Uncertainty principle Definition and 528 Threads

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...

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...