Uncertainty Definition and 1000 Threads

I'm trying to get my head round this. I don't see why our inability to measure the world around us means that at the quantum level things must be random. I understand that measuring momentum of a particle to a high degree of accuracy means losing accuracy in it known position. But I don't...

Uncertainty analysis in aerofoil! Help! Homework Statement Wind tunnel experiment using a constant velocity to determine Cl, Cd and Cm at different angle of attack (-5, 0, 5, 10, 15) of a symmetric airfoil. Error analysis of the experimental investigation to asses uncertainties in Cd, Cl, Cm...

]How can H.U.P be used to explain the following : (i) The non-existence of the electron in the nucleus. (ii) The existence of protons, neutrons and alpha particle. (iii) The existence of finite zero point energy. (iV) The binding energy of an electron in an Hydrogen atom is of the order of 15...

I had this https://www.physicsforums.com/showthread.php?p=3200140#post3200140", which I posted on PF. I got the answer, but then I started thinking more about it and have some theoretical questions. If you did have this particle of mass m in a box of length L, which you are trying to stop...

How do time-energy uncertainty and special relativity's rules about observers seeing time different for each other interact? Heisenberg's uncertainty principal applies to time and energy: a system existing for a short duration of time has more uncertainty in its energy than one that exists...

hello I have some questions which I was struggeling with 1. Is percentage error the same as percentage uncertainty? Because percentage error is a measurement of accuracy and is percentage uncertainty also a measure of accuracy? 2. How do percentage uncertainty and percentage difference affect...

I was reading that a meter is the length of the path traveled by light in a vacuum in 1⁄299,792,458 of a second. So the speed of light is exactly 299,792,458 m/s. I am wondering what is the uncertainty in our most accurate measurement of the speed of light. For example say I had a machine...

Hello I was given following homework question. 2 gradients are given. gradient1 of the line is 0.503 gradient2 of the line intersecting the line above is 0.167. Find out the percentage uncertainty in the gradient. i thought you have to do (0.503-0.167)/0.503 is that right?Please help thanks...

Hi folks, I do read some of the interesting post on this forum particularly the discussions on the concept of uncertainty principle ie the more you know about the particle position the less you know about its momentum etc etc I am a complete novice and am trying to get the big picture here...

Homework Statement So I have this homework question and the answer that was given to me to check the answer that I have does not match with my answer. The question I have to complete is shown below: The answer given to me is D, 6.6eV Homework Equations \Deltat\DeltaE = h/2...

Homework Statement I'm looking at an electron-in-a-box with walls at x=0 and x=L; I want to calculate the uncertainty (delta p) in the measurement of its momentum: sqrt(<p^2>−<p>^2) for its nth excited state. Homework Equations The normalized wave function: psi_n(x)=sqrt(2/L)*sin(n*pi*x/L)...

We all know that our universe is headed towards a heat death with maximum entropy and useless energy. However, we know that a vacuum of space will always have energy greater than its local minimum (potential well) due to the uncertainty principle. There must always be random fluctuations...

Two observers A and B are in relative motion with a constant velocity[for example, along the x-x' direction].If A knows the the position of B accurately , the motion of B gets enormously uncertain[and vice verse] in his calculations/considerations.How is he going to derive the Lorentz...

We all know that you can supposedly never know the exact position and momentum of a particle, because the very act of measuring disturbs it. Now, why can't we have two particles that start out and evolve the same exact way but separately and, using one of them as a dummy, perturb it, extract...

Homework Statement Find the uncertainty for pi using (a) the formulas (b) calculusHomework Equations \pi = (4/D^{2})(hw - m/(PL)) Uncertainty formulas: for products and quotients: Z = XY \deltaZ/Z = \deltaX/X + \deltaY/Y for differences: Z = X - Y \deltaZ/Z = \deltaX/(|X - Y|) +...

Well first off, I am confused about what the book says earlier and what the actual answers are in the back of the book on homework problems. I thought I understood the book, but it seems like I don't. The book has: "Consider a particle whose location is known within a width of L along the x...

