The measurement tag has no wiki summary.
28
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13answers
7k views
Home experiments to derive the speed of light?
Are there any experiments I can do to derive the speed of light with only common household tools?
3
votes
2answers
205 views
Measuring extra-dimensions
I have read and heard in a number of places that extra dimension might be as big as $x$ mm. What I'm wondering is the following:
How is length assigned to these extra dimensions?
I mean you can ...
16
votes
5answers
2k views
What if the universe is rotating as a whole?
Suppose in the milliseconds after the big bang the cosmic egg had aquired some large angular momentum. As it expanded, keeping the momentum constant (not external forces) the rate of rotation would ...
3
votes
1answer
843 views
How to combine the error of two independent measurements of the same quantity?
I have measured $k_1$ and $k_2$ in two measurements and then I calculated $\Delta k_1$ and $\Delta k_2$. Now I want to calculate $k$ and $\Delta k$.
$k$ is just the mean of $k_1$ and $k_2$. I thought ...
3
votes
1answer
364 views
About binary stars and calculating velocity, period and radius of their orbit
I saw somewhere about being able to measure the velocity, period and radius of a binary star orbit by looking at red shift and blue shift.
I understand it but can someone give me an example of ...
10
votes
4answers
652 views
Energy Measurements in a Two Fermion Double Well System
This question is related but my question here is much more elementary than discussions of the Pauli principle across the universe.
There has been a fair amount of discussion around at the moment on ...
1
vote
1answer
144 views
Photometer: measured Irradiance L converted to photon rate
I am conducting an experiment in which the power meter reading of $410\,nm$ narrow bandpass stimulus is noted to be 30 $\frac{\mu W}{cm^2}$ at a distance of 1 inch away from the light source.
I wish ...
4
votes
4answers
649 views
Measuring the speed of light and defining the metre - absolute or relative?
If the metre is now defined as the distance light travels in vacuum in 1⁄299,792,458th of a second and the speed of light is accepted to be ...
3
votes
1answer
174 views
Quantum Zeno effect and unstable particles
Is it possible to increase indefinitely the lifetime of unstable particles by applying the quantum Zeno effect? Is there a bound from theoretical principles about the maximum extension one can get in ...
16
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1answer
1k views
How did they measure the speed of light observing Jupiter's moons, centuries ago?
I am interested in the pratical method and I like to discover
if it is cheap enough to be done as an experiment in a high school.
Thank you.
3
votes
11answers
749 views
Is it possible for a physical object to have a irrational length?
Suppose I have a caliper that is infinitely precise. Also suppose that this caliper returns not a number, but rather whether the precise length is rational or irrational.
If I were to use this ...
8
votes
3answers
523 views
How hot is the water in the pot?
Question: How hot is the water in the pot? More precisely speaking, how can I get a temperature of the water as a function of time a priori?
Background & My attempt: Recently I started spend ...
5
votes
3answers
844 views
How to combine measurement error with statistic error
We have to measure a period of an oscillation. We are to take the time it takes for 50 oscillations multiple times.
I know that I will have a $\Delta t = 0.1 \, \mathrm s$ because of my reaction ...
4
votes
10answers
1k views
What is the wavefunction of the observer himself?
I am aware about different interpretations of quantum mechanics out there but would mostly like to see an answer from the perspective of Copenhagen interpretation (or relative quantum mechanics if you ...
2
votes
3answers
772 views
What is the velocity area method for estimating the flow of water?
Can anyone explain to me what the Velocity Area method for measuring river or water flow is?
My guess is that the product of the cross sectional area and the velocity of water flowing in a pipe is ...
4
votes
3answers
112 views
Precision of Coulomb's law
Up to which precision has the coulomb law proven to be true?
I.e. if you have two electrons in a vacuum chamber, 5 meters appart, have the third order terms been ruled out? Are there any theoretical ...
1
vote
1answer
293 views
Measuring the magnitude of the magnetic field of a single electron due to its spin
Is it possible to measure the magnitude of the magnetic field of a single electron due to its spin? The electron's intrinsic magnetic field is not dependent upon the amount of energy it has does it? ...
7
votes
0answers
103 views
Why is the Planck length the shortest measurable length? [duplicate]
I quote from the Wikipedia article on Planck length:
According to the generalized uncertainty principle, the Planck length
is in principle, within a factor of order unity, the shortest
...
2
votes
1answer
82 views
Basic question about probability and measurements
Say I have a Galton box, i.e. a ball dropping on a row of solid bodies. Now I want to calculate the probability distribution of the movement of the ball based on the properties of the body (case A). ...
2
votes
1answer
408 views
How much water must flow trough canal to maintain a constant water deep?
In order to maintain a constant water deep in canal, how much water must flow trought the pipe ?
As shown on picture, canal have a rectangular shape.
I don't know if canal length have an influence.
...
2
votes
1answer
224 views
Is $\sigma$ or $\sigma / \sqrt{N}$ is error of a measurement?
I wonder whether $\sigma$ or $\sigma / \sqrt{N}$ is error of a measurement. When I measure, say $0, 1, -1, 1, -1$, I have a $\sigma = 1$. I just measure $0, 1, -1$, I also have $\sigma = 1$.
But in ...
1
vote
4answers
483 views
How to describe a well defined “zero moment” in time
Suppose you have to specify the moment in time when a given event occurred, a "zero time". The record must be accurate to the minute, and be obtainable even after thousands of years. All the measures ...
