What is Measurement: Definition and 1000 Discussions

Measurement is the quantification of attributes of an object or event, which can be used to compare with other objects or events. The scope and application of measurement are dependent on the context and discipline. In natural sciences and engineering, measurements do not apply to nominal properties of objects or events, which is consistent with the guidelines of the International vocabulary of metrology published by the International Bureau of Weights and Measures. However, in other fields such as statistics as well as the social and behavioural sciences, measurements can have multiple levels, which would include nominal, ordinal, interval and ratio scales.Measurement is a cornerstone of trade, science, technology and quantitative research in many disciplines. Historically, many measurement systems existed for the varied fields of human existence to facilitate comparisons in these fields. Often these were achieved by local agreements between trading partners or collaborators. Since the 18th century, developments progressed towards unifying, widely accepted standards that resulted in the modern International System of Units (SI). This system reduces all physical measurements to a mathematical combination of seven base units. The science of measurement is pursued in the field of metrology.

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  1. G

    Why is impossible measurement of the magnitudes when his val

    Why is impossible measurement of the magnitudes when his values are smaller than Planck units??
  2. A

    Uniformity of thermal vibrations

    Hello, I have a question on the nature of vibrations due to thermal energy. Earlier today I read this article which talked about cooling a glass string to near absolute zero using feedback from a high precision sensor. http://phys.org/news/2015-08-smallest-vibration.html what I understood from...
  3. Tomvader1988

    Does time dilation affect only the measurement of time?

    As I understand, 'Einstein's mirrored light clock' shows us that a vessel (containing said clock) traveling at any speed greater than that of a duplicate, at rest will observe a slower passage of time. I understand that this is because of simple Newtonian physics that shows us that in the case...
  4. ezfzx

    Archived Should Labs be Written in Pen?

    A student asked if the labs need to be written in pen. Apparently, the lab instructions say to do so. Actually, I forgot that was in there. It’s kind of a hand-me-down set of instructions from ancient times (a few years ago). I should probably take it out, but it's worth a short discussion. The...
  5. S

    MHB Black Plastic Lid - Measurement Ratio

    Object: Black Plastic Lid $C$ = Circumference (cm) $D$ = Diameter (cm) Ratio $= \frac{C}{D}$ Ratio $= \frac{30.75}{9.46} = 3.25$
  6. jk22

    Measurement problem and computer-like functions

    Suppose we define the measurement of an observable A by v(A) v being an 'algorithm giving out one of the eigenvalues each time it is called' (we accept the axiom of choice) In this context we have in particular v(A)≠v(A) since when we call the left hand side and then the right handside the...
  7. R

    Is Decoherence essentially a measurement? Then what?

    2 basic questions from a non-physicist (sigh!). Is decoherence essentially a measurement? And if so is the system of quantum particles set into the classical world forever? Or is there a mechanism by which it will evolve again into a superimposed state? Secondly, if the particle (as in the 2...
  8. quantumfunction

    I Entanglement Swapping and measurement vs. observation

    I think entanglement swapping shows the difference between measurement and observation. A measurement isn't as important as observation at least to subatomic particles. Here's some key points...
  9. C

    Future time measurement units for a tidal locked exoplanet

    Lets assume that a human colony wants to reform time measurement units for more practical. Reasoning: -circadian rhythm a bit exceeds 24h, so perfect day would be around 24h and 10 minutes ( http://www.circadiansleepdisorders.org/info/cycle_length.php ) -readjusting year zero, somewhere...
  10. Cobalt101

    Delayed choice measurement subsequent analysis

    This is a variant associated with the Scully and Druhl signal-idler photon delayed choice experiment, as described and discussed in Brian Greene's Fabric of the Cosmos. The commentary notes the "delay" may be configured to happen a very (years) long time after the photons pass the two...
  11. jk22

