Questions tagged [heisenberg-uncertainty-principle]
This tag is for Heisenberg's quantum mechanical uncertainty principle. DO NOT USE THIS TAG for uncertainty in a non-quantum measurement.
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Use delaunay variables to express perturbation in Hamiltonian function [duplicate]
I am working on orbit uncertainty propagation, where the initial position and velocity define the uncertainty. I want to construct an orbit that is determined by Delaunay variables.
Now I just know ...
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Beating the uncertainty principle for musicians
https://www.phys.unsw.edu.au/jw/uncertainty.html
The musician's uncertainty principle as above states that tuning can be less precise in short notes. But when we have a string with knowing its ...
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Quantum vs classical behavior of monochromatic light
A polarized beam of monochromatic light in classical physics is described by something like
$$E = \hat z \cos(kx-\omega t),\quad B =\hat z\times E.$$
What happens if we aim this beam to a highly ...
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As Bob Falls Into The Event Horizon, Does the Size and Shape of His Image Change?
I see several questions related to mine, but none of them address the size and shape of the remote image of Bob as he falls into the event horizon.
Matt McIrvin's Physics FAQ says:
So if you, ...
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Energy Conservation for Quantum Systems
This seems like a basic question but I couldn't find the answer when looking online. I'm in an introductory quantum mechanics class and we learned how classical laws can be seen in QM when you look at ...
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Does Heisenberg uncertainty principle and chaos theory create indeterminism? [duplicate]
I’ve been struggling to understand this and hoping for an answer from someone enlightened.
Heisenberg Uncertainty Principle states there is a trade off between how much we can know about position and ...
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Time evolution of the uncertainty principle
I've written the following proof:
Let $A,B$ be observables (Hermitian operators). define $ ΔA:=A-<A> $.
the uncertainty principle is: $$ ⟨(ΔA)^2⟩⟨(ΔB)^2⟩ ≥|⟨[A,B]⟩|^2/4 $$
The Heisenberg ...
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Why can’t we define both position and momentum precisely? [closed]
In quantum mechanics, it is often stated that we cannot simultaneously define the exact position and momentum of a particle, as expressed by the Heisenberg uncertainty principle. This has left me ...
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”Heisenberg-like” uncertainty principle(s) for antennas?
In harmonic analysis, we have the (one-dimensional) uncertainty principle:
$$\left(\displaystyle\int\limits_{-\infty }^{\infty }x^{2}|f(x)|^{2} \, \mathrm dx\right)\left(\displaystyle\int\limits _{-\...
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Uncertainty Principle and boundedness of the Hamiltonian
In then statistical mechanics book by R.K. Pathria & P.D. Beale (page 82-3rd edition), while discussing positive/negative temperatures, the author states:
"the uncertainty principle alone is ...
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Do quantum entities lack definite positions because of measurement limits, or is it a fundamental feature of nature? [duplicate]
In quantum mechanics, particles such as electrons do not have a fixed position until they are measured
Questions:
Is this indeterminacy simply due to the limitations of our current measurement ...
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Quantum model of atom [duplicate]
When I was analyzing the structure of the atom (i'm new at this), the problem arose in the understanding of the motion of the electron. I realized that the electron cloud is just the probability of ...
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Measuring quantum velocity by measuring position at two instant separated by $dt$. Final state is in position eigenstate, not momentum...?
My question is closely related to this one, but it asks a more precise/different confusion I have.
I consider a free quantum particule starting in the position eigenstate $|x_0\rangle$, at time $t_0$.
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"Paradox" in Heisenberg uncertainty principle
I am confused about the following thought experiment.
Consider a free particle: $H=\frac{\widehat{p}^2}{2m}$
Assume that the particle is at time $t=0$ in an eigenposition state $|x_0\rangle$.
The goal ...
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Position/momentum uncertainty "principle" : why is the velocity defined as $p/m$. Shouldn't we define it with group velocity?
In wave mechanics, the usual way to define the velocity of the wave is with the group velocity: $v_g = \frac{d \omega}{d k}$. The reason why can be understood from this Wikipedia page.
A wavefunction ...
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