Uncertainty principle Definition and 541 Threads

I have a quite simple doubt. One of the practical applications of Heisenberg's uncertainty principle is given by Heisenberg's microscope. In this thought expt. Heisenberg imagines of a hypothetical microscope in which an observer attempts to measure the position and momentum of an electron...

hi, I have a question about the uncertainty principle. if an electron is in attractive OR repulsive electromagnetic field, is its uncertainty about its position lower than if it is a free electron? I believe particles are more random, with a higher entropy when there is less...

I was reading about this, but I'm unclear on something. Does the Heisenberg principle arise due to limitations in technology? Or is it an absolute physical phenomena that can't be avoided no matter how advanced your measuring tools are?

Gravity effects time in such a way that you can visualize it on a scale such as: |-----|-----|-----|-----| <- Earth Scale in Seconds |-----------|-----------| <-Deep Space Scale in Seconds(Exaggerated) I'm trying to visualize how this time effect would effect...

I've been trying to understand the uncertainty principle and so far the Wikipedia definition has been very good explainig position and momentum relationship, but the aperture size explanation below is beyond me. Any help? "If a large aperture is used for the microscope, the electron's...

I hope a pointer to a speculative post on a blog is OK in this group. But as the posting rules at https://www.physicsforums.com/showthread.php?t=5374 reference a dead page, I was unable to check ;-) (It would be easy to copy and paste that article here, if that is considered desirable to...

There is something (among many things of course) that confuses me with the uncertainty principle as it pertains to position and momentum of a photon. If one shoots a photon of red light, for example, at a screen, one can see where exactly the photon hits the screen so position is known. Also...

I appologize if my questions make no sense (very likely as I do not have a physics background). 1. The uncertainty principle states that precision of measurement is identified only down to the Planck's constant. If this is so, how can one measure the speed of light with infinite precision? ANd...

If we've perfectly located all of that mass, doesn't its momentum have to be infinetly or maximally dispersed. It would be a slow motion big bang from our frame because of space and time contraction and we couldn't even see it, but it seems like the mass should disperse in some diffraction pattern.

Homework Statement Let's say T is kinetic energy and V is Potential. Then, find a principle between T and V by using dA^2dB^2 (larger or equal) {(1/2i)(<[A,B]>)}^2 3. The Attempt at a Solution First I try to find commutator of T and V, [T,V] then it gives little bit dirty...

I've been following Peter Lynds work- which is a periodic rediscovery of the philosophical difficulties surrounding the concept of discontinuity, threshold, edge etc and its application to Zeno's paradox. Lynds' solution has emerged a number of times in showing the paradox is invalid because...

Homework Statement Estimate the kinetic energy of a constituent quark of mass 300 MeV/c^2 confined insdide a proton of radius 1 fm Homework Equations Heisenberg's uncertainty principle \Delta x \Delta p \approx \hbar (1) Kinetic energy T=\frac{p^2}{2m} (2) The Attempt at a...

Uncertainty Principle Questions!PLease HELP! Homework Statement 1. Since a charged pi meson at rest exists on average for only 26 ns, its energy cannot be measured with unlimited precision. Determine the minimum uncertainty in the meson's rest energy. 2. Determine the minimum uncertainty in...

We have the uncertainty principle. How would our world be different, if someone measured position and momentum of a particle with 100% accuracy? Would some other laws of physics be violated, too? I mean - what laws of physics depend on uncertainty? It is clear to me, that the whole...

From what I understand, the Heisenberg Uncertainty Principle means that we can never know the position and velocity of a particle at the same time, as the measurement of one necessarily affects the measurement of the other. Great. I understand that theory, and it makes perfect sense. But what...

I got in an argument with my dad over the weekend. Is the Heisenberg uncertainty principle a result of technological limitation or a basic premise in quantum mechanics? Basically is the information fundamentally "unknowable" or simply unmeasurable?