    Measurement operator for Chsh experiment

    The experiment is described at p26 of http://arxiv.org/abs/quant-ph/0402001 In this experiment we see that we sum measurement results and not measure the sum. Is then the quantum measurement operator not : $$S=A\otimes B\otimes\mathbb{1_{64}}-\mathbb{1_{4}}\otimes A\otimes...
  12. Jimster41

    Relationship between measurement and temperature

    A system at absolute zero (ground state) can't be be divided into observer and observed, can it? I'm struggling with the relationship between superposition, decoherence and temperature. Decoherence requires information. Information requires energy. Though multiple basis of "information" can...
  13. Hanyuri

    Questions on Rs measurement by four point probe device

    Hi all, I am working on electronics material (using metal oxide as an active layer in TFTs). Currently, I'm trying to measure the sheet resistance (Rs) of CuO thin film (~100nm in thickness). My lab uses Agilent B1500 device for measuring the Rs. I met some problems when carrying out the...
  14. C

    Index of Refraction Measurement Uncertainty

    Hello All, I am having some issues with calculating the measurement uncertainty when there is a mismatch in the index of refraction between a fluid and an interface. If am using an unobtrusive measurement technique such as Laser Doppler Velocimetry, how would I be able to quantify the...
  15. Jesayntly

    Copenhagen - What qualifies as "measurement" and "observer"?

    Hey guys and gals, clearly I'm new here, not only new here but new to QM (relatively speaking). I've read a few threads here pertaining to a thought I've been pondering on but the answer doesn't seem clear. In the Copenhagen interpretation, what qualifies as a "measurement", and/or what...
  16. Anind

    Measurement of unknown resistance using potentiometer

    [Mentor's Note: Thread moved to homework forums from another forum] Figure shows a potentiometer circuit for comparison of two resistances. The balance point with a standard resistor R = 10.0 Ω is found to be 58.3 cm, while that with the unknown resistance X is 68.5 cm. Determine the value of...
  17. Enoy

    A New MINOS measurement of neutrinos speed through earth

    Most presice measurement to date done by MINOS of neutrino time of flight through Earth published two days ago, once again found neutrinos slightly faster than light speed within statistical errors. Only when they extend the band with systematic errors doesn't neutrinos surpass light speed...
  18. ChrisVer

    Inclusive/Exclusive measurement of B-mesons

    What is the differences between inclusive and exclusive B-meson measurements? I think the inclusive is that in the case eg of a B\bar{B} mesons creation, we use the one ##B## meson as a tag (and measure all its products) while we don't measure the mesonic decay of the other ##B## but only the...
  19. VALENCIANA

    Collapse with and without measurement

    I read yesterday about a double-slit experiment in which the researchers set up the device ready to make the measurement, but didn´t make the measurement and the wave function collapsed. Then they did it by taking the measurement and it also collapsed. What does it mean that just by setting up...
  20. person_random_normal

    Current Density: Definition & Measurement

    What is current density
  21. can12345

    Effect of Air Bubble on Differential Pressure Measurement

    What is the effect of air bubble in transmission line when measuring differential pressure by the using an electronic transducer? Purging is a must before measurement, however if we still have some bubble inside the transmission line or in front of transducer diaphragm, how it may effect to my...
  22. brainpushups

    Primary Sources for Measurement of g

    I have read, and seen it claimed in another old thread, that Galileo was the first to measure the free fall acceleration near Earth's surface. I have not found any source that explains how he did so or what his result was. I've skimmed through most of his Discorsi and have not seen it there...
  23. T

    Quantum Quantum decoherence and measurement

    I keep hearing about things like "quantum decoherence" and the notion that measurement doesn't need a conscious observer. However, I haven't really seen these topics discussed in any of the textbooks I've used (mostly on the level of Griffiths and higher). I haven't even seen a reference to...
  24. ChrisVer

