Measurement Definition and 1000 Threads

We know that if, for example, two particles are entangled in a state like: |Ψ>=a |0>|0> + b |1>|1>, then measuring an observable on only one of the particles it makes the interference dissapear. But isn't it impossible to measure both particles simultaneously in order to maintain the...

Astronomy Help! :( I'm sure that compared to all the other problems posted here, this Astronomy problem is incredibly easy, but I'm TERRIBLE at sciences and mathematics and really need some help. The problem is: "Although the distance to the Sun is obviously much larger than the distance...

If i already know the wave function then measure an observable what is the new wave function? Is it just the eigenfunction of the observable corresponding to the measured value? And does it stay in this state until something interacts with it?

In regards to data analysis, what would it mean if you measured some quantity, say the speed of light for example, and you measured an average value that was 110% of the true value. If your uncertainty in measurement is LESS than 10%, does that mean that something is wrong with your data or...

I know this is a hotly debated subject here, but what is the general scientific consensus (or most popular definiton) on what constitutes a measurement? Secondly, are there theories where the measurement problem becomes an illusion because of anthropomorphic bias? (To put in a crude...

Do you get electromagnetic standing waves? If so, do the electric and magnetic fields not cancel each other because of their opposite direction in the standing wave? Can such a thing be measured?

How would one measure the position of a quantum mechanical particle? For example, suppose I am aware that an electron lies in a 1-D box of length L. And maybe I wish to know the position of the particle in that box to a certain level of accuracy. I'm satisfied with knowing the position...

Like all beginners to QM I'm really confused about the measurement operation. I understand that measurement is simply a dot product with an "operator" and the result is one of the operator's eigenvalues. Now my question is what exactly is an operator? If someone could explain what physical...

I just had a question about quantum mechanics that has been muddied somewhat by pop culture's understanding of the quantum world. My question is this: Would it be correct to say that the reason that there is inherent uncertainty in measuring the quantum world is because of the methods of...

Did any scientist do experiment to prove that current measurement changed the past with time stamps on both current and past events? I mean with clear time stamps showing the the past event happened earlier(as proof from a strick time stamp), and it must not be possible to happen if the...

i tried to explain for some one how we can solve the measurement problem and i went like this imagine your self in a room and in this room you don't have any sense so you can't see hear touch smell or even taste but you have a prob attached to your brain but if you don't do the measure you...

Let's say I have made a measurement of some sort of a quantum system. That is, I have some macro/classical devices whose states have numbers associated with them, and their resulting states depend (in some way) on a quantum system. So I arrange the lab-plus-quantum system as desired and note...

What do you think these Weak Measurement, Quantum Uncollapse Tests. Re-write QM?? http://www.scienceagogo.com/news/20080706233709data_trunc_sys.shtml http://www.sciencedaily.com/releases/2008/08/080806140128.htm Are they going to re-write the quantum mechanics?

Hi all, I am trying to measure the piezoelectricity of a polymer film using a picoammeter. Right now I am trying to figure out the best way to make the connection to the film without sputtering electrodes onto it. I figure copper adhesive tape or silver paste might be the best way to go but...

Hi everyone, I've recently been bugged by a question I can't seem to find a reasonable answer to. It's about an apparent contradiction between how the wave equation is supposed to evolve in time according to the schrodinger equation and the measurement formalism in QM. Suppose I have any...

Hi all: I'm working in a air pollutant level sensing system, to measure the common air pollutants and their level. I begun with this some months ago (In fact I've taken the others work's in my hands), and used electrochemical gas sensors for low ppm sensing (Up to 50ppm) and with 0.1ppm...

Homework Statement Two scales on a voltmeter measure voltages up to 20.0 and 30.0V, respectively. The resistance connected in series with the galvanometer is 1680 ohms for the 20.0V scale and 2930 ohms for the 30.0V scale. Determine the coil resistance and the full-scale current of the...

Homework Statement Would 85 uV (Micro) be 8.5 x 10^-5 V ? And would 600ps be 6x 10^-10 S ? Ehhh I haven't slept in weeks, I just can't focus. Homework Statement Homework Equations The Attempt at a Solution I used the fact that 1u = 1x 10 ^-6 and then I used 1V/1000000uV x (85 uV) and for...

Hi Guys I am new engineering and would appreciate any advice or ideas on this project. I need to measure the height above sea level of a small vehicle that I am building.. My first idea was GPS, but the vehicle is going travel under a thick steel structure, so it will not work. I thought...

It seems to me a typical gasoline car has wastes about 95% of the gasoline energy before any rotating energy gets to the wheels. Here's my reasoning. I once measured my cars efficiency (an old Renault 5). I drove 100 km/h (28m/s) on a flat and level freeway, with no wind, and set the gears...

How do (PWR) nuclear plants determine how much fuel is left? Do they measure it? I heard they calculate it, but i was wondering if any measurement is done? Thanks.

I need some advice on how to write uncertainities on different measurements. I need this urgently. Thanks:cool:

Mathematically, I understand the following eigen equation: A|a> = a |a>, where A is an operator, |a> is the eigenstate, and a is the eigenvalue. In terms of mathematics, it is nothing more than a linear transformation. However, physically, what does the equation mean? Is it equivalent to the...

For my undergraduate project, I have been tasked to measure group delay of dielectric mirrors. I have found only papers that point mainly to use a Michelson interferometer using white light interferometry. I have googled and found how to construct a standard Michelson interferometer. However I...

Give a measurement result by the correction and uncertainty in the calibration of the thermometer indicator! With reference thermometer are measured 135.14 ° C, with another thermometer which was calibrated with reference we got the following values: 140.15 ° C 140.14 ° C 140.13 ° C 140.12 ° C...

