Uncertainty Definition and 1000 Threads

Hi, I am unsure of what uncertainty to get, so here is my full question: I used the CRO for an experiment, and since what I need is frequency, I read the period, so for the uncertainty of the period, it is the smallest division divided by two. So if my uncertainty for period is 0.001s, then what...

Hi everyone, The equation is one we have been given to calculate the rotational speed of the sun for different latitudes. phi = average latitude. This shouldn't be a problem for me, but for some reason I just can't trust my error calcs. We are given : A = 14.713 ± 0.0491◦/d B = −2.396 ±...

I have a measurement with uncertainties for two years. Say Year 1 Rain : 100mm(80-120mm) Year 2 Rain : 120mm(103-131mm). Now I get the percentage change in rain in Year 2 w.r.t Year 1 as 20%. Is there a way to get the uncertainty associated with this percentage change?

What causes quantum uncertainty? My friend who's working for Apknite says that detectors are not the cause of wave collapse, because you are measuring something that isn't remaining in the same state.

So the only part of this question I am having an issue with is the uncertainty part in part e). I have included the whole question as reference. So to derive the uncertainty in ff I used the uncertainty equation outlined above but the issue is that when I propagate the uncertainty I end up with...

In Quanta Magazine there is article on this link...

I have a bit of confusion regarding the application of the uncertainty principle in the context of experiments. If a detector allows you to measure a particle's path through said detector, does that mean that you know a particle's position at all points in time, and are able to work out its...

I have been trying to see if my understanding of uncertainty principle is right. So I thought consider a circle. for this augment we will look at its diameter and it circumference. Suppose you get a length of string and make a exact measure of the circles circumference using this length of...

I am not too knowledgeable about QM, so please forgive me if this is a dumb question. I have outlined below an experiment setup for which Heisenberg's uncertainty principle seems not to apply: Imagine a particle for which we wish to collect the exact position and velocity. We have a detector d1...

I thought that since he micrometer is to 2 significant figures (0.35 and 0.01mm) that the final answer should also be to 2 sig.figs, thus answer A. But the final answer is C, 3%. Can someone explain why?

Apologies in advance if my understandings are simply incorrect. As I understand it, there is a limit to what can be known about both a particle's position and momentum, and in some interpretations this is because there is no position or momentum until measurement only a probability. What I am...

I am thinking of doing the same thing (summing up all the uncertainties that contribute to U(E) in the example) for the task, so summing up all the fractional uncertainties that contribute to U(Q). But the problem is unlike energy in the example, I'm not sure what's the contributors that lead to...

I tried to find examples on the internet but I am still confused.

The main role in quantum gravity can be played by the uncertainty principle , where is the gravitational radius, is the radial coordinate, is the Planck length. This uncertainty principle is another form of Heisenberg's uncertainty principle between momentum and coordinate as applied to the...

Hi all. Awesome site! Just wondering if anyone can answer my question: If the Sextans galaxies are inside the group's zero velocity surface, why is there uncertainty over whether they're part of the group?

If you calculate the uncertainty of a scalar field in the vacuum state, i.e. ##\langle0\left| \phi^2\right|0\rangle##, you get a divergent integral that comes out to something like $$\frac{1}{4\pi^2}\int_0^\Lambda \frac{k^2 dk}{\sqrt{{m^2}+{k^2}}}$$ Where ##\Lambda## is some momentum cutoff...

Hi For 2 Hermitian operators A and B using the Cauchy-Schwarz inequality and assuming the expectation values of A and B are zero I get (ΔA)2(ΔB)2 ≥ (1/4)|<(AB+BA)>|2 + (1/4)|<(AB-BA)>|2 Now both terms on the RHS are positive so why is this inequality usually just written with only the...

Homework Statement I need to work out the errors of my corrected apparent magnitudes. The Colour Excess is 0.36 with uncertainty = 0.01 The star was observed in two wavebands. r-band = 2.285 g-band = 3.303 The 2.285 and 3.303 are the ratios R_V for the SDSS (Sloan digital sky servery) r and...

Homework Statement I have a star that has an apparent magnitude of 13.73 with uncertainty of 0.03303 It's distance Modulus is 13.9967 so it's absolute magnitude is -0.26 The distance is 6300 parsecsHomework Equations [/B] The uncertainty on log10(d) is given by Δ(log10)≈0.4343 Δd/d ΔQ) =...

