Uncertainty principle Definition and 556 Threads

A Qbit with up probability 1 - (10^-75) would most likely still produce a reading of up, so an up reading does not mean that the up probability is 1.0 to millions of decimal places. The spin detector is a physical device made of atoms. None of its surfaces are pure mathematical planes or...

Consider the measurement problem for an electron in a single-slit experiment done one electron at a time. There are two interlinked questions, but some consider just one of them to be the actual measurement problem. The first question is concentration - a fairly uncertain distribution condenses...

Here is my thought experiment: Let's say I attenuate a very short laser pulse to single photon intensity. Due to the uncertainty principle, I know the time of arrival of the photons, but not their energy. So let's reverse that by splitting the pulse in its spectral components with a diffraction...

I calculated the answer for question a to be about 10^-6 m/s (1 significant figure), but I am stuck on question b. It seems to me that it is a trick question because we don't know anything about the speed in the y-direction, and the answer can be everything from 0 to infinity. Am I right?

How accurate of a measurement can we make on the position of a particle? I heard you need more and more energy to get a measurement more accurate. Would the energy needed to be infinitesimal accurate create a black hole upon. Measurement?

I have a question related to the uncertainty principle in QFT and if it is related to the early universe conditions. Do we still have four-vector momentum and position uncertainty relation in relativistic quantum theory? I have been following the argument related to the early universe and the...

I understand that the uncertainty is low when you're dealing with a "macro" scale area that is much bigger than Planck's constant. But what's confusing to me is when you know with extreme precision the location, but there's so many particles involved that there is little uncertainty since the...

As I understand it the principle states that the more accurately you measure one factor of an object, for example speed, the less you can tell of any other factors, for example position. To me this seems we will every only be able to measure an approximation of reality and thus determinism...

Soo. I think this problem is too direct and easy so I think I got it in wrong way: p=h/r and then plug in the K and V and then we get E=E(r) and get derivative and we have minimum? What do you think? is there sth I am missing?

I'm studying orbital angular momentum in the quantum domain, and I've come up with the Robertson uncertainty relation for the components of orbital angular momentum. Therefore, I read that it is necessary to pay attention to the triviality problem, because in the case where the commutator is...

We know that both momentum and position can not be known precisely simultaneously. The more precisely momentum is known means position is more uncertain. In fact, as I understand quantum mechanics, position probability never extends to 0% anywhere in the universe (except at infinity) for any...

Per the Heisenberg uncertainty principle, a particle does not have a precisely defined location. Does such uncertainty contribute to the transfer of thermal energy (i.e. entropy)? Is uncertainty the primary means for the transfer of thermal energy at the quantum level?

Hello, 2 questions please about the Uncertainty Principle and the following scenario: I shoot at each other, 2 electrons each with equal but opposite velocity such that they repel each other? (To me, this indicates that you know the momentum of each electron and you know each position...

I am guessing time-energy uncertainty relation is the way to solve this. I solved the Schrodinger equation for both the regions and used to continuity at ##x=-a, 0,a## and got ##\psi(-a<x<0) = A\sin(\kappa(x+a))## and ##\psi(0<x<a) = -A\sin(\kappa(x-a))## where ##\kappa^2 = 2mE/\hbar^2##...

Could this statement be the first step towards quantum gravity? Or is it trivial or not true at all?

With the double slit, experiment we show the double nature of light and matter as wave and particle. In particular, the so called "which way" thought experiment illustrate the complementary principle. In my book, this experiment is analyzed putting a series of particles in front of one of the...

The general uncertainty principle is derived to be: \sigma_A^2 \sigma_B^2 \geq \left(\frac{1}{2} \langle \{A,B\} \rangle -\langle A \rangle \langle B \rangle \right)^2 + \left(\frac{1}{2i} \langle [A,B] \rangle \right)^2 Then it is often "simplified" to be: \sigma_A^2 \sigma_B^2 \geq...

hi guys i am trying to follow a proof of the generalized uncertainty principle and i am stuck at the last step : i am not sure why he put these relations in (4.20) : $$(\Delta\;C)^{2} = \bra{\psi}A^{2}\ket{\psi}$$ $$(\Delta\;D)^{2} = \bra{\psi}B^{2}\ket{\psi}$$ i tried to prove these using the...

Homework Statement:: i saw this simple derivation of the uncertainty principle in my college introductory quantum book Relevant Equations:: Δp.Δx = h hi guys i saw this derivation of the uncertainty principle in my college quantum book , but the derivation seems very simple and sloppy , i...

Hi! I am checking Zettili's explanation on the uncertainty principle and I have this confusion on what the "uncertainty" really means which arises from the following statements: When introducing the uncertainty principle, for the case of position and momentum it states that: if the x-component...

In the Heisenberg's uncertainty principle ## \triangle x \triangle p \geqslant \frac{\hbar}{2} ## what happens when the uncertainty in position becomes very small is that the uncertainty in momentum becomes very large. But what happens when the spread of the uncertainty in momentum becomes...

Maxwell's demon measures the position and velocity of the particle. How can it do that when it violates the uncertainty principle? Does that mean uncertainty principle is unavoidable otherwise we will violate II law of thermodynamics as in the case of Maxwell's demon?

Hello, So I know that the magnetic moments of atoms are dependent on the spin and orbital angular momenta of its electrons. Both of these quantities are limited by the uncertainty principle so that neither of their direction and magnitude can be known simultaneously with arbitrary precision...