Homework Statement The value of the speed of sound obtained in an experiment is 327.76 ms-1. The result has an uncertainty of +-3% of the result. Which one of the following values is expressed to the correct number of significant figures? (A) 327m-1 (B)327.8ms-1 (c)328ms-1 (D)330ms-s...

4. A rectangular concrete floor is measured. Its length is (4.25 ± 0.05) m and width is (1.80 ± 0.05) m. Determine: b) the area and its uncertainty. This was the solution. However I got 6.65 x 10^2 as my absolute uncertainty. My questions are: 2. When finding the final uncertainty that...

Homework Statement I need to calculate the uncertainty for the velocity v_1=(cart length)/t_1. The cart length is constant. Homework Equations That is what I am not sure about. I need to use the rule "dividing by a constant" to find the uncertainty. Is that result q=B/x ,where B is...

To be honest, this is straight up advertising, but I think it'll be helpful to a lot of people. My friend has made an Uncertainty calculator app for the iPhone (android coming soon), and it has saved me tons of time. So I just want to support him. Here are the links and screen shots...

I'm in the process of doing a quantum physics lab and am having a bit of trouble with uncertainty. The specific things going on in the lab aren't relevant, I don't think, only the general procedure of my calculation. Also, I'm not certain where this question should be asked, so I decided to put...

Homework Statement A baseball player friend of yours wants to determine his pitching speed. You have him stand on a ledge and throw the ball horizontally so that his release point is 3.6 m above the ground. The ball lands 29.0 m away. a. What is his pitching speed? b. As you think about...

Does anyone know if there is an online english translation of Heisenberg's paper on uncertainty "über den anschaulichen Inhalt der quantentheoretischen Kinematik und Mechanik" Z. für Phys. 43, 1927. I haven't been able to find it so far, all I can find is one's in German...

Homework Statement 4 glasses of liquid must be transfferred into a beaker that has a cylinder shape without any markings. The teacher says that the glass will hold 250mL, but the uncertainty was 10mL in which this was determined. The radius and the height of the beaker was measured within an...

Homework Statement Drivers that come to a stop leave different amount of gaps between their car and the car in front. It was found that the average gap was 1.45m, but as the values varied, the uncertainty was 25cm. It was also reported that the car is 5.1 ± 0.5m in average. What is the range...

I have a few questions regarding how/when to use which uncertainty principle formulas. I am not sure of the difference between them. I've checked my book and wiki and neither really helped. Here are the formulas in question. \Delta p \Delta x \approx \hbar \Delta p \Delta x \geq...

The Uncertainty Principle is an inequality relation but while its application, only the equality is considered. For example - to calculate the Mass/Energy of a particle produced during an interaction, the Life Time of the particle is used to divide the Constant (h/2). But in principle the...

Homework Statement An electron is conned inside a cubic region of size an atomic radius L = 0.5 nm. Homework Equations What is the uncertainty in the momentum p of the electron? Remember that \Delta p \Delta x \approx h. The Attempt at a Solution I am confused when to use \Delta p \Delta x...

Homework Statement Perform the calculation and report answer in proper scientific notation with absolute uncertainty 73.936(+ 0.19%) / [(0.00455+ 0.00096) + (0.011889(+0.73%))] Homework Equations Addition/Subtraction: Absolute uncertainty = square root(uncertainty1 + uncertainty2)...

I had a thought going in my head today about the uncertainty principle. Forgive me if it sounds too silly. Consider an electron in motion. Now, suppose that I'm measuring it's position with infinite accuracy. So, by the uncertainty principle, it's velocity is blurry. But what if I measure the...

I am trying to understand fully the concept of this principle. But this uncertainty stuff confuses me. Can someone give me the link, or some material so I can work mathematics behind this mechanism. Its not that principle it self is the problem, I have glimpse what's going on, but the...

Hey there, I have a problem to do, in which I need to determine the acceleration of an object and the uncertainty of the acceleration. The position vs. time equation is given by: s(t) = 0.205t2 + 0.3001t Therefore, after differentiation, I can state the the velocity vs. time equation...

