech., as $\hbar \rightarrow 0$ is in QM?
I hear very often among my peers and seniors that just as how $\hbar\rightarrow0$ takes me to classical mechanics from quantum mechanics, $k_B\rightarrow0$ will take me to classical thermodynamics ...
1
vote
1answer
62 views
Diffraction through the slit
In book "Quantum Mechanics and Path Integral", 3-2 Diffraction through the slit:
Under the fig. 3-3, why did Feynman say that we cannot approach the problem by a single application of the ...
2
votes
2answers
124 views
Hamiltonian of a water molecule bounded to a surface
Where can I find a way to construct the hamiltonian of a water molecule bounded to a surface? More generally,how can one write the hamiltonian of an atom bounded to a surface?
3
votes
0answers
116 views
Symmetries of separable potential
For separable potential, say $x^4+y^4$, its symmetry are degenerate.
Is that a generic case to every separable potential? I will explain my question:
The potential $x^4+y^4$ has $A_1, B_1, A_2, B_2, ...
1
vote
1answer
373 views
Conjugate Variables and Fourier Transforms in Classical Physics
Let q be a generalized coordinate with a conjugate momentum p and a potential resulting in a periodic motion of q. What is the meaning of the Fourier transform of q(t) over its period? Can this be ...
5
votes
2answers
169 views
Tracking photon color in Bell experiments
In parametric down-conversion, it is said that a driving photon is converted into two entangled photons whose frequencies add up to the driving frequency. Yet in discussions about entanglement ...
3
votes
1answer
180 views
Coincidence detectors in Bell tests: How close is close enough?
When is a coincidence a coincidence? We know that to identify entangled photons, the electronics is set to look for simultaneous clicks at opposite detectors. The size of the window is to some degree ...
7
votes
2answers
603 views
Forget Hooke's law. Why does a spring exert a force?
Forgetting Hooke's law for a minute why, from a microscopic perspective (preferably quantum) on up to a macroscopic one, does a spring under tension exert a force?
I was thinking that there might be ...
-1
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1answer
194 views
purely hypothetically, could a quantum being appear to be human? I ask for the purpose of research on a novel [closed]
I am a budding novelist, and im researching a few things for a fictional narrative. the characters are from other dimensions and i want to present a coherent scientific structure. any suggestions ...
2
votes
1answer
501 views
Does decoherence explain all instances of wave function collapse?
Specifically, how can decoherence explain the appearance of flecks of metallic silver on a photographic plate when exposed to the very weak light of a distant star?
EDIT: Perhaps the advocates of ...
4
votes
4answers
490 views
Are the physical laws scale-dependent?
If you read the article "More Is Different", by P.W. Anderson (Science, 4 August 1972), you will find a deep question: are the physical laws dependent of the size of the system under study?
As an ...