In non-relativistic wave mechanics, the momentum-position uncertainty relationship and the energy-time relationship exist because these variables are related via the Fourier Transform of the wave function. Is there a relativistic (QFT) equivalent or analog of the above px and Et uncertainty...

what is uncertainty principle? thanks ppl..

i have two questions that i am struggling with and i have tried all i can think of with them and i am still not getting the answers correct. 1)Estimate, using the Uncertainty Principle, the kinetic energy of an electron if it were bound in the nucleus. Answer: ∼ 200 MeV for R ∼ 1 fm...

Sorry if this question has already been asked many times, but I found no answer after a quick search. Have already made an experimental test of the Heisenberg's inequalities: \Delta p \Delta x \geq \hbar I'm quite sure our instruments' imprecision are larger than Planck's constant, but I...

Homework Statement 1) I try to understand the lorentzian lineshape and relate to the gaussian graph but i don't know what is the difference. 2) Uncertainty principle- if it's related to the lorentzian lineshape it will give the information about the lifetime in the well and the width of...

I was reading about how Heisenberg found out that it is "impossible to determine simultaneously with unlimited precision the position and momentum of a particle" (Serway/Moss/Moyer, 174) \Delta p\Delta x \geqh/2 (where h is plank's constant over 2pi.) My question is why is this true? I...

I was reading about how Heisenberg found out that it is "impossible to determine simultaneously with unlimited precision the position and momentum of a particle" (Serway/Moss/Moyer, 174)My question is why is this true? I read that it had something to do with the large wavenumbers \Deltak, but...

So I'm working on the proof of the generalized uncertainty principle and there is a step that I'm not fully understanding. There is a line were it says that for any complex number we can write the inequality as [Re(z)]^2 + [Im(z)]^2 >/ [Im(z)]^2. why are we able to get rid of the real part on...

Homework Statement Electrons in atoms are known to have energies in the range of a few eV. Show that the uncertainty principle allows electrons of this energy to be confined in a region the size of an atom (0.1 nm) Homework Equations \Deltax\Deltap \geq h bar / 2 \DeltaE\Deltat \geq...

Homework Statement 18. A ball of mass 50 g moves with a speed of 30 m/s. If its speed is measured to an accuracy of 0.1%, what is the minimum uncertainty in its position? 19. A proton has a kinetic energy of 1.0 MeV. If its momentum is measured with an uncertainty of 5.0%, what is the...

I have read that the time dependent wavefunction is related to the Fourier transform of the wavefunction for the angular wavenumber like so \bar{\psi}(k,t) = \frac{1}{\sqrt{2\pi}}\int \psi(x,t)e^{-ikx}dx Can anyone explain why it is relevant to take the Fourier transform of the...

Hi guys, I earned that \Delta E \Delta t \gtrapprox \frac{\hbar}{2} But one thing that's really strange is, according to Planck's assumption on black-body radiation problem, it just say that energy of each osciliator can be written as E = nhf where n is an integer. (I hope...

1. The problem is based uponYukawa's original prediction for pion mass-energy. suppose the force between nucleons is due to the emission of a particle mass m from one nucleon and the absorption by another. given the range of the nuclear force is R=(1.4)\times10^{-15} use \DeltaE\Deltat...

Scientists have reportedly been able to transport atoms and molecules as much as 1800 feet. Could the same be done for humans, or would the Heisenberg Uncertainty Principle ultimately make it impossible?

Homework Statement Hey everyone. I've been trying to figure out these two problems for a few hours now to no luck. I really have no idea where to start. Hopefully, someone can help me out. 1) a) How much time is needed to measure the kinetic energy of an electron whose speed is 10.0 m/s with...

Hi,all, I am wondering, momentum can expressed as energy, so: dxdP can expresses as dxdE ? then position, momentum, energy,time are all related, and they all form uncertainty relations?? in the view of commute the operators, all these four operators can NOT commute?? where am I...

Hi,all, can anyone help to understand how uncertainty principle consist with energy conservation? dEdt >= h/2, then in a short time interval, the energy can be really large, even the previous state has lower energy? I can't really understand this.. say, particle A appeared at t=0 (at...

