# Tag Info

0

The speed of light is invariable but the number or ratio of the frames of reference are variable as determined by the amount of gravity, the result of which is gravitational lensing.

3

In theory there is no lower limit on the amount of energy that must be exchanged to make a measurement, at least directly. But you are constrained by Landauer's principle when you initialize the memory you need to record the measurement. Effectively the measurement is the replication of information about the measured system's state in the measurement system'...

9

You cut off the sentence that tells you what the numbers mean. "All uncertainties define a 90% credible interval". Crudely speaking, it means that there is a 90% probability of the parameters lying in the quoted range, with the most likely estimate being the headline number. It doesn't really make sense to translate these into Gaussian sigmas (it would be ...

4

The phase ambiguity is a bit worse than you think. There is a global phase ambiguity in $|\Psi⟩$, for sure, but if the state $$|\Psi⟩=\sum_n c_n |\alpha_n⟩ \tag 1$$ is all you have around, then there is also a phase ambiguity in the phase of each individual $c_n$. This is because if you change $|\alpha_n⟩$ to $|\alpha'_n⟩=e^{i\theta_n}|\alpha_n⟩$, the ...

0

There are essentially two ways in which we obtain functions and models ourselves: through the use of an appropriate measuring instrument (ruler, protractor, scale, clock...) or via mathematical logic. Measuring instruments can give us an excellent but imperfect approximation, while mathematical logic provides us an exact value based upon input values that ...

2

[Note: answer completely updated] Based on your SEM picture and the further explanation in the comments, it seems that your system looks like this: You have materials A and B that form the thermocouple pair, a bead of mixture "AB" as a junction. The bead is embedded in and fused with a substrate material "C". A further complication is that there is a ...

2

The least count of the watch used for the measurement of time period is $0.01$ s This information is just telling you to round off to the second decimal place, as you correctly did. The sample mean is $\mu = 0.56$ and the sample standard deviation is $\sigma = 0.02$. The answer the text is referring to is $$\frac \sigma \mu = 0.0357 = 3.57 \%$$ But I ...

2

I think you are confusing systematic and random errors. Your experimental results can give you no idea about the systematic error. For example it might be that your timing device is calibrated incorrectly and when the correct time is 1.00 seconds then your timing device gives a reading of 1.10 seconds; when the correct time is 2.00 seconds the timing device ...

3

This is done in several papers, e.g. here: http://cds.cern.ch/record/546624/files/0204052.pdf The relevant portion is Lemma 1. Given a state $\rho$ with covariance matrix in block form $$\gamma_{\rho}=\begin{pmatrix}{} A & B \\ B^T & C \end{pmatrix}$$ the covariance matrix after a measurement after a projection onto the pure Gaussian state with ...

0

Direct measurement of the amplitude of the optical field requires interferometric techniques. One that works is the FROG - Frequency Resolved Optical Grating. There are many variations on it today, including from the original developers: Trebino Research Group. These devices were designed for ultrafast pulses. For CW one usually just measures intensity ...

0

To me, using the distance to measure 2 dimensional data is dubious, especially if the events are near to the reconstructed position (supposed 0 distance). Say if the events form a circle (the circle is perfect gaussian). The distribution will not be anymore gaussian since the blue area (in the drawing) will be lesser than the yellow:

1

As explained in the comments, for a given MC event, the errors $\delta x$ and $\delta y$ for the two reconstruction methods A1 and A2 are uncorrelated. Therefore, no extra information is gained by using both reconstructions. We should just use the better one. Now, what does "better" mean. As stated in the OP, for both reconstructions, the distributions of \$\...

0

Voltage is the electric potential. As already pointed out by ticster, it is analogous to the gravitational potential, which can be intuited as the height of a hill on earth (higher points having higher gravitational potential). We all know that balls on a smooth hill tend to move toward the bottom. In the case of a ball on a hill, you might also ask, how ...

0

Electricity is not flow of electrons, it is the flow of charge which can be positive or negative. When books tell us that electricity is flow of electrons, they are merely talking about conductors or alloys where only electrons can flow as protons are too heavy to flow. Voltage or the potential difference is generally electric pressure or electric potential....

Top 50 recent answers are included