The result of sampling the property of a system

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8 views

Extracting times of hits from a composite detector response

I have a detector that registers a sequence of "hits" over a period of time. Each hit produces a signal that has the approximate form ...
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42 views

No length contraction!

Suppose a person standing on a platform were to observe and measure the length of a train passing by. Instead of the usual approach involving a clock and knowing the speed of the train, the person ...
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23 views

Maximum error of number of observations within several certain intervals – Accuracy of variable is known

I have carried out a series of measurements of different thermal comfort parameters from which I have calculated another variable called PMV. My data set consists of hourly measurements (and ...
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22 views

Uniqueness of representing POVM using projective measurement

$\newcommand\tr{\operatorname{tr}} \newcommand\ket[1]{\lvert#1\rangle} \newcommand\bra[1]{\langle#1\rvert} $[Skip to the conjecture for a self-contained mathematical formulation of the question.] ...
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17 views

For thermal mass flow measurement technologies is it necessary to measure gas pressure to determine volumetric flow rate?

Mass flow readings from thermal mass flow measurement technologies often provide output readings in volumetric units (e.g. standard liters per minute). Mathematically I can derive the volumetric flow ...
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2answers
37 views

Does measuring the air temperature near a 21 lane asphalt highway impact measurements?

The official temperature in Sydney is measured at the Sydney Observatory. This is located near the city side of the Sydney Harbour Bridge - which is a major highway. My question is Does ...
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1answer
40 views

Frictionless Cart on a Ramp (Experimental Design Question)

Question: Why is the calculated value for our final velocity higher than our predicted value? Since our prediction neglected air resistance and friction, shouldn't the velocity for the actual cart ...
3
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1answer
61 views

How do we perform transverse measurements in a two level system?

In quantum mechanics any two level system can be mapped onto effective spin variables. If the system is defined by two energy levels, $|E_1\rangle$ and $|E_2\rangle$, the Hamiltonian is $$ H = ...
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3answers
41 views

How can I measure the speed of a figure skater's spin?

My daughter is a figure skater and needs to measure how fast she is spinning before she loses her position. This is a science project for 7th grade. I have looked for devices to possibly measure her ...
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2answers
109 views

How can you accurately determine your own mass?

I'm trying to figure out whether it is possible for an individual to accurately determine his/her own mass, to within 100g, using equipment that is readily accessible or can be purchased at a ...
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2answers
125 views

How should I quote errors when measurements are asymetrically clustered?

Suppose five people measure the length of a stick and report the following values 4.90cm 4.92cm 4.93cm 4.94cm 4.94cm In high school science we are told that in ...
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23 views

Is there a way to measure the energy stored in a twisted rubber band?

I am building an energy storage device using rubber bands. It contains 24 bands which are twisted by a set of gears. I would like to measure (or predict) the amount of energy that the device can ...
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2answers
68 views

can one measure energy to a finite accuracy?

Can one measure energy to a finite accuracy in bounded amount of time? I don't know much about QM, but someone told me that the energy-time uncertainty principle says that it would take infinite ...
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2answers
47 views

U.S. Standard Atmosphere

My textbook states that "Ideally, we would like to have measurements of pressure versus altitude over the specific range for the specific conditions (temperature, reference pressure) for which the ...
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1answer
52 views

Thought Experiment: Force on magnets in a Stern Gerlach Experiment

Background: In the SG experiment, an inhomogenous magnetic field affects a force on particles passing between two magnets. "Measurement" takes place when a screen is placed on one end, blocking one ...
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1answer
76 views

Is it possible to determine whether distant galaxies are gravitationally bound

In a previous question, one issue was related to the potential energy of cosmic structures. This raised in particular the question of whether these structures are gravitationally bound. If you ...
2
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1answer
50 views

Measuring more accurately the distance of remote galaxies

From what I read in Wikipedia, the velocity of a Galaxy has two components: one is due to Hubble's law for cosmic expansion, and the other is the peculiar velocity of the galaxy. Since the peculiar ...
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2answers
271 views

What is the spin of an electron along the x-axis?

I know that an electron or any other particle for that matter, has a measured spin which is either up or down. This spin is along the z-axis. But what if we do not measure it along the z-axis and do ...
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0answers
35 views

How many measurements of a physical quantity should you do to get a representative value / distribution? [closed]

When we measure a physical quantity multiple times, we can calculate several values which should help us understand the whole measurement better: Standard deviation, variance, median, average, and so ...
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1answer
45 views

How and under what principle are measurements made at quantum level? [closed]

There's a lot of news about amazing quantum phenomena, but even without the expert knowledge I would still like to know how it is done and think about the possibility of errors in measurements. How, ...
2
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1answer
66 views

What was a second in the early universe?

I have read some popsci articles and documentaries about the early universe and they often explain how various features of the universe came about and at what time. For example hydrogen atoms came ...
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3answers
111 views

Scalable quantum computation vs Uncertainty Principle

tl;dr. : If we want the result of a quantum computation to have scalable more bits, we will need inner measurements to have scalable precision, if we already know the result of the computation (from a ...
2
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3answers
102 views

Measuring position and momentum at the same time?

In a non-relativistic quantum mechanical system in an infinite potential well. I try to measure the energy and the position of the system simultaneously. Since, the respective operators do commute ...
4
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1answer
61 views

What does a MEMS gyro measure during off-axis rotations?

I've been working with MEMS gyroscopes in hobbyist projects for years—but it's recently come to my attention that I don't have any principled understanding of what rotation rate measurements ...
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2answers
60 views

How is photon time of flight/range over sub-millimeter distances measured?

