All Questions
19 questions
0votes
2answers
79views
Interpretation of Heisenberg Uncertainty Relation
If $A$ is an observable and $\psi$ the state of a quantum mechanical system, then the inner product $E_A(\psi)=(A\psi,\psi)$ is the mean of observed values of $A$ in state $\psi$. Likewise $E_{A^2}(\...
- 37
-1votes
2answers
145views
Is Schrodinger's cat a problem of how we define identity?
I apologize if the question is somehow silly or useless. I was reading about the infamous Schrödinger's cat paradox and I thought that if we consider that a cat is composed of numerous atomic ...
1vote
1answer
51views
Wavefunction with determinate momentum
In page 100 Griffiths' Introduction to Quantum Mechanics, Griffiths states that the eigenvector of $\hat{p}$ in the position basis is $\frac{1}{\sqrt {2\pi\hbar}}e^{\frac{ipx}{\hbar}}$ and states that ...
- 145
9votes
2answers
425views
In quantum mechanics, can we measure anything else than position?
In the basic quantum mechanics lectures, we learn that we can measure any observable. That means mathematically, all Hermitian operators correspond to a physically measurable quantity. In strong ...
- 3,390
1vote
2answers
275views
If the Many world interpretation is correct, is a single observer "privileged" in the experienced world?
I've been interested lately in the many worlds interpretation of quantum theory - it seems like the most straightforward and likely formalism that exists. As per this theory, when an observer observes ...
6votes
1answer
500views
What is the set of observables of a quantum system?
This is a question I am wondering about because the answer to it seems to have some interesting - but perhaps already long considered and dismissed because it's been settled - implications for the ...
- 20.9k
2votes
1answer
533views
Are the paths in a Feynman path integral not observable?
The only quantity that appears after doing a Feynman path integral evaluation is the propagator which is used to compute different observables. The paths in the FPI don't appear anywhere in the ...
- 3,103
1vote
0answers
53views
Does QM talk about reality in itself or our observation of it? [closed]
I am not a physicist and I've recently started watching introductory lectures on QM on youtube (MIT, Stanford) and reading the Feynman lectures. I have a high-school level knowledge of Math so I'm not ...
user222936
3votes
4answers
1kviews
What is a physical example of an observable with degenerate eigenvalues? [closed]
If eigenvalues of an observable have the physical meaning of a possible result after a measurement, what's the interpretation of degenerate eigenvalues, and what is an example of such an observable?
- 132
2votes
1answer
148views
Could there be any situation where two noncommuting observables are simultaneously considered?
As physicist Robert Griffiths (one of the founders of the 'Consistent Histories' formalism) says: "Two physical variables whose operators do not commute correspond to incompatible sample spaces, and ...
- 3,018
23votes
5answers
1kviews
What is the physical meaning of the sum of two non-commuting observables?
Scenario: ${\mathcal A}$ and ${\mathcal B}$ are two observables. Mathematically we model them by two Hermitian operators $A\colon H \to H$ and $B\colon H \to H$ on a separable Hilbert space. ...
6votes
4answers
399views
Why are observables hermitian operators in the Everett interpretation?
Observables correspond to hermitian operators on the quantum state. But in the Everett interpretation, the wave function doesn’t collapse since we consider the entire universe as a single quantum ...
- 1,918
0votes
2answers
732views
Physical quantities have definite values?
I don't really know if this question has an anwser but I thought it was worth to try asking. My point here is the following: in Quantum Mechanics, to describe the states of a system we use a Hilbert ...
- 37.9k
2votes
3answers
1kviews
What happens with a tunneling particle when its momentum is imaginary in QM?
In classical mechanics the motion of a particle is bounded if it is trapped in a potential well. In quantum mechanics this is no longer the case and there is a non zero probability of the particle to ...
- 2,179
7votes
2answers
351views
Basic Interpretation of Compostion of Observables and their Measurement
Given two (or more) observables $A, B$ which commute one can construct a third observable $C= A \circ B$. If $\psi$ is a common eigenvector of $A, B$ with eigenvalues $\lambda_1, \lambda_2$ then it is ...
