Mean Definition and 1000 Threads

There we read: "note that if Wigner did not know this phase due to the lack of control of it, he would describe the “spin + friend’s laboratory” in an incoherent mixture of the two possibilities". Why is this the case? Given that the author has propoede neither a citation nor a proof for this...

Suppose that in Copenhagen, we measure one of the eigenvectors/eigenvalues ##e_x##, the outcome being ##M_x##. Now, in MWI, micro-outcome ##e_x## gets entangled with macro-outcome ##M_x##, right? So, what does that mean in this case? If all outcomes are realized, should outcomes ##e_n## resp...

Summary:: Comparing education systems from different countries. ..our education system is easier? Or does that mean our material is tougher and the grading system balances out? Or is just cultural differences. The only exception is York. It doesn't like (-) so an 80 is just an A. 90+ is an A+.

For the first question, i believe that mechanical energy is conserved hence we can derive the total energy i think. In regards to the second question, I'm assuming its at room temperature, so helium is monotonic therefore it has 3 degrees of freedom, therefore its internal energy is 3/2KT. I am...

Physicist Joseph Polchinski wrote an article (https://arxiv.org/pdf/1412.5704.pdf) where he considered the possibility that all symmetries in nature may not be fundamental. He says at page 36: "From more theoretical points of view, string theory appears to allow no exact global symmetries, and...

We usually think about atomic orbital as wave(function), but it was created from e.g. electron and proton approaching ~10^-10m (or much more for Rydberg atoms), and electron has associated electric field. This wavefunction also describes probability distribution for finding electron (confirmed...

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Hi, I was just thinking about different ways to use the Fourier transform in other areas of mathematics. I am not sure whether this is the correct forum, but it is related to probability so I thought I ought to put it here. Question: Is the following method an appropriate way to calculate the...

Suppose P(B|A)=1. Does that mean that P(A|B)=1?

I am not sure about how to approach this. Since the volume is uniformly distributed, the mean volume is ##(5.7+5.1)/2=5.4##, which is less than ##5.5##. From this, I could say that, on average, the producer won't spend any extra dollars. But then I thought that maybe I should interpret this as...

I'm just starting my undergraduate Quantum Mechanics course. I had a homework problem to show that \Delta S_x = \sqrt{\langle S_x^2 \rangle - \langle S_x \rangle ^2} = 0 , S_x being the spin in the x direction. I managed to solve it, but the physical interpretation is confusing me. If I...

Suppose I had a Lagrangian $$L = q+ \dot{q}^2 + t.$$ This has explicit time dependence. Now consider another Lagrangian: $$L = q+ \dot{q}^2 .$$ Which has no explicit time dependence. But after solving for the equations of motion, I get $$\dot{q} = t/2 + C.$$ So I could now write my Lagrangian...

Quote 1: "[He] accumulated an estimated 30,000 volts of static charge simply by walking around his home town in inadvisably large quantities of non-natural tailoring." Quote 2: "A man left a trail of scorched carpet and melted plastic after static on his clothes built up to a 40,000 volt...

what means unit j.s in plank constant As Planck's constant is the smallest unit of energy so what this unit j.s

I used the form of the mean free path equation taking advantage of the fact that the Boltzmann constant is equal to the ideal gas constant R divided by Avogadro's number, because I didn't know if I could use the Boltzmann constant in the ##1.381\cdot 10^{-23}J/(molecules\cdot K)## form...

If neutrinos are majorana particles does this mean that lepton number is not conserved in particle reactions? And I only noticed neutrinos are only produced when the decay of a particle to some other particles is carried by the W bosons ( weak interaction ). Is it possible the weak interaction...

This question came in NEET Exam 2018.Now my first query is that in the question,the mass of one Oxygen molecule is given wrong.Its exactly half it's true value.I don't think anybody has noticed this before because I couldn't find any change in the printed question on so many different books...

So I have always been thinking that equilibrium means that an object is not moving or having constant acceleration. On a webside they said: " A rigid body is in equilibrium when it is not undergoing a change in rotational or translational motion. " To me it sounds like the object then must not...

I come across the adjective 'comoving' quite often. I understand comoving coordinates for the Universe. They are coordinates which expand with the expansion of the Universe(?) but I'm confused about what it means in essence. Here are some examples: In Sean Carrol's book there is a question...

Hi all, The killing vector equation reads: ##\nabla_{(\mu K_{\nu})} = 0## What do the parenthesis mean explicitly? Moreover, I know that ##\nabla_\mu x^\nu = \partial_\mu x^\nu+ \Gamma_{\rho \mu}^\nu x^\rho## So if the parentheses mean symmetric the Killing equation will read...