In Scientific American, July 2020, the article "The Darkest Particle" by Louis and Van de Water, page 46, discussing the hypothetical sterile neutrino, there is the sentence: "Because sterile neutrinos are likely to be more massive than the regular flavors, however, particles could make the...

So according to Heisenberg's energy-time uncertainty principle, the product of accuracies in energy and time is equal to ћ/2. In this problem, I know I have to calculate ΔE. But when I'm using Δt = 1.4e10 yrs. = 4.41e17 s, I am getting ΔE = 0.743e-33 eV, which is certainly incorrect! Where am I...

Hello everyone, Heisenberg's uncertainty principle tells us that we cannot measure the position and the momentum of a particle to infinite accuracy. My question is, can we use general relativity to overcome this difficulty? From what I know, any mass can curve spacetime even if it was small, and...

I just read the Feynman Lectures about the electron gun experiment with two holes in the middle wall. It demonstrates that if we don't look at the electrons while they travel toward the detector there is an interference pattern in the probability curve of the electrons similarly to what happens...

If I understand correctly (a big caveat), one shows that if one can get from one function to the other via a Fourier transform and multiplication by a constant, then the width of the corresponding Gaussian wave of one gets larger as that of the other gets smaller, and vice-versa, and by a bit...

why can't we know where electron goes after it was hit by light? Light has a travel direction, can't we assume that electron bounces to the same direction that the light was headed??

In quantum mechanics the name is Uncertainty principle. But outside of QM, what is the name for those inequalities?

I have no idea how to approach. Hence would appreciate any help

Hi there, I'm very stuck on this problem when approaching it like this. I know I could use the Landau Criterion for rotons but that's not accepted here, it wants the approach to come from the uncertainty principle. My thinking is along these lines: There will be a change in chemical potential...

"Now, if an electron has a definite momentum p, (i.e.del p = 0), by the de Broglie relation, it has a definite wavelength.A wave of definite (single) wavelength extends all over space. By Born’s probability interpretation this means that the electron is not localised in any finite region of...

The uncertainty principle shows that position and momentum are mathematically entangled. There are a set of these entangled properties:x mvt E. .. .. .etc.Is there a complete list? Is spin entangled? If so, what with? What sort of properties aren't...

Just wondering, perhaps I'm thinking flawed so please inform me if I have a misconception. I've been told numerous times by many people that reaching absolute zero temperature is impossible, but none of those people have offered an explanation. This has always bugged me and I was thinking the...

I've read an article about a gedanken experiment that einstien proposed sometime in the late 40s I think.It ran like this. Lets say you initiate a reaction in a molecule in which two particles are emitted. By the laws of the conservation of momentum the particles both leave the molecule...

This was emailed to me, and I might as well post it. Presumably the author wished to retain anonymity. It in no way represents my view etc, and may be nonsense etc... However, I urge the more knowledgable member to look on it, and comment as neccessary.------------------------THE UNCERTAINTY...

What is the simplest form for the uncertainty principle in plain English without loss of too much precision? What does it really say?"Half the information assoscated with sub atomic particles is missing" perhaps? Can this be inferred? Does it actually say something else?42 is just another number

I talked to this physicist guy the other day,and he said SR fully explains\implys the uncertainty principle.I didn`t know this.But when I think about it, it does seem to work.Is this true?Can anyone give a layman explaination of SR implying the UP?meemoe_ukReader of John Gribbin's " In search...

let be dxdp>h/2Pi the uncertainty principle applied to momentum and x coordinate..then if dx=0, dp=infinite..but the maximum uncertaninty in momentum we can have is indeed..dp=mc where c is the speed of light (nothing can go faster than light) so appliying uncertainty principle then we would...

i know the answer is no.but the only way i can see the uncertainty principle can be proven wrong is to take a object that is in motion that is large and shrink it till it reaches the molecular level to predict it position and velocity. so what i suggest is we take a cube of ice in a heated...

I am reading about zero point energy, and I came across this:"...the uncertainty principle states that no particle can ever have precise values of position and velocity simultaneously; thus, particles can never come completely to rest."Is that right? I had thought that it should go more like "no...

This was emailed to me, and I might as well post it. Presumably the author wished to retain anonymity. It in no way represents my view etc, and may be nonsense etc... However, I urge the more knowledgable member to look on it, and comment as neccessary.------------------------THE UNCERTAINTY...

Bose Einstein Condensate:In 1995 scientists cooled rubidium atoms to temperatures of approx. 20 nanokelvins, and then attempted to calculate the velocity of these atoms. (the kinetic molecular theory predicts a typical gas having a velocity of approx. 1000 mi/h). Now at 20 nanokelvins (near...

The uncertainy principle. I am familiar with this concept in physics however i am only familiar enough to doubt that the catayst for this concept has little to no signifcance. The catalyst, from what i know, is that it has been decided that any attempt to get an exact knowlege of both the speed...

Does Heisenburg's uncertainty princlaple only work on a quantum scale and if it does then why can we not predict the future because the uncertainty principle would allow it?

Does Heisenburg's uncertainty princlaple only work on a quantum scale and if it does then why can we not predict the future because the uncertainty principle would allow it?

No scientific idea in the last century has been more misunderstood and abused, by vulgar and learned alike, than Heisenberg's Uncertainty Principle...Read complete article at<http://www.chorion.org/core/files/science/slate_uncertainty.txt>-...

So with the \gamma=\frac{1}{\sqrt{1-\beta^2}} it seems obvious that relativistic momentum, p=\gamma m_o v is supposed to be used. Then \frac{ dp}{dv}=m_o(1-\beta^2)^{-1/2}+m_o v...