Analogous to the uncertainty relation ΔpΔx > h/4π, there is an uncertainty relation for the time and energy, ΔEΔt > h/4π that stems from the methods usually used to measure the energy. The uncertainty in the time, Δt, can be interpreted as a lifetime. The excited state of an atom responsible...

Homework Statement This is from a laboratory exercise. I was asked to measure the time it took for a pendulum to cover 3 periods. I repeated this 25 times, to get 25 measurements for as many trials. I also calculated the standard deviation from the measured data (calculated for different...

Determine the absolute uncertainty of the prism's volume. The uncertainty of each measurement is +/- 0.5mm. The length of the prism is 142mm, width is 86mm and the height is 151mm. Thank you!

Hi folks, I am new to physics forums , an engineer by profession, I have newly developed some interest for pure physics, can someone please enlighten me on the violation of energy conservation by the time energy UP? The way I understand it the principle only puts a LOWER bound. Is...

What's Really so "Quantum" About Heisenberg's Uncertainty? I've never really understood what was so interesting and strange about Heisenberg's Uncertainty (or Robertson's Inequalities). If we take as axiom that particles exist as wave functions that satisfy schrodinger's equation then what is...

Homework Statement Using the uncertainty principle, estimate the minimum energy in electron volts of an electron confined to a spherical region of radius 0.1nm. Homework Equations delta-x * delta-p = h-bar / lamda delta-y * delta-p = h-bar / lamda delta-z * delta-p = h-bar /...

Given the state and an operator I know the uncertainty of this operator can be calculated via (see next post latex is being weird, sorry)

I am new to XRD and want to know the best way to measure uncertainty. Any help would be greatly appreciated.

I'm working through John Taylor's An Introduction to Error Analysis and so far this is the only problem I haven't been able to solve. I was hoping someone could lend me some insight. The problem asks you to use error propagation to verify that the uncertainties in A and B for a line of the...

I am looking at the paper "The uncertainty principle in the presence of quantum memory" by Berta and others. It states that if Bob maximally entangles a particle P with a quantum memory M then he can beat the bound of the uncertainty principle on P. The argument is that, if Bob gives P to...

If buckyballs display uncertainty in the double slit experiment, shouldn't iodine gas molecules as well? An I2 molecule is certainly less massive than a buckyball. Yet why can we see I2 gas as a purple haze? I can see it, almost in the same way I can see my pencil, which has a very small...

Hi together ... In many textbooks on particle physics i encounter - at least in my mind - a misuse of the Heisenberg uncertainty principle. For completeness we talk about \Delta p \Delta x \geq \hbar/2 For example they state that the size of an atom is of the order of a few Angstroms...

Whenever I hear the Uncertainty Principle used, It's always to talk about how a particles' momentum can only be known to a certain range if it's position is known too precisely, and in problems I've encountered, or vice-versa. In problems I've encountered, often times I'll be asked to find the...

For the ground state of a particle moving freely in a one-dimentional box 0\leqx\leqL with rigid reflecting end-points, the uncertainty product (del x)(del p) is 1 h/2 2 sqrt{2}h 3 >h/2 4 h/sqrt{3} I used (del x)^2 =<x^2>-<x>^2 and (del p)^2 =<p^2>-<p>^2 Using the wavefunction of...

I am having trouble understanding (not for homework) what a wave packet is in terms of the correspondence of the idea of a wave packet to a "point like" particle. I'd like to focus on the 1d wave packet ultimately, but in order to describe my consternation -- let me detour to a well defined...

Why do we use significant figures in calculations instead of the rate of Uncertainty? (2,5\pm0,4000)*4,000=(10\pm1,6). The number 2,5 has 2 significant figures, which is the same as we will write in the answer, while it should be only one significant figure in the answer if we take the rate of...

I think this is right, but could someone confirm (or deny) this for me? While a particle like an electron - or a finite set of particles for that matter - is represented by a single normed vector in Hilbert space which is acted on by operators such as ones for energy, position and momentum...

in Heisenbergs uncertainty principle, how do you know when to use hbar, h, h/2 or hbar/2? thanks