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.

View More On Wikipedia.org
Recent contents Top users
  1. kyphysics

    What is the smallest unit of measurement used that the eye can see?

    There are units of measurement smaller than our eyes can see, but that we use in science. But, what is the smallest one that we can see and work with regularly? I mean...on a traditional ruler, it'd be a millimeter, right? But, we can obviously go smaller - even if a ruler doesn't mark it...
  2. Dangoe

    B No vacuum anywhere vs the measurement of "c"

    Hi to the community! Glad to be able to ask 1-2 questions here so signed up. As an interested layman with some autodidactic efforts, still can’t see how this happened or got to the value: Question: We defined the second and hence the meter by the speed of light in vacuum, but there isn’t...
  3. Astronuc

    History Recent history of measurement of 1 kg and other units

    I didn't remember the Lavoisier died at the guillotine. The world's roundest object helps solve the longest running problem in measurement -- how to define the kilogram. I knew about the Pt the Pt-Ir standard. I didn't realize that the mass of various 'standards' changed in time...
  4. D

    B Is the Heisenberg Uncertainty Principle a result of measurement inadequacies?

    Quantum mechanics is the most successful theory in physics nowadays. The property of non-commuting operators results in a general uncertainty principle of which the Heisenberg Uncertainty Principle is a special case. Non-commuting quantities happily account for things like the two-slits...
  5. M

    I Time of flight measurement uncertainty

    Hello! I am generating electrons from a 3D gaussian source. The electrons all have the same energy, but the direction is isotropic. The electron source is in between 2 plates that act as a capacitor, and one of them acts as a time of flight (tof) detector. I know the voltage on the plates very...
  6. Jamister

    A Measurement of the phase of coherent states

    It is commonly said that the phase of coherent states can't be measured, just the relative phase between two coherent states. A qubit example: define the states $$|\phi\rangle=[|0\rangle+\exp (\mathrm{i} \phi)|1\rangle] / \sqrt{2}$$ and the measurement operators...
  7. M

    I What does it take to solve the measurement problem? (new paper published)

    Yesterday Jonte Hance and Sabine Hossenfelder published this preprint on the arXiv: https://arxiv.org/abs/2206.10445 What does it take to solve the measurement problem?
  8. Bertin

    I Nuclear Physics: Yearly Time Measurement

    Halves-lives and average lifetimes, when studying nuclear decay, are often expressed in years even though years are not standarized, at least in SI (as far as I know). Borrowing the convention from astronomy and astrophysics, I usually take 1 \mathrm{yr} to be equal to 365.25 days of 86400...
  9. J

    I Geiger counters and measurement

    I have the following elementary confusion about how measurement and collapse work in quantum mechanics. Place an unstable particle and a Geiger counter in a sealed box. The particle can be in two states: not decayed (N) or decayed (D). Scale time so that one unit of time after the particle...
  10. A

    Measurement of actual CO2 mass emitted from a diesel engine

    I was wondering if there is a method to measure the actual total mass of carbon dioxide (CO2) emitted from a diesel engine used with a generator for power generation (https://www.cat.com/en_US/products/new/power-systems/electric-power/diesel-generator-sets/1000028914.html). Infrared CO2 sensors...
  11. V

    Significant digits rule when determining radius from diameter

    Probably, to satisfy the significant digits rule for division, we should consider ##r = 5.0 \div 2.0##. But I'm unable to come up with a reason why significant digits rule should not apply to ##r= d \div 2##. Also, if we apply significant digits rule to this calculation then we loose accuracy...
  12. O

    B Parallel light reflection for a one-way speed of light measurement setup

    Hello, Is there a mirror that will reflect light in parallel trajectories ? If yes, is the reflected light in sync, and will all beams hit a flat surface simultaneously ? Thank you
  13. tworitdash

    A Quantum weak measurement parameter estimation vs Classical Estimation

    I am not an expert in quantum theory. I want to carry out some parameter estimation on a set of data I have. I have a model for the data with the parameter(s) of interest as variable(s). The data available is sporadic, meaning non-statistical or techniques involving no prior knowledge on the...
  14. ofirg55

    I Why Can We Use This Mathematical Formula for Mean Value of Measurement?

    Hi, I'm new to the quantum world, and would like to know why mathematically can we say that for mean value of measurment: <T>=<phi|T|phi> ?
  15. M

    Measurement of speed using redshift or blueshift

    The solution on my textbook is 13000m/s toward Earth as the light is blue-shifted I'm able to calculate the magnitude of velocity (13000m/s), but i don't understand why thus is blue-shifted? Since in the lab, the light's wavelength observed is slightly higher than light from Ursa Majoris. So my...
  16. B

    I Question about anapole moment measurement

    Hello! My questions is about this paper, aiming to measure the anapole moment in a molecule. In their derivation, starting from equation (1), they assume that the frequency of the field felt by molecules ##\omega## is much bigger than the energy splitting ##\Delta##. That basically implies that...
  17. janjan

    I Measurement of charge in motion

    In Purcell's E&M Section5.3 "Measurement of charge in motion", he said when a charge is in motion, the force on test charges may not be in the direction of radius vector r. And in next paragraph, he defined Q by averaging over all directions. However, he just measured the radial component of...
  18. M

    A How to simulate an isotope shift measurement

    Hello! My questions are based on this paper talking about King plot non-linearities. Assuming I have 3 isotopes and 2 transitions, I would like to know how well I should measure the transitions (i.e. what uncertainty on the transition value) in order to reach a given sensitivity for the new...
  19. B

    A Question about an equation from anapole measurement paper

    Hello! I have a question about this paper. They claim that the hyperfine and spin-rotational terms can be treated perturbatively (they do perform a full diagonalization, too, but they claim that perturbation theory is good to get an estimate of the effect). I agree with that for most of the...
  20. entropy1

    I Is the moment of the measurement well defined?