    Averaging measurement with stat +sys errors

    Homework Statement You make a measurement of two variables with 100% correlated systematic uncertainty: x_1 \pm \Delta x_1^{stat} \pm \Delta x_1^{sys} = 1.0 \pm 0.1 \pm 0.1 x_2 \pm \Delta x_2^{stat} \pm \Delta x_2^{sys} = 1.2 \pm 0.1 \pm 0.2 The average is taken by: \bar{x} =...
  25. can12345

    Pressure Measurement: Big vs Small Diameters

    What is the effect of transmission line while measuring pressure value? I want to learn difference between big and small diameter of measurement line (transmission line).
  26. jk1956

    Stellar aberration measurement

    Hi everyone, I am interested in measuring stellar aberration as a challenge to myself; I am more of a physicist than an astronomer. I have a fair knowledge of telescopes and imaging. I would appreciate if somebody can give me instructions or point to some references on: which star to select...
  27. F

    The relation between classical from quantum vs measurement perspective

    What is the relation between classical from quantum vs measurement problem. On one hand they seem to be related on the other they seem to be of different nature. We always see our screens on front of us and not 100 meters away, that we say is classical object although the screen is a quantum...
  28. Runei

    Measurement, Quantum Wierdness and Single-Effect Events

    Hello, I was reading an article the other day regarding measurement and 'Quantum Wierdness' and it made me think about this whole deal with measuring stuff in QM. [EDIT: Article: http://www.anu.edu.au/news/all-news/experiment-confirms-quantum-theory-weirdness ] The thing is I regularly work...
  29. A

    Position measurement in Non-Relativistic QM

    I've read several times in textbooks that in NR-QM you can measure with exact precision the position of a particle if you don't care at all for the momentum (because the uncertainty of the momentum will be infinite), it always seemed reasonable enough for me but now that I think about it, it...
  30. G

    What's the difference between fine and coarse measurement?

    Would anybody pleas tell me what's the difference between fine and coarse measurement? I am reading a paper named "Electronic distance measurement-An introduction" in which fine measurement and coarse measurement is mentioned. here is the exact paragraph: "The transmitter includes a master...
  31. ChrisVer

    Measuring Higgs Spin: A Guide to Detecting Symmetry in Decay Products

    How would someone measure the Higgs spin? I have a feeling that the spin would somehow affect the symmetry of the decays...? A spin zero would have to show a spherically symmetric distribution of decay products (independent on ##\theta##, maybe a little dependent on ##\eta## due to the...
  32. P

    Air flow measurement with multiple fans

    Hi, My company builds machinery with multi-zone hot air dryers. Each dryer has 2-3 supply blowers that push air through an electric heater and then through a duct into a plenum (one plenum for each dryer zone) at the top of the dryer. Each plenum is fitted with multiple air nozzles that...
  33. atyy

    Measurement problem in classical probability

    This question is inspired by ephen wilb's https://www.physicsforums.com/threads/quantum-theory-of-others.816818/#post-5130620. In Bohmian Mechanics, everything is exactly as in classical probability theory. How, from the point of view of BM, does the measurement problem arise? Since the...
  34. can12345

    Effect of bubble on pressure measurement

    Homework Statement During measurement of flowrate inside a closed circle pipe system, we can have some bubble which can be sticking on orifice plate, or pressure tap, or transmission line. What is the effect of bubbles in these systems? Homework EquationsThe Attempt at a Solution
  35. L

    How to represent hidden measurement by mixture of unitaries

    Dear all, I have struggle for the problem for 2 days... And searched a lot materials on web but still can't solve for it. Question, A hidden measurement with n distinct outcomes is the average 2^(n-1) unitary maps. If it's too elusive, how about the case when n=2.
  36. Rajkovic

    Measurement Rules Quantum Universe

    Is a new article, btw June 2, 2015 Experiment Provides Further Evidence That Reality Doesn't Exist Until We Measure It http://www.iflscience.com/physics/measurement-rules-quantum-universe http://www.sciencealert.com/reality-doesn-t-exist-until-we-measure-it-quantum-experiment-confirms any...
  37. can12345

    First and second order terms in pressure measurement

    Hello everyone, What does it means first and second order of pressure measurement value? Whats the main difference?
  38. Julian Blair

    Measurement of a Hydrogen qubit?