I would like to know, does anyone know of specific examples of quantum measurement of energy? The reason I am asking is that anything that is observed is ultimately in a position space as opposed to momentum space (for example, it might be specific position of the errow of a measurement device)...

Hi guys, I am currently undergoing some measurement with TCS230 light to frequency converter, its actually a cmos color sensor, so the measurement result was made in period measurement. For white the output was not almost the same, but actually according to bitmap resolution, the R,G,B value...

Hi, I'm doing an experiment that gathers one data point approximately each second. I have plotted all the datapoints on a graph. The graph has many tops and bottoms. Now due to the fact that there are so many data points and that I can visualle tell that there are several overal trends: one...

What is a smallest system which can be considered a 'measurement device' in terms of CI. How many atoms does it consist of?

Everyone, I am a Mechanical Engineer working on a design modification (or existing product recommendation) for an Idaho National Laboratory project. What follows is the situation description. At the end is the question. You can skip down to the bottom of the post (which details the...

Homework Statement What is the PHYSICS metric unit for the measurement of: a. velocity b. mass c. kinetic energy d. height e. mass f. acceleration of gravity g. potential energy? What is a source that converts a great deal of nuclear energy into energy you use..{ besides...

This problem seems straightforward and easy enough, but I still want to check my answers. Suppose the pressure of the bulb (light bulb I'm guessing used in experiment) is 20 psi (absolute) at 20C. What would you predict the pressure to be at 0C? What would you predict would be at 100C? I...

Homework Statement If the slope of your gradient turns out to be 4.041 s^2.m^-1 then what value would you obtain for g? State your answer in m.s^2 and to 3 significant figures. Homework Equations T^2 = (4 pi^2 e1 / g) - (4 pi^2 e0 / g) This is the one I'm supposed to use. Other ones...

How do we measure the young's modulus of powders (particle size D50 is around 50 microns)? Quasi static methods like compression , tensile etc are not recommended for powders like materials. WHat modifications do we need if one wants to use compression method ?

Hi, my group and I are doing an experiment on forces experienced on a baseball. Our setup involves the baseball attached to a motor, which is coupled to a cantilever beam (1/2 inch thick, 7 inch long aluminum rod). The beam has a strain gauge attached to it and we are recording data with...

Hello folks, Does anyone know any formula about g-force measurement when launching into orbit? For example, 1 G at ground, 3-5 G during launching, 0 G at orbit. Thanks, Tim

Hello, another graduate school advising situation. Well, like everyone else (almost), i am interested in possibility of TOK and the like; however, since I am more of a humian empiricist I typically become bitterly skeptical of String-theory and Branes and such. Since in my opinion those...

Anyone can give me the example (device)of measurement of fluid flow??

I read two articles recently and I am wondering if I have the correct interpretation of them. They deal with joint weak measurement and Hardy's paradox. Is the result of the "Direct observation of Hardy's paradox by joint weak measurement with an entangled photon pair" paper indicating...

Homework Statement If x = (7.2\pm0.6) m, determine the value of ln x with its associated uncertainty. (Ans is 1.97 \pm 0.08) Homework Equations A = k{B^m}{\rm{ }} \Rightarrow {\rm{ }}\frac{{\Delta A}}{A} = m\frac{{\Delta B}}{B} (perhaps?) The Attempt at a Solution i tried to...

First of all I wanted that I am not a physicist. I have an introductory knowledge gained from college, tv, news, magazines etc. So that's why came here with this question. I thought maybe you could help me with. So the question is simple. As technology has advanced we are able to measure...

What is the most accurate way of measuring the amount of calories a person has burned in a certain time period?

Suppose we prepare a system in some properly normalized superposition of the spherical harmonics: A|11> + B|10> + C|1-1>. One of the fundamental results of quantum mechanics is that, if we measure L_z, we will collapse the state of the system onto an eigenstate of the eigenvalue we measure. My...

I want to measure level of water at two positions in tank. How to measure it? |-----|_> here & | ----|_ >here |____| Fig. Tank when water level reach to certain levels(1,2) o/p voltage should be generated. I hav to connect it to 24 V DC PLC i/p. I need simple and easy solution. PLZ help me.

Just thought I would get a couple of opinions from you guys on something I find truly amazing. In Brian Greene's Fabric of the Cosmos he explains how the delayed quantum measurement experiment works. A single photon has already passed through a beam splitter and made the 'choice' of whether...

hello. I am working to understand and design a UV sanitization device. What is a good resource to learn about irradiance and its relation to distance from a surface. Secondly, in real life, how is irradiance measured? Given a surface area, I would need to specify bulbs of certain...

What is meant by a "partial measurement" or "partial measurement in the Bell basis?" More specifically, I'm trying to read the Wikipedia article on quantum teleportation, but I don't know what is meant when they say Alice performs a partial measurement on her qubits.

Homework Statement Knowing the given equations, k is equal to a measurement where J(t) implies some local coupling between the observer and observed system. If a field is considered to collapse J(t), how would the two manifest into a single expression. Homework Equations...

Say we have an electron in a position eigenstate \delta(P-x) at point P at time t_0 . We also have a detector at another point Q. At t_0 , the probability of the detector registering the electron is zero. After a certain time T , the time evolution of the wave function generates a...

If the current, voltage and power are measured at the terminals of a device containing only resistance and inductive reactance, how many values of R and X can be determined from just 1 A.C. measurement? (P.S. This is not homework but an elec engineer who has been stumped)