All Questions
Tagged with time quantum-mechanics
199
questions
-3
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1
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79
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Probabilistic behavior of quantum mechanics [closed]
In a hypothetical scenario, if I were to measure the quantum spin of an electron and it showed "up," and then I traveled back in time without changing the initial conditions, would measuring ...
- 15
3
votes
0
answers
57
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Is there any difference between Wick time order and Dyson time order?
Reading A Guide to Feynman Diagrams in the Many-Body Problem by R. Mattuck, I am getting the feeling that I missed something subtle related to time order. When deriving the Dyson series for the ...
- 5,568
1
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2
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169
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How come time does not commute with $i\hbar\dfrac{\partial}{\partial t}$ but it does so with $H$? [duplicate]
Are they not supposed to be the same operator according to Schrödinger equation?
$$
i\hbar\dfrac{\partial}{\partial t}\psi = H\left(\vec{r},-i\hbar\nabla,t\right)\psi
$$
Apparently $[t,i\hbar\dfrac{\...
- 391
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votes
2
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156
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Are Hilbert spaces in Quantum Mechanics time-dependent?
I'm a mathematician, and am trying to grasp, at least on its surface, the mathematical foundations of quantum mechanics... but there is something that seems just odd with the mathematics.
Suppose i ...
0
votes
2
answers
166
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Commutator of energy and unitary time evolution operator
Edited:-
$\hat{H} = -\frac {\hbar^2}{2m} \frac {\partial^2}{\partial^2 x}~+~V$
$\hat{U}(t) = e^{-iHt/\hbar}$
The Robertson Uncertainty Principle states:-
$\sigma^2_A\sigma^2_B \ge (\frac {1}{2i}[\hat{...
user355398
1
vote
0
answers
171
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The interpretation of Energy-Time uncertainty principle in this article 'Is the universe is a Vaccum Fluctuation?' by Edward Tyron is right or wrong? [duplicate]
This is a screenshot from Edward P Tyron's article "Is The Universe a Vaccum Fluctuation?"
The explanation Energy-time uncertainty principle from Griffiths:
$Δt$ represents the amount of ...
-5
votes
4
answers
170
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Is it possible to define time in a more universal way, such as, time is the outward manifestation of the activities inside an atom? [closed]
Is it possible to define time as the outward manifestation of the activities inside an atom?
For example,
one second is defined as the unperturbed ground state hyperfine
transition frequency of the ...
- 9
0
votes
1
answer
58
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Time switched quantum detection
Two thought experiments -
Modulated double slit
A double slit experiment in which one slit is repeatedly opened and closed. We expect a non-interference pattern when closed and interference pattern ...
- 39
3
votes
3
answers
336
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Understanding time translations
I suppose this question ultimately boils down to: when we speak of a time translation (in nonrelativistic mechanics, so that the Galilean group is the apporpiate symmetry group under which the physics ...
- 1,095
1
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0
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70
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What does fixed and dynamic causal structure mean?
In the following articles: Hardy or Qvarfort. It is said that Newtonian an Quantum mechanics present a finite causal structure while General Relativity and QFT presents a dynamic causal structure.
The ...
-1
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1
answer
109
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Quantum Theory and Time [closed]
I read somewhere that quantum theory requires absolute time and not a dynamic time as described in relativity. Can anyone confirm this and further describe in laymen's terms what quantum theorists ...
- 719
2
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1
answer
145
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Can the energy-time uncertainty principle be applied to rest energy?
In Introduction to Quantum Mechanics (3rd edition) by David J.Griffiths, when deriving the energy-time uncertainty principle，$\Delta $E is defined as $\sigma _H$, the standard deviation of H. And in ...
- 23
0
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1
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58
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Utilizing Switching Mirrors in a Quantum Eraser to Send Binary Information Back in Time [closed]
We know that the information that reaches the detectors in a quantum eraser cannot be used to send information back in time, but I'm thinking there is still a way.
When viewing the results of the ...
- 101
0
votes
1
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229
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What does quantum mechanics have to say about energy density?
Increasing a system's energy density implies increasing certainty about its energy and position. This implies a large uncertainty about the system's time and momentum. Since we know that large energy ...
- 19
4
votes
2
answers
766
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Assigning initial conditions for Schrodinger's equation
I am self-teaching myself quantum mechanics, and my understanding so far is as follows. In the most general case, we would like to find a wave function $\varphi(x,t) \in \mathcal{H}$, where $\mathcal{...
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