We can apply Heisenberg's uncertainty principle (between energy and time) to the Big Bang. In early universe, at moment t, no energies below h/t were possible in principle because there was not enough time for such low energies to manifest. That minimal energy defines a minimal temparature...

In regards to watching this video: If the distance between the light source & board which the light is being displayed on was far apart like 100m. & you were the only person around observing the results right near the display. Then would the beam still be spread out? Confused with this...

Is the Heisenberg Uncertainty Principle as statement about the state of a particle or only a statement about what can be observed about a particle?

An atom represents a region about 1.7 10-10 m wide in which an electron is confined. Use the Heisenberg uncertainty principle to estimate the minimum kinetic energy of the electron, expressing your result in electron-volts (eV). So I got the problem right when I analyzed the atom as a 1 d...

assuming that Delta p = aprroxiamtely p, how can the uncertainty principle, be manipulated in order to achieve the speed of an alpha particle trapped in a nucleus of just say uranium 238 with proton number 92 ? or any other nucleus...what is the main manipulation steps of the formula?would...

Hi all Please take a look here (just read the first paragraph): http://hyperphysics.phy-astr.gsu.edu/Hbase/quantum/parlif.html I am a little uncertain of why it is that we equal the spread in time ∆t to the lifetime of the excited state (in the above link they denote the lifetime by Γ)...

In thinking about QM, I was wondering if anyone could comment on this? Back in prehistoric times, I did research using bubble chambers. In a bubble chamber, you see a number of curved (because of the magnetic field the chamber is imbedded in) tracks corresponding to different particles...

Why is there a time energy uncertainty principle? I thought that uncertainty was a characteristic of two operators not commuting. There is no operator for time, which, as I am constantly reminded, is a parameter of evolution, not an observable.

Homework Statement The Heisenberg uncertainty principle can be derived by operator algebra , as follows. Consider a one-dimensional system, with position and momentum observables x and p. The goal is to find the minimum possible uncertainties in the predicted values of the position and momentum...

a 1.0 micrometer diameter dust particles (mass 1.0x10^-15kg) in a vacuum chamber pass through a hole (diameter assumed to be exactly that of particle) onto a detection plate 1.0m below. By how much does the diameter of the circle increase Homework Equations This is clearly a Heisenberg...

Homework Statement A mosquito of mass .15mg is found to be flying at a speed of 50 cm/s within an uncertainly of .5 mm/s. a) How precisely can it's position be known? Homework Equations Delta p * Delta x = h bar / 2 p = mv The Attempt at a Solution I look at problem...

I am trying to really, truly understand the uncertainty principle. I have done a lot of reading and self-study and listening to lectures online. I feel I'm getting closer, but would appreciate some help in directing my further efforts. Here is my horrible patchwork understanding thus far...

Hi, I just finished taking my first look at some quantum physics material and need some confirmation on a point which was not clear within the material, which I think will be pretty easy for you to answer. The measuring of a particles position/momentum: If in theory a piece of apparatus...

I'm currently in an intro chemistry class and a lot of the material is review from the multiple physics classes I have taken. Most of it comes back easily, including how to use the uncertainty principle to solve the small array of homework questions thrown at me but when trying to grasp a deeper...

Hi... I have a little question I've been wondering. In my physics book (Young & Freedman - University Physics) the "Uncertainty Principle" is given as: \[\Delta x\Delta {{p}_{x}}\ge \hbar \] But on Wikipedia, and my math-instructor tells me the same, it's given by: \[\Delta x\Delta...

Homework Statement http://img340.imageshack.us/img340/3249/question.jpg Homework Equations P=h/lambda E=p^2/2m The Attempt at a Solution Well, I calculated P using a wavelength of .1 femtometer. Then I plugged it into the energy equation. However, I got 1.5e14 eV, while the...

Hi, I have a problem with the uncertainty principle. The way I understand it, Heisenberg used ideas from classical mechanics and the concept of wave/particle duality to show a contradiction in classical mechanics, i.e. that it is impossible to know with exact precision both the momentum and...