Measurement Definition and 1000 Threads

This is a surface level question and I don't want to go into detail. Imagine an algorithm which when used with a sensor output gives the statistical moments of a variable in nature (for example mean and standard deviation of a variable). The sensor measures this once in a while (like once in a...

Is the accuracy of 10^-12 s achievable in measuring a neutrino's speed with current experiments? I have come across a number of papers stating the accuracy is in the order of nanoseconds. This is much lower accuracy than the measured speed of photons. I believe it is due to the difficulties in...

Two clocks with photo detectors are 100 kilometers apart at A and B. On the center of AB axis two light pulses are sent to the clocks , synchronizing them. Then a light signal is sent from A to B. The two stationary observers record the time from event at A to event at B. Is there a one way...

By analyzing 91,742 reported extra-galactic distances and their one sigma uncertainties for 14,560 galaxies, it was found that pairs of reported extra-galactic distances of the same galaxy differ from each other by 2.07 the reported uncertainties on average. In my opinion, this indicates that...

I first Normalise the wavefunction: $$ \Psi_N = A*\Psi, \textrm{ where } A = (\frac{1}{\sum {|a_n^{'}|^{2}}})^{1/2} $$ $$ \Psi_N = \frac{2}{7}\phi_1^Q+\frac{3}{7}\phi_2^Q+\frac{6}{7}\phi_3^Q $$ The Eigenstate Equation is: $$\hat{Q}\phi_n=q_n\phi_n$$ The eigenvalues are the set of possible...

Hello, I have a question about the measurement of a qubit in the computational basis. I would like to first state what I know so far and then ask my actual question at the end.What I know: Let's say we have a qubit in the general state of ##|\psi\rangle = \alpha|0\rangle + \beta|1\rangle##. Now...

[Mentor Note -- thread moved to the schoolwork forums from the technical forums] Summary:: I would like to understand how to calculate the error of a measurement provided by a measuring chain Hello to everyone, I'm going to explain the problem I would like to understand better. Thank you for...

hi, can anyone please give me the list of measurement we can do ON Feynman diagram? Like , branching ratio, cross-section etc

This method calculates surface tension based on force balance acting on the ring placed on the liquid surface: $$ F = G + \gamma L $$ where ##G## is weight of the ring, ##L## is wetted length of the ring which is equal to its circumference, ##F## is outer force of tensiometer acting on the ring...

We are working on new software for one of our measurement systems (written in Python). The new system is capable of measuring more devices simultaneously than before so keeping track of what we are doing is important; it will also be more automated. One of the things we want to implement is...

When I think about it my biggest issue with the interpretation of QT can be boiled down to this question. There are the axioms of measurement in QT, which have their limiting nature and claim to be the only way to extract information from a quantum system - but that is just a claim with enough...

I have done this question and gotten: Vmin = 4pi/3(19.18)^3=29555.2 V = 4pi/3(19.31)^3=30160.3 Vmax = 4pi/3(19.44)^3=30773.5 Uncertainty: {[30773.5-29555.2]/30160.3}x100=4.04% however this is wrong... Could someone please help me find out where I went wrong, or tell me if I went the wrong...

In the other thread of a similar name it was stated, and probably rightly so, that I wasn't using rigorous terminology or that I wasn't using them in a rigorous way. While I was making certain assumptions about the ability to interpret the 'jargon' I was using, it seemed to be a serious...

An electron beam with the spin state ## |\psi\rangle = \frac{1}{\sqrt{3}}|+\rangle+\sqrt{\frac{2}{3}}|-\rangle##, where ##\{|+\rangle,|-\rangle\}## is the eigenstates of ##\hat S_z##, passes through a Stern-Gerlach device with the magnetic field oriented in the ##Z## axis. Afterwards, it goes...

Continuing the discussion in the 'Assumptions of Bell's Theorem' thread, I'm hoping to explore the question of the location/position of the QM system prior to measurement. I may have some bias or underlying assumption that is affecting the conclusion that I am drawing and, by exploring this...