I was reading a paper that described how the force a low-thrust torsion pendulum was measured. In it, the paper states a laser is bounced off a mirror and the displacement is "...based upon the beam ...
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2answers
54 views

About time measurements

What we regard as TIME is just a way of measuring duration for various phenomena. Like a ruler is a measuring device for measuring length ( or breadth or width). Saying Time is an illusion is like ...
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1answer
26 views

How can I ensure my scale is not affected my surface beneath it

I have person weighing spring scale. I live in Japan where the house has wood floors which deflect significantly under weight. I weighed my self in the bathroom and in the tiled bath area. The ...
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2answers
156 views

A question about atomic clocks

I have a rather simple question about atomic clocks. I have read that: Microwave radiation with a frequency of exactly 9.192.631.770 cycles per second causes the outermost electron of cesium-133 ...
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1answer
101 views

How to measure Entropy?

While $$\delta Q=T\ dS$$ allows for obtaining the entropy change of an isolated system in equilibrium by measuring the heat exchange with the environment, I was wondering whether there are ways to ...
2
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2answers
81 views

Can the magnetic fields of EM radiation be harnessed or measured?

We use the electric component of EM radiation to create the EM radiation and to detect it (antennas and Etc.), but does anyone know of a situation where the magnetic component of EM radiation is used? ...
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2answers
33 views

How to measure rainfall? And how is it determined for a specific location?

How is rainfall measure in a pinpoint location? This is what I think: There are automatic rainfall measuring stations at: A, B, C. But say I want to know point D, located between A and B, its ...
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3answers
160 views

Is a “shift in the meaning” of Accuracy and Precision occurring?

Accuracy and precision are among the most fundamental concepts in experimental physics, and, I always believed, completely unambiguous. Recently I found that the Wikipedia article on Accuracy and ...
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3answers
55 views

Can we measure rates in real time?

I know what it means to say that my position is "X" at a particular moment in time. I can easily take a picture of my motion and observe my exact location at the instant the picture was taken. That is ...
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3answers
70 views

The measurement of electricity

I'm a student trying to understand electricity. As I learned from school, electricity is the flow of electrons, but I'm confused about the measurement of electricity. As I learned, voltage is the ...
4
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1answer
40 views

Can we directly measure vectors' quantities?

Can we perform some kind of experiment that will give us, for example, the $p_x$, $p_y$ and $p_z$ of a particle in a single measurement? I'm aware that they commute so one measurement will not ...
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2answers
127 views

How can we measure time?

If we cannot define a proper time (or synchronize clocks in different positions) in an inertial frame (independent with the theory of relativity), there seems to be no direct way to confirm the 2 ...
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5answers
436 views

Uncertainty principle with two photons

Imagine an experimental setup in which you have to measure the momentum and location of a particle. To measure it we know we will have to affect it, and the uncertainty principle would come into the ...
3
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1answer
62 views

Measuring Atomic Radius of a Noble Gas

How exactly can you measure the atomic radius of a noble gas such as Neon or Helium accurately? Would liquefaction help? I also heard that the aforementioned gases are the only common elements which ...
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18 views

Contact resistance copper-silver

I need to determine the contact resistance of a copper silver interface. The copper wire was soldered to the substrate using an IR-Laser. I was wondering if I can treat the entire system as a series ...
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2answers
118 views

How can Lorentz contraction be “directly” measured?

If one is watching a relativistic object of e.g. spherical shape, which emits enough light to be detectable, it will, despite being Lorentz contracted, appear of its natural shape, although rotated. ...
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1answer
56 views

How stellar aberration is measured?

A simple calculation shows that stellar aberration due orbital motion of earth is roughly 20 arcseconds. My questions are: Practically how this small value is measured? Does this value is in the ...
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2answers
56 views

Accelerometer validation trace

I am attempting to validate an accelerometer. I have a triaxial accelerometer and placed it on a wheel which goes at various frequencies from 1 to 3 Hz. Am I right in thinking that I would expect the ...
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2answers
65 views

How to use an accelerometer to correctly quantify the magnitude of vibrations

Consider the following setup, an accelerometer is placed inside a helicopter, measuring "g" values along 3 axes (x,y,z) every 10 ms (100 times a second), during a helicopter flight. If one, wants to ...
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4answers
111 views

Equations of graphs

I am doing a practical write up of an experiment I did. Here is a graph using the raw data I got. What is the general formula of this graph, and what do I need to do in order to make that into a ...
16
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1answer
921 views

Is the Uncertainty Principle valid for information about the past?

My layman understanding of the Uncertainty Principle is that you can't determine the both the position and momentum of a particle at the same point in time, because measuring one variable changes the ...
4
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2answers
357 views

What is the duration of a snap?

What is the duration of a snap (of the fingers)? When someone says, "it's ridiculously fast, it's like [snap]" - where [snap] is them snapping their fingers - they would normally mean it is ...
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1answer
74 views

Plasma Question: Expression for electron temperature in terms of the voltage of each prong of a triple Langmuir probe?

So I am trying to derive an expression for electron temperature based on the voltages on a triple Langmuir probe. I have pretty much been following the triple Langmuir probe derivation on wikipedia ...
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1answer
53 views

Combining ±% with ±dB in measurement uncertainty

Firstly apologies if this is not the correct place to post this but wasn't sure which site would be good to ask regarding about measurement uncertainty calculation. I am trying to calculate the ...
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22 views

Cosmic ray noise, strategic cancellation

With the radio telescopes, we measure the radio waves produced by every solar fluctuation in the near universe, which as I understand is heard similar to radio static we experience in tuning to a non ...
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66 views

How to specify BRDF measurement

As a person who will be using the scattering measurement results (in Zemax), I was asked to prepare the specs for the BRDF measurement. However I've never done it until now, so help would be greatly ...