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### What is $\Delta t$ in the time-energy uncertainty principle?

In non-relativistic QM, the $\Delta E$ in the time-energy uncertainty principle is the limiting standard deviation of the set of energy measurements of $n$ identically prepared systems as $n$ goes to ...
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### Why is it impossible to measure position and momentum at the same time with arbitrary precision?

I'm aware of the uncertainty principle that doesn't allow $\Delta x$ and $\Delta p$ to be both arbitrarily close to zero. I understand this by looking at the wave function and seeing that if one is ...
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### What does Heisenberg's uncertainty principle tell about nature? [closed]

I agree with the fact that the principle points out to the inaccuracy in the measurement of the two quantities of the particles (momentum and position). But measurements apart, does it explain ...
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### How can I accurately state the uncertainty principle?

In almost every introductory course, it is taught that the uncertainty principle happens due to disturbance in the system to be measured. Teachers give these examples that induce students to ...
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### Do quantum measurements violate conservation laws?

When we measure the spin angular momentum of a particle in an axis different to its current spin, we change the direction of its spin, which taken by itself would be a violation of the law of ...
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### Physical interpretation of Uncertainty

Uncertainty of an operator $\hat{A}$ when observing a state $|\psi\rangle$ is defined as \begin{equation} \Delta A_{\psi} = |(\hat{A} - \langle\hat{A}\rangle)\psi| \end{equation} Now assume that there ...
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### Uncertainty principle: for an individual particle?

In some textbooks about quantum mechanics, the position-momentum uncertainty principle is treated as being valid for an individual "particle", with $\Delta x\cdot\Delta p\geq\hbar/2$ ...
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### What happens to Pauli's argument (that says that there is no time operator) when applied to $X$ operator for some simple systems?

An argument by Pauli is usually referred to in the literature when it is stated that there cannot be a time operator in quantum mechanics. This argument can be found as a footnote to P63 of W. Pauli, ...
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### A problem with the uncertainty principle [closed]

It is postulated that the particle is described by a state vector $\Phi$, which is an element of Hilbert space. Let's suppose that there are two Hermitian operators $A$ and $B$, representing two ...
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### Is there any difference between expectation value and average value in quantum mechanics?

Is there any difference between expectation value and average value in quantum mechanics? If there is no difference then why give them different names?