Homework Statement This conversion factor 1m = 39.3701 inches was used, when measuring a tape that had inches on it to a full meter. The measuring tape increased by 0.0625 inch increments, so the 1 meter (39.3701) was estimated to be in between the 39.3125 and 39.3750 on the actual measuring...

As someone who is interested in astrophysics, I always get emphasized on the importance of knowing statistics and error analysis in results of a calculation. However when I read about real physics papers, I never see any numerical solutions, just equations that demonstrate phenomena. I know that...

Homework Statement Calculate the circumference (including uncertainty) of a circle whose measured radius is r=7.3 ± 0.2cm. 2.Relevant equations & 3.The attempt at a solution - Circumference of circle --> C = 2πr = 2π7.3 = 45.87 cm - Exact constant error propagation --> z =...

Homework Statement The problem asks to convert time in minutes to time in hours, and to also calculate the uncertainty for the time in hours.Specifically 10 minutes +/- 0.2min being converted to hours with uncertainty. 2. Homework Equations & 3.The attempt at a solution conversion of time...

I was reading a book which had some comments on EPR paper (Einstein, Podolsky, Rosen - 1935) like following: In Newton's physics, when two identical billiard balls hit each other head-on, bouncing off in opposite direction, knowing one ball's position and speed will also indicate other ball's...

Homework Statement Correctly present the table of information. The values in the table are deliberately in a wrong format. The calculated Re values have been analysed to have an uncertainty of ± 0.4% and the calculated f values an uncertainty of ± 0.1%. Homework EquationsThe Attempt at a...

I have come across a paper where it is stated that if the infinity assumption in the FT is removed, the uncertainty doesn't hold. Is this a sensible argument? Thank you.

I state the following study and then expose my doubt at the end. MY SYSTEM A free particle (absence of forces) on one-dimensional space (X axis). INITIAL STATE At t=0 the wave function is a Gaussian wave packet NOT normalizet centered in ##x_{0}## and with standard deviation ##\sigma##...

I'm a hobbyist physicist and I just started studying QM through watching Leonard Susskind's lectures on the Stanford Youtube channel. I get the idea of it being impossible to precisely know both a subatomic particle's position and momentum, but is this actually a physical limitation? Or is it...

There are two aspects of uncertainty (a) how far different from the situation where all possibilities are of equal probability (b) how spread out the values are. In discussions about (Shannon) entropy and information, the first aspect is emphasized, whereas in discussions about the standard...

Hello, In Griffiths (2nd edition) pgs 110-111 - deriving the uncertainty principle I have 2 questions 1) I am stuck on a point ... (h = ^ hat ) <f | g > = < ( Ah - <A>) ψ | ( Bh - <B>) ψ > = <Ψ | ( Ah - <A>) ( Bh - <B>) Ψ> FOIL = <ψ | AhBh ψ> - <B><ψ | Ah ψ> - <A>< ψ | Bh ψ> +...

To summarize, my current understanding of how Heisenberg's uncertainty principal works suggests that there would be a contradiction (somewhere down the line) with any way that it applies to (or doesn't apply to) photons, due to the fact that they must always travel the speed of light. I...

I'm doing a lab report from electronic spectrum of iodine. I did Birge-Sponer plot from my data. Excel gave it to me a slope y = -2,0698x+133,34. From regression analysis I get uncertainties for slope and intercept. Slope: ##-2,069761731 \pm 0,075075941## Intercept: ##133,3385857 \pm...

heisenberg uncertainty principle ## Δx Δp ≥ ħ## where ##Δx = \sqrt{<\hat{x}^2>-<\hat{x}>^2}## ##Δp = \sqrt{<\hat{p}^2>-<\hat{p}>^2}## I don't know. Why ##Δx## equal to ## \sqrt{<\hat{x}^2>-<\hat{x}>^2} ## and ## Δp ## equal to ## \sqrt{<\hat{p}^2>-<\hat{p}>^2} ## What can I find out about...

Homework Statement Watching an object fall, along a ruler, using a stopwatch to take the time from when the object flies passed the upper part of the ruler, and again when it hits the floor (bottom of the ruler) Homework EquationsThe Attempt at a Solution My friend is doing introductory...