[Moderator's note: Spin-off posts from previous thread have been included in this new thread. Also, the OP's re-post of the scenario for discussion has been moved to this top post for clarity.] Yes. Physically, scales measure a force (and indirectly the energy) in their frame. Consider the...

Bostelmann, H., Fewster, C. J., & Ruep, M. H. (2021). Impossible measurements require impossible apparatus. Physical Review D, 103(2), 025017.

I need to work out the maximum thermal energy which can be stored within an area, and to do this I need to convert the specific heat capacity (which measures by mass) to measure instead by volume. Is there a common measurement term I can search for (in the same way as I might search "specific...

In the Schrödinger's cat thought experiment in its standard configuration, before the experimenter opens the box that contains the cat, has any relevant QM measurement been made by any objects involved in this instance of this experiment? My speculation/understanding: Yes, the cat knows (is...

Voltmeter is an instrument which measures electric potential difference between two points. When measuring electrode potential of some redox system (vs SHE for example), it is said that voltmeter reading contains sum of all potential differences present in a cell. This includes all...

I tried finding the distance but I later on got confused.

I need an epoxy/polycarbonate substrate diffuser film similar to this one https://www.luminitco.com/products/light-shaping-diffusers mirror and hard coated. I have two films sized 100x100mm each (3.93x3.93 inches or 5.57'' diagonal ). I have no idea what this will cost. What's the expected...

Couple questions here. 1. What do you think is the best source to read about decoherence, both from an intuitive/high level pov, but also with mathematical details. I'd partially read a recommended paper by Schlosshauer a while back, is that still the bible for this? 2. If probabilities in...

This is a very elementary question, from the beginnings of quantum mechanics. For simplicity, I refer to a finite case with pure states. If I understand correctly, the spectrum of an observable is the collection of eigenvalues formed by the inner product of states and hence equal to...

Hi so to those of you who don't know the problem here is a video that explains it very well. - I have an idea on how to measure it, can someone please tell me if, and why it is incorrect. Thank you! Okay so we will have a timer, and a lot of mirrors, set up in a circle, a light beam is fired...

nothing more need to be add(smiling face)

Hi everyone, In purpose to estimate the corrosion degredation in pressure vessels it is recommended to measure the pressure vessel thickness using an U.S. device. My question is how to determine the number of test points on the shell/caps surface as a function of the pressure vessel size...

The link is https://www.su.se/english/research/scientists-film-a-quantum-measurement-1.487234 How do they arrive at this distribution over time? It does not appear to be saying that this is the prediction (in it were, then why the "filming"?), and measurement of a single atom's superposition is...

Hi all Is there any way to measure frequency deviation in a recorded frequency modulated time domain data? The little research i have done on net mostly concerns with frequency deviation measurement using spectrum analyzer in real time i.e. data continuously received on spectrum analyzer while...

Susskind explains how if you prepare an electron along any axis n (with an electromagnet) and then measure it along any other axis m, the probability of finding the electron with spin up or spin down is given by the angle between the axis. I have left out the linear algebra, because my question...

To want to know the exact quantity of an object whether it be it's length, width, weight etc... Doesn't an absolute measurement only exist in the math/our human Minds. Then go down to quantum scales and that gets even harder because from what point do we even measure from if there is no exact...

Trying to get my head around some basic points of measure theory So rational numbers are dense in the reals. I.e., if with , then there exists an such that . It follows that there are then infinitely many such. The Lebesgue measure of any single irrational (or rational number) is zero in...

There is something I don't understand called CV Bell state measurement. In these two experiments they get two entangled beams "by overlapping phase-squeezed light with amplitude squeezed light with a phase difference of pi/2 at a 50-50 beamsplitter" See Figure 11...

How is the measurement of which path the particle took done for the double slit experiment? When electrons are being sent through the slit. Or when photons are being sent through the slit. Is it an active process or a passive process? I haven't seen an explanation for this and perhaps this...

