Uncertainty principle Definition and 541 Threads

Hello Folks! Though I have written my own paper (http://arxiv.org/abs/math.DG/0605709) , I am still a novice in Standard Model. Therefore, I have some questions for experts. The modules squares of the fermion wave functions are interpreted as the probability densities for the particles to...

The Heisenberg uncertainty principle says that h-bar/2 <= dE * dt. Let's say we have this device that emitted very low energy radio waves. Does that mean there'd be a significant probability of these photons traveling faster than light?

Most popular or elementary textbook level expositions advance the following physical argument in favor of the uncertainty principle: In order to observe a state we must disturb it. Thus we have changed the state by our very act of observation and uncertainty creeps in. Now this explanation...

Hi, I was wondering about the following question. Does Heisenberg's Energy-Time uncertainty inequality (ΔE.Δt=>h/2) imply non-conservation of energy? I mean, if the total energy of the system fluctuates, then how can the energy be conserved? Does the COnservation of Energy so fundamental to...

Can someone explain why the compton wavelength and event horizon are used to determine the uncertainty in what we can see if we were to look back in time to the big bang. (We can only see back to 10^-43 seconds after the big bang.) Here's a website that derives this time (Planck time)...

The energy of a certain nuclear state can be measured with an uncertainty 1 eV. What is the minimum lifetime of this state? I used (delta_E)(delta_t)=h/(4*pi) and solved for delta_t and got it wrong. Any ideas? Thanks.

I'm having a little trouble with my textbook's explanation. This is regarding the energy - time variation of the uncertainty principle; very basic stuff, so I hope helping me out won't take too much. Let me quote exactly: "... the energy conservation can appear to be violated by an amount...

I am having trouble getting going on this problem and I'm hoping someone can help get me started. I have no idea how to do solve this. Originally I thought about using Heisenberg's uncertainty principle and setting delta x = 1 m. Yet I don't see how the uncertainty in that direction is...

Hi, I try to understand the proof for the uncertainty principle for two Hermitian operators A and B in a Hilbert space. My questions are rather general so you don't need to know the specific proof. The first thing I couldn't get into my head was the definition of uncertainty (\Delta...

question is: use the uncertainty principle to show that if an electron were confined inside and atomic nucleus, diameter of 2 x 10^{-15}m, it would have to be moving relativistically i.e. more than 0.1c. what i have done is the following: \Delta x \Delta p = \frac{\hbar}{2} then i set...

Using the uncertainty principle for energy and time, estimate the range of the Strong interaction if it is due to the exchange of a pion with rest mass 140GeV (Take the value of h as 4.14x10^-21MeV s) Now I know that Delta T x Delta E is > or = to hbar and that I want DeltaX as a solution. But...

Would it be correct to conclude from the Uncertainty Principle that the Newtonian mechanics of being able to exactly determine the velocity of a particle from its displacement (and vice versa) through differential equations is only an approximation? Many fundalmental things in the Universe is...

I have read the theory about uncertainty and cannot quite grasp it. Why is it that we cannot measure the speed of an electron and its location at the same time? As I understand it, the reason for probablility waves is because we cannot measure speed without disrupting where the electron is, or...

GIVEN: 1. The more accurately you determine a particle's position, the less you know about its momentum, and vice versa. (Heisenberg Uncertainty Principle) 2. Momentum is defined as mass times velocity. 3. Velocity is defined as change in position over time. 4. The rest mass of a particle...

I have a question about an example in my physics notes. It considers Nitrogen at room temperature and calculates p*r and finds this to be greater than h-bar and so it is consistent with the uncertainty principle: p*r = 2.4*10^-26 > hbar = 1*10^-27 It says at room temperature the momentum...

The Heisenberg Uncertainty Principle tells us that while it is possible to measure the position and velocity with reasonable accuracy, we cannot measure both an atom's position and velocity at the same time. The reason for this is simple. For instance, to find the position of an atom, we must...

a problem i had recently. I've always thought of the uncertainty principle as if you understand position you less understand velocity and vise versa. the model i know is that to know the exact poition of a particle you shine a light wave on it, the more accurate u want the position the higher...

The Heisenberg Uncertainty Principle states that both the exact (as near as we can get to thusfar) position AND momentum of a particle cannot be obtained because in learning its exact position we alter its momentum and vice versa. Does this mean we only have rough measurements of particles...

hey, I am really confused with this problem, i have tried to solve it for a while now but i can't seem to get it, i really don't even know where to start with it. In a TV picture tube the accelerating voltage is V, and the electron beam passes through an aperture with a diameter of Delta_y...