Hello everybody, I need a help, primarly a confirmation about my reasoning. I have data from a MonteCarlo simulation of collisions between particles at LHC (made with Madgraph). I have plotted some variables, for example the angle between two final leptons. Then I have normalized the plot to a...

The uncertainty principle says that you can't know position and velocity of particle at the same time. So particular we can not say that the particle is at rest at some point because then we would know it is not moving and we would know exactly where it is. So my question is if we send the...

Homework Statement Given the kinematics equation v2 = u2 + 2as, find the uncertainty Δv. Given: Values of a, s, u, and their associated uncertainties. Homework Equations v2 = u2 + 2as The Attempt at a Solution I'm aware of the rules for uncertainty propagation, but what do I do in this case...

Instead of just taking one measurement of the particle, you take a 2nd measurement in addition thereby gathering more information about the particle then the uncertainty principle allows?It would be possible to extend out to an arbitrary number of follow-on measurements thereby measuring...

Hi everybody, my question is a curiosity on the (generalized) Heisenberg principle: ## \sigma_{x}\sigma_{p} \geq \frac{\hbar}{2},## where ##x,p## are the usual quantum operators and ##\hbar## the Planck constant divided by ##2\pi##. If I understood correctly, Gaussian states that are solution...

Homework Statement For the ground state of a particle moving freely in a one-dimensional box 0≤x≤L with rigid reflecting end points, the uncertainity product (Δx)(Δp) is (A) h/2 (B) h√2 (C) >h/2 (D) h/√3Homework Equations The uncertainity principle says that - (Δx)(Δp) ≥ ħ/2 Ground state energy...

Why is fractional uncertainty not affected by systematic error? For example à vernier calipers measures the diameter of a coin: (5.06+-0.04) mm Can taking more readings, say 6, and taking average, reduce fractional error?

Question: A distance R is measured to be 3.400 ± 0.007m. What is the absolute uncertainty in R^−2? Attempted solution: Relative uncertainty: 2* (0.007/3.4) = 4.11E-3; R^-2 = 3.4^-2 = 0.0865 m^-2; Absolute uncertainty = R^-2 * relative = 0.0865 * 4.11E-3 = 3E-4 m^-2; Any help would be greatly...

Hello, I was recently pondering on significant figures and uncertainty reminding myself that there is no perfect measurement: every measurement involves an error caused by the instrument and/or the operator. A measurement should be executed as many times as possible and not just once. The...

Homework Statement The duration of a laser pulse is 10^(-8) s. The uncertainty in its energy will be? Homework Equations ## \delta x \delta p=\frac{h}{2\pi}## The Attempt at a Solution speed of laser beam=c, duration is given so distance can be calculated exactly-shouldn't that mean delta...

There is something I seriously don't understand about uncertainty. Suppose there is an electric balance that reads 5.67g The limit of reading is 0.01g The greatest possible error is half of the limit of reading and is thus 0.005g By this logic, and assuming the very best possible situation, I...

This isn't a homework question, but instead a question about an example in a book I'm reading, in prep for next semester. As such using the posting template is a bit of a miss. Hope that can be forgiven. 1. Homework Statement I'm reading "An Introduction to Error Analysis" by John R Taylor...

Homework Statement Homework Equations The Attempt at a Solution it looks like I got too big numbers for the uncertainty

How do i suppose to determine the uncertainty for the slope of my Static friction against normal reaction graph? My data for static friction and normal force has the uncertainty of +/- 0.0001 The uncertainty is too small for me to draw airbox/bar in the graph to draw the max and min slope...

I have seen that the more a particle has a high energy, i.e ##E##, the more its lifetime is short, respecting so the uncertainty principle. But by the definition of this uncertainty principle : ##E\,\Delta t \geq \dfrac{\hbar}{2}##, I can write : ##\Delta t \geq \dfrac{\hbar}{2E}##, then...

Fitting data to a linear function (y=a0+a1*x) with least square gives the coefficients a0 and a1. I am having trouble with calculating the uncertainty of a0. I understand that the diagonal elements of the covariance matrix C is the square of the uncertainty of each coefficient if there are no...