Suppose we're in a closed and non-expanding universe. You shine a beam of light in one direction such that it circumnavigates the universe and returns to its starting point from the other side. Now you put a detector at this starting point. Would this be a one way measurement of the speed of...

Fermilab's E989 experiment is conducting the first precision measurement of the anomalous magnetic moment of the muon (muon g-2) since the Brookhaven lab did so fifteen years ago. It is currently collecting Run-3 data for this experiment, and said that it would be releasing preliminary Run-1...

the device that I have is the same as the mirror of this truck.

Question --- So I've done a calculation which seems to suggest if I combine the system of a measuring apparatus to say an experimenter who "reacts" to the outcome of the the measurement versus one who does not. Then the change in entropy in both these situations is bounded by: $$ \Delta S_R...

WARNING: Topic is very pedantic. I have used a set of different physics books over the years, and they have all had a focus on the topic of significant figures, error margins and measurement. I have never quite understood these concepts fully and the relationships between them. One aspect I...

Consider the problem in the attached image. The difference between A and B is 0.0020(20). How does one use the least squares method, particularly in matrix form, to find the best value of the masses of A and B respectively, as well as the Q-value? Aren't more measurements needed for the masses...

https://en.wikipedia.org/wiki/CPT_symmetry says "CPT theorem says that CPT symmetry holds for all physical phenomena" - e.g. we could imagine decomposition of given phenomena into Feynman diagrams and apply CPT symmetry to all of them. However, for some o processes such reversibility seems...

Hi Pf I am looking at the figure in wiki about quantum teleportation. https://en.wikipedia.org/wiki/File:Quantum_teleportation_diagram.PNG A wants to send a qubit to B . She receives another qubit from a spdc. so she has to make a Bell measurement on them. Has these qbits to be close in space...

Hello there, I am having trouble with part b. of this problem. I've solved part a. by calculating the commutator of the two observables and found it to be non-zero, which should mean that ##\hat B## and ##\hat C## do not have common eigenvectors. Although calculating the eigenvectors for each...

how do we know that measuring effect the result . how can we know weather quant would behave differentially if we wouldn't measure it . and if we do know the difference between quant that had been measured for example one quant can interference with it self if it haven't been measured in some...

It is supposed to find it with the uncertainty propagation, so i tried by it. $$\delta _{n} = \delta_{\theta}\frac{dn}{d\theta}=\frac{\delta _{\theta}\pi sec(\theta )^{2}}{180} = sec(59,3)^2*\pi*1.2/180$$ $$n = 1.68 \pm 0.08$$ But this uncertainty is quite low, so i am trying to understand if i...

Maybe I've got this wrong, because from what I've been able to glean, how a particle measurement affects another particle which can be on the other side of the Universe in principle is agreed to be 'spooky' and it seems that everyone is happy to simply say, yes this is very mysterious and...

I would much appreciate it if someone can help me find a source discussing this topic. I tried a search on the Internet with several alternative ways to express the question, but nothing worked. I have in mind a particular example, but I do not know if it is applicable to this question as a...

Summary:: How to solve this? See attached. This is from Griffiths 3rd edition quantum mechanics textbook, problem 2.7: This is the solution for an infinite square well. I am to find the probability of obtaining E1 where En = n^2pi^2hbar^2/2ma^2. E1 = hbar^2pi^2/2ma^2 When finding the...

A bit of physics history in this article. How Michelson (yes, that Michelson) measured the first stellar diameter (ok, except for the sun) at the Mt. Wilson Observatory. https://www.mtwilson.edu/wp-content/uploads/2019/12/50971-MtWilson-proof.pdf

Consider two entangled spin half particles given by the generic form of Bell Equation in Z-axis: ##\psi = (a\uparrow \uparrow + b\downarrow \downarrow)## where ##a^2+b^2=1## In a (2D) planer rotated (by an angle ##\theta##) direction the new equation can be given by: ##|\psi \rangle =...