Is there any mathematical or physical proof or derivation of Heisenberg's Uncertainty principle out there? Can someone send me a link to one or provide a proof if it isn't too complicated? I know that in quantum mechanics if two operators don't commute then we can't measure both of these...

I'm wondering if someone could tell me what would be the result of the following thought experiment, to help answer a simple question I have about the Heisenberg Uncertainty Principle: (I am just an educated layman trying to figure it all out- hopefully my thought experiment isn't complete...

Heisenberg Uncertainty Principle - h/(4.Pi) versus h/(2.Pi) What's the reason behind the factor 2 in the way some books/papers present Heisenberg Uncertainty Principle? h/(4.Pi) versus h/(2.Pi) When in history did this discrepancy arise and who was responsible for that? Ultimately, which...

Recently I had a discussion with friends about impact of H.U.P. on some biological functions. We had disagreement, about uncertainty of position of ion, say in neuron connected to another one by synapse, as a consequence of HUP, point was that if there is some uncertainty in position of ion or...

uncertainty in Heisenbergs uncertainty principle (urgent) This might be a stupid question, but i seem to find different versions of this the more i look. I have a big exam tomorrow, and i have a slight problem. The thing is that our textbook says that Heisenberg's uncertainty principle is dx x...

First of all: I'm sorry if this question has been asked before. I tried a search, but couldn't find anything. So, the uncertainty principle prohibites anyone from knowing the exact location and velocity of a particle... If there was a God, wouldn't he/she have to know the exact location and...

anyone happen to know how to estimate the ground state energy of a vee-box using the uncertainty principle?

I have a fundamental question regarding the uncertainty principle (position and momentum). This principle states that it is impossible simultaneously to know both position and momentum with arbitrarily good precision - even in principle. Now, what does "know" mean? No one can prevent you from...

Hi, What is a good way to explain the uncertainty principle to a new freshman who has never had any quantum mechanics? That is, in plain English and without mentioning momentum space or anything.

For a particle-in-a-box it can be shown that the possible energies are given by E_n = \frac{n^2h^2}{8mL^2} where L is the length of the box. The corresponding momentum are given by: p_n = \frac{nh}{2L} I don't think it's a problem that the energy has a definite value ( \Delta E =...

I read somewhere that one of the explanations for an electron not spiraling into the nucleus is due to the uncertainty principle. If an electron falls into the nucleus both its position and velocity will be certain. How is that possible? Does the nucleus have both certainty in position and...

As you all know there is this Heisenberg's Uncercainty Principle. Way I see it, the uncertainty principle relates to the measurement of both position and momentum of the particle/electron/etc-small-subatomic-anything at the same time. Among other things like energy-time, energy-halftime, etc...

In my eng. phys II class my prof. today was telling us about how in a bb experiment if you shoot it through a small slit (very small) and shoot let's say 20 bb's in a row and then look at where they embedd themselves past the slit if you have let's say piece of cardboard they bbs even if all...

I've got a few questions about the uncertainty principle and I'm new to more advanced physics. So from what I understand about the uncertainty principle is, Ok, I've got a particle. And say, I want to know the exact location of the particle. And the wave amplitude is highest closest at its...

If I use E x t = h bar and put t = age of universe in seconds = 10^ 18 seconds, E x 10^18 = 10 ^ -34 gives E = 10^ -52 Joules. So if an oscillator of some sort in the early universe absorbed a photon, and emitted the energy of that photon today, there would be an uncertainty in the...

Can anyone help me on this?? In a contest to drop a marble with mass 30 g from the roof of a building onto a small target 50 m below. From uncertainty principle considerations, what is the typical distance by which you will miss the target, given that you aim with the highest possible...

I'm a newcomer to physics (know of any good beginner forums?) and was wondering why the uncertainty principle is true.

WE all know that: dE dt >= h/2pi or dS dt >= h/2pi But... mathematically, what does that mean?

At which scale in length terms does the Heisenburg Uncertainty Principle kick in for Stringtheory? In the string vibration for Gravitational interactions, as the scale is condensed, surely this would have a 'bigger' Uncertainty in strings that split off due to their proximity in scale...

Hi, my physics tutor was explaining to the AS physics class about Heisenberg's Uncertainty Principle, and having never been told about it in any great detail, I am intrigued. I vaguely understand part of it but i would be grateful if someone could explain the other part, which as far as i know...

The Heisenberg Uncertainty Principle --> Life is uncertain The Heisenberg Uncertainty Principle --> Life is uncertain. Eat dessert FIRST!

Can someone inform me a bit on the background of this problem, it's experimental testing and it's implications? If I have it right, it involves two particles which are involved in a singular event. If you measure the momentum of the first particle, you not only create uncertainty in it's...