    Suppose Alice and Bob do an experiment with an entangled pair of particles, for instance electron spin with SG magnets. Now suppose Alice her SGM is stationary while Bob his SGM is switching fast between parallel to Alice and perpendicular to Alice. So there are two possibilities: correlation...
  21. H

    B Operator as the outcome of a measurement?

    for any set of POVM outcomes it is possible to construct a setup with say one incoming photon and possible outcomes that will click differently. so this is not only mathématics. but what is physically an operator valued measurement?
  22. U

    B Special Relativity and the Measurement Problem of QM

    Given what we know about special relativity and its implication for time and the observer, could this in any way be linked to why the isolated processes of QM are exhibiting everything happening at once and then collapsing to classical physics when bigger objects interact - the measurement...
  23. G

    I Experimental measurement of MTF

    Hi all, I will like to measure the MTF of a lens experimentally. In the set-up, I have my light - target - lens - camera. When my object (target) is at the focus of the lens, I took an image. My question now is, to I move my object across one pixel or few pixels or to move my object across...
  24. akardos

    I Replacing the Measurement standards (SI units)

    What might be better foundational units given the knowledge we now have and disregarding legacy, human-scale units. Perhaps setting some known constants to be the base unit of 1 in that measure. For example, the second, based on the unperturbed ground-state hyperfine transition frequency of the...
  25. J

    Very High Standard Deviation in Excitation Emission Matrix Measurement

    Hi, I obtain really high standard deviations in Excitation-Emission Spectra mainly for the phenolic compounds in olive oil (Em: 290-350nm). Method: I weigh 0.05g of olive oil and dilute it up to 25ml with cyclohexane to remain in the range of linearity for absorbance measurements to correct...
  26. M

    I Measurement problem in simple experiment

    I’m trying to understand the measurement problem using the simplest experiment I can think of--passing a particle P through a 50/50 beam splitter S, sending it down “path A” or “path B” with equal probability. Each path has a detector that can tell us if P was in that path. The detectors...
  27. J

    A Measurement in QFT: Mapping Fields to Theory's Math Formalism

    How do we map experimental measurements of quantum fields, such as those seen in accelerators, to the theory's mathematical formalism? When we see images of particle tracks produced in accelerators such as the LHC, I think it's safe to say a measurement (or series of measurements) has been...
  28. entropy1

    I MWI and interpretation of measurements

    I was wondering, if we have a measurement of, say, spin of an electron, which can yield spin-up and spin-down in the context of MWI, then the electron gets entangled with the measurement device, yielding the wave function ##|Measurement_{spin-up}, Value_{spin-up} \rangle +...
  29. tworitdash

    A Applications of weak measurement of quantum mechanics in other domains

    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...
  30. H

    A What is the achievable accuracy of neutrino speed measurement?

    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...
  31. morrobay

    B One way speed of light in one reference frame measurement

    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...
  32. R

    A Hubble Tension and Cosmic Acceleration: A measurement artifact?

    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...
  33. K

    Possible Results and Probabilities of a Measurement of Operator Q

    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...
  34. P

    I Measurement of a qubit in the computational basis - Phase estimation

    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...
  35. M

    Error calculation in a measurement chain

    [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...
  36. W

    A Measurement from Feynman diagram

    hi, can anyone please give me the list of measurement we can do ON Feynman diagram? Like , branching ratio, cross-section etc
  37. Dario56

    I Du Nouy Method for Measurement of Surface Tension

    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...
  38. f95toli

    Storing device parameter data for a measurement system

    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...
  39. Killtech

    I Weak measurement and the measurement problem

    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...
  40. mncyapntsi

    Uncertainty, volume, and measurement

    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...
  41. Lynch101

    I Rigorous: Where is the Quantum System Prior to Measurement?

    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...
  42. A

    I Problem involving a sequential Stern-Gerlach experiment

    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...
  43. Lynch101

    I Where is the quantum system prior to measurement?

    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...
  44. Sagittarius A-Star

    I Force on Scale in Rocket Scenario: Calculation & Discussion

    [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...
  45. A. Neumaier

    A An interesting paper about measurement and locality in QFT

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

    Is there a common measurement term for joules/volume/°C?

    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...
  47. O

    B Schrödinger's cat measurement

    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...
  48. Dario56

    Understanding the Role of a Voltmeter in Electrode Potential Measurement

    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...
  49. fcici7

    Lost in the Distance: Navigating Measurement

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

    Mirror coating and BSDF measurement costs?

    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...
Back
Top