    Given a 2 state hydrogen atom in a superimposed state, how does one measure it for either of its two states?
  39. can12345

    Optimizing Averaging Algorithms for Reliable Pressure Measurements

    < Mentor Note -- thread moved to HH from the technical engineering forums, so no HH Template is shown > Hello everyone. I have such a task to fullfill. I am using dsa3307 Differential pressure scanner. Can someone give me an idea? How to achieve a result for this topic.."Implementation and...
  40. H

    Measurement of viscosity of polymer

    Homework Statement if we have only a measuring cylinder (500mm high and 50mm diameter), a stop-watch, a ruler and a 100μL syringe. We assume that the density of the suspension is 1g/cm3, and that the polymers are spherical How can we determine the viscosity and the volume fraction of the...
  41. C

    Speed limitations of pot & arduino for angle measurement?

    If I am using a continuous rotation potentiometer on a pulley, and I want to use an Arduino to convert this reading into an angle as part of an angle control system, then what are the limitations for how fast the pulley can turn? Specifically, if the pulley is turning at 450RPM, will a...
  42. neilparker62

    Lyman Series Wavelengths - measurement standard?

    Am just wondering what the currently accepted measurement standard is for the Lyman series spectral lines. At NIST I find the following set of measured wavelengths (nano meters): 91.9342 92.0947 92.3148 92.6249 93.0751 93.7814 94.9742 97.2517 102.5728 121.56701 At...
  43. A

    How does measurement time affect laser linewidth measurements?

    I am trying to measure the linewidth of a diode laser using the self-heterodyne technique. The laser specs says that the linewidth is ~100kHz at 1us. I guess I am confused by the "at 1us" and how exactly that translates to measuring the linewidth myself by looking at the beat note on a spectrum...
  44. jdawg

    Simultaneous measurement of the momentum component px

    Homework Statement The uncertainty in the position of an electron along an x axis is given as 38 pm. What is the least uncertainty in any simultaneous measurement of the momentum component px of this electron? Homework Equations Position uncertainty = h/ delta p (delta p is the uncertainty in...
  45. F

    Local measurement of the Vacuum Energy?

    Is it possible to measure the vacuum energy locally? I wonder if it might change with gravity? I'm told that we can measure the vacuum energy globally by measuring the acceleration of the universe's expansion. But can we measure it locally? Or are all local measurements independent of the vacuum...
  46. mishima

    Rough lab measurement of transformer inrush current?

    Hi, Id like to measure inrush current for various salvaged transformers (unknown windings, but probably 120/24) to the nearest 10 mA. I only have a simple DMM and soundcard scope. It seems that a clamp meter has this capability; if a clamp meter is the best approach, can I construct my own...
  47. neilparker62

    Measurement of Hydrogen 1s 4s transition frequency

    Has this been accurately measured yet? Google searches yield results for H 1s-2s and H 1s-3s transitions but not 1s-4s.
  48. Delta2

    Humidity definitions and measurement devices

    I know there are three definitions of humidity. Absolute , relative and specific. Can you tell me if on a typical commercial device (such as the one i have in a clock i have) that measures humidity as percentage is it the relative humidity that it measures? Can the percentage become greater...
  49. fowl_bob

    I want to teach "measurement" to grade schoolers

    I have a family member in a private grade school and I am organizing a teaching plan for those grades. I was struck by how measurements are integral to the learning and understanding of so many facets of physical science and math. I got good feedback from an initial try by teaching distance...
  50. V

    Total radiant flux measurement of an LED with an optometer

    Measuring the total radiant flux with an optometer of SFH 4550 LED from osram I'm getting ~70mW, If I place 5mm long rubber hose around the led (top 2,5mm of the led is free), the power is reduced to 50-40mW. This does not make sens to me, the led has a half angle of ±3° and emits nothing to...
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