Measurement Definition and 1000 Threads

what is the difference between observation and measurement in reference to quantum mechanics?

A mercury thermometer with only the 0 degree Celsius and 100 degree Celsius markings on it was given to a student, and the student was asked to use it to estimate the temperature of a block of ice cream. I'm not sure, because the scale stops at 0 and mostly likely the temperature of ice...

I understand that an object can exist in many possible locations, and that when you're not looking, it is a wave. It's only when you look that it manifests itself into a particle. But Is that also dependent on the measurement of sound? Does an object materialize when you hear it, or feel a force...

I have laser drilled hole thin ceramic specimens and I am required to measure the diameter of the holes. Suggest me some methods.

For a pin photodiode, risetime=bandwidth/0.35 i get ~3ns for s5973 will it be affecting the measurement of 10ns laser pulse? How can i reduce the rise time?

In communicating with an astronaut on the moon, 3.8x10^8 m from earth, what is the minimum time delay in getting a response to a question? The answer in the book is given as 2.5 seconds.Have they simply used; ( (3.8x10^8) / c ) x 2

Transfer function of flow measurement system HELP! 1. I have attached the question, which is to derive the transfer function of a volumetric flow measurement system... 2. I know of the following relevant equations: F = Ma = MD^2.x Flow f = area x velocity and f through a...

Hi all I have assigned a task to measure distance at two points separated 200 mm apart on a cylinder having diameter about 300 mm dia. The distance from point and measuring point will be 150 mm and that of for second point will be 150.05mm.I have an idea of using two lasers mounted 200 mm...

How can velocity be measured in quantum mechanics since one can not measeure position without disturbing the particle?

Not sure if anyone will be able to answer these questions but it would be good if someone would give it a shot. A friend recently explained the measurement problem to me and i thought of a few questions which he was not able to answer. A) Do animals count as observers, and can they cause...

Just trying to follow Giancarlo Ghirardi reasoning in his book about differentiating between pure and mixture esembles. Is it possible to perform a measurement on an observable that, if it were in a superposition, a certain value would return?

Question - Regarding a cnc cmm controller, What is tunneling? How is this measured? What impact does the cmm structure have on this characteristic?

I am trying to design a system to measure the distance between two RF transceivers with as small of a resolution as possible. Time-of-flight measurement is nice and easy to do, but it has a poor resolution with low frequency timers. I am thinking of using a low-cost mcu that will probably have a...

Hello Everyone, Here is my situation: I am using a laser to take distance (height) measurements on a variety of surface types (e.g. mirror, machined surface, plastic, etc.) and I would like to quantify the repeatability of the laser measurements on each surface type. Please note that I care...

Hallo alle users, as the title indicates, I have a question about measurement of thin film thickness by means of spectral reflectance. Given, the to be measured thin film has thickness less than 600 nm, but the measuring light has only wavelengh larger than 600 nm. Does it mean, that the...

I came up with something to think about while freezing in my room... How can one measure the temperature in a room withought traditional termometer. Alternative formulation of the question - is it posible to construct a termometer that would measure such temperatures as are measured in a...

This is not a question about relativity per se, but relates to it sufficiently I hope. Standard values for many scientific constants are defined, and ideally in the most universal way possible. For example, the standard length unit, a meter, is defined with respect to the distance light travels...

Hello all, In the following article I found through google, they explain how spin is measured: http://news.softpedia.com/news/Why-Is-Quantum-Mechanics-So-Weird-40009.shtml I understand how the Stern-Gerlach experiment works, but the article doesn't go into much detail about the next...

Why is the modern value of Hubble's constant so different from today's measured value? At first I thought it was because the Hubble constant is related to density via: ρ_c = 3H^2/(8*π*G) but in the past 2011 - 1921 = 90 years, I don't think the density could have changed that much since...

This is a question that's been in the back of my mind since I first learned quantum mechanics. There seems to me to be some tension between the postulates of unitary evolution and state reduction upon measurement: basically, any quantum system ought to evolve unitarily; so in principle, every...

I am building an iPhone app where the iPhone is just going to sit on my desk measuring the distance to Earth's core. I will build a calibration function into my app to reduce the variation in the estimate. How, then, should I go about calibrating it?

Hi there, Ok, so if you know the interactions, etc., you can calculate from time0 the probabilities for certain results at say time8. But say, however, we perform a measurement before time8. Will the original predictions for time8 still hold if a measurement is performed prior to that...

"Measurement disturbs the system." Okay so I explained the uncertainty principle to my non-scientist friend, and he came up with a basic thought experiment. I know there is something wrong with it, so I read paragraph 8 from here: http://www.oberlin.edu/physics/dstyer/TeachQM/misconnzz.pdf...

Flow rate measurement: Venturi vs Sharp edged circular orifice. Help! :) Homework Statement Hello guys, I am having trouble answering these questions. I know the the discharge coefficient for a venturi is always higher than that of the sharp edge orifice. Can you guys help me out with the...

I went to see an orthopedic specialist this year, when I was 15 years and 5 months old. I am 5 ft, 11 1/4 in. The specialist looked at my then-recent X-rays and I was not even halfway done growing. (I'm pretty sure I scored a 2 out of 5.) I am due for another X-ray sometime next year, at...

Hi everyone, I was thinking about what it means to talk about the "momentum of a particle" and I tried to come up with a little scheme to help me, but as of now it has only made more confusion... This is how my thoughts went. I know from quantum mechanics can one can relate classical...

Edit: Before posting in this thread, we'd like to ask readers to read three things: The https://www.physicsforums.com/showthread.php?t=414380". Don't forget the section on overly speculative posts. The paper http://arxiv.org/abs/1109.4897" The previous posts in this thread And...

Any examples of real-time energy measurement in homes? Hi :-) My professor told me that he thinks that if people are made more aware of the energy they consume in each action they perform (e.g the amt of electrical energy consumed by heating the stove for 15 mins..and such day to day...

Hams and Raedt gave a quantum computational algorithm to calculate the density of states of a spin system. Starting with an initial random state, they obtain the time evolution of the state. Later they take the inner product of the evolved state with the initial state. How does the inner...

Hi all, In our assignment, we were given this question: [PLAIN]http://img685.imageshack.us/img685/4854/prob213.png I know that for (a), the answer is the first energy eigenstate since the measured energy corresponds to it. I'm not sure about the situation in (b), though. Does...

Hi, In QM, when we make a measurement, our wavefunction collapses into one of the eigenstates of the operator. This process is supposed to be random for any single measurement but obeys some statistics if we make a large number of measurements. Could someone explain how we know that it is...

Hi, I think that this is (should be) a straight forward question: when conducting the double slit experiment, is there a relationship between the brightness / measure of the light source and the sum of the "peaks" from the interference pattern? (I have done a number of searches but can't find...

Does anyone know of a good textbook that would go in depth on current mirror circuits? What about methods and information on measuring low currents? My sedra and smith book does not talk anything about these subjects in detail.

How are ultra cold temperatures measured? For example, sometimes I see things measured in nanoKelvins. I'm thinking there has to be direct contact since the vacuum is already hotter than this, but how is it actually done?

Hi, I have deposited a film of dielectric on SiO2 substrate. Then, deposited metal dots on the top of dielectric film to measure electrical properties. I want to measure capacitance using metal dots on the top of dielectric. Since I have SiO2 as a substrate, I can not make a parallel plate...

Is it possible, practically or theoretically to measure the momentum of a quantum particle without altering the momentum? (the only real world tests I have read about involve collisions with other particles) If so, what would be result of a measurement of momentum have if interjected between...

Is conservation of energy, momentum, and other physical properties absolutely true in quantum mechanics, or only on average? As an example, think of a single particle in free space. Measure its energy, and write down the result. Then look at where it is, and measure the energy again. You'll...

I wondered how you can measure (static) pressure, with an as high as possible accuracy. Could you share your experience about which sensor and setup you allready used? I would like to measure the static pressure before and after a fan with an accuracy of 10[Pa]. Do you think this is possible?

What is the best way to hold it against multimeter sharp probes? The component is quite small and i want to avoid inaccurate result due to my hands holding it / placing it on the bench top

Hello, I wasn't sure exactly where to put this thread. Figured this was the most relevant section. Anyway, I wanted to know what exactly do meteorologists mean when they say that a region will receive 5mm or 10mm of rain during the evening. I read this wiki page...

This is actually a GRE problem, I'm just trying to go through and understand them all for studying purposes, but I don't understand how to do this one at all. Homework Statement A student makes 10 one-second measurements of the disintegration of a sample of long-lived radioactive isotope and...

I have two current signals from a two color Si-photodiode/PbS-photodetector. I want to measure the signal with the Stanford Research Lock-In Amplifier 830. I read in the manual that I can measure currents with the SR830. Does anyone have experience with this? Do I get better signals if I...

Hello In an electron diffraction experiment usually the diffraction rings are blurred. My question. If measuring the diameter, should I measure to the inside of the ring, the outside, or take a guess where the middle of the ring is and measure to there? Thanks

hey, could someone tell me if it is possible to measure the angle of twist of a rigid shaft subjected to a torsional moment at one end by using eddy current testing?

To calculate the height of a crane which is on top of a building, dennis measures the angle of elevation to the bottom and the top of the crane. these were 62 degrees and 68 degrees respectively. if the building is 42 metres high find the height of the crane. I'm asking for a friend, excuse the...

Weak measurement show that you can get "partial/probabilistic" which-way info and get a "partial" interference pattern. Deduction 1: Does this mean that weak measurements prove that we can control the degree of randomness? (either of individual photons or average of a thousands of photons)...

Does it explain what occur during strong measurement or "approximately" solve the measurement problem? I'm asking because below it is mentioned that "it is this uncertainty that creates the uncontrollable, irreversible disturbance associated with measurement". Does it mean that measurement...

Hello Rockwell B or Rockwell E - which one is better to measure the hardness of aluminum alloys? Thank you!

I'm working on a high power multi-phase DC/DC converter where the load current has some fast transients. We can easily measure the output voltage in the time domain, and also measure the power distribution network impedance in the frequency domain. So, I think I would try converting the...

I pasted a paragraph from http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-845-quantum-complexity-theory-fall-2010/lecture-notes/MIT6_845F10_lec02.pdf" below. ------------------------------ Consider the following matrix which represents a 45◦ counter clock wise...