I read in one book proving one nature of variation(variation of high-order derivative). It writes that "##\delta(F^{(n)}) = F^{(n)} - F_0^{(n)} = (F - F_0)^{(n)} = (\delta F)^{(n)}##". But I don't understand where this ##F_0## comes out from.

Homework Statement:: What does the following quote by Mathematician Paul R. Halmos mean? "The only way to learn mathematics is to do mathematics." Relevant Equations:: What dose he mean by "doing mathematics"? Is it solving puzzles or studying theorams or reading about mathematics? Thanks

I found the correct solution using the equation that relates force and pressure, but I don't REALLY understand what the question is asking and what is actually going on in the machine. I want a better understanding of everything that's going on, not just an answer. Below is a clear diagram and a...

My lecturer said it means: "3rd residue, C-terminal to Helix 'H'" but that makes no sense. If it's the 3rd residue then it can't be on the C-terminal, because the C-terminal is at the end of a massively long sequence of residues. Visa versa if it's on the C-terminal then it can't be the 3rd...

This is on page 2, and I guess it is the key to understanding what they mean by linearized perturbation to a BH in the abstract. What is meant by gravitational fields, what is delta(g_ab) and delta\Phi ? A perturbation to the metric, and the 'gravitational field', sure. And where are these...

First calculate mean velocity: 400 hl h-1 = 40,000 L / h-1 = 666.67 L/min 1L/min = 10^ -3 m3/min 666.67 L/min = 0.666 m3/min = 0.0111 m3/sec Cross sec area = (3.14)(0.1/2)^2 = 7.853 x 10^-3 m2 0.0111/7.853 x 10^-3 = 1.413 m/s Re = (1010)(1.413)(0.05)/0.0025 = 28,542.6 Am i right here? Re...

I know that being intolerant makes it so that my stomach doesn't digest milk/dairy products very well. I get gas and diarrhea at times. But, would it also mean that when I eat something with dairy that my body does not digest the nutrition in it (as it may be "kicking" it out of my body...or...

I am following this: avntraining.hartrao.ac.za/images/Error_Analysis.pdf I have a ruler with an uncertainty of ± 0.5mm. I made a calculation subtracting one measurement of the ruler, from another measurement, making the uncertainty for the data ± 1.0mm. As I have four trials, I calculated the...

I know m isn't matter; it's inertial mass, but I don't know what that means or how it "equals" energy. I've never found an explanation I understood, so I thought I'd try asking here. Matter can be converted to energy, though, right? That's how nuclear bombs work, or hydrogen bombs...my...

$10 min = \dfrac{h}{6}$ So $a(t)=v'(t) =\dfrac{\dfrac{(50-30)mi}{h}}{\dfrac{h}{6}} =\dfrac{20 mi}{h}\cdot\dfrac{6}{h}=\dfrac{120 mi}{h^2}$ Hopefully 🕶

Hello, looking to find out what the term "10000 units per 15 min (quick reduction)" from the WHO means in terms of using heat to kill a virus.

Ok Just have trouble getting this without a function..

$\tiny{3.2.15}$ Find the number c that satisfies the conclusion of the Mean Value Theorem on the given interval. Graph the function the secant line through the endpoints, and the tangent line at $(c,f(c))$. $f(x)=\sqrt{x} \quad [0,4]$ Are the secant line and the tangent line parallel...

I'm confused about how to find the final value of g and its uncertainty. I've done a bit of research and I have encountered conflicting information, some say you have to weight the measurements, some say you have to find the standard deviation then divide by two, etc. I have the following...

In this problem what does ' a distance L apart ' mean ?A –2.0 μC point charge and a 4.0 μC point charge are a distance Lapart. Where should a third point charge be placed so that the electric force on that third charge is zero?

import numpy as np a=np.array([[1,2,3], [4,5,6]]) print(s) print() print(a.mean()) I know how to take the mean of the entire array. However I am having trouble understanding what it means to subtract the mean from each column. Does this mean subtract it from each element in the column? Thank...

This just occurred to me and I don't expect to be the first one to address it: It is said that in a specific measurement basis, the outcome of a measurement in this basis is determined by chance. But in how far is this the case, since if the eigenvectors are for example ##\overrightarrow{A}##...

I have been reading about the "greenhouse effect" of Earth's atmosphere, having been conscious that while I generally understand it I had never really examined it more closely. A problem that bothers me is mention of "surface temperature" which seems to vary according to context. In some...

It seems that the word ontology which suppose to be about the most concrete object we can come up with is itself not well defined. Take for example this post Which alludes to primitive ontology as a property and not "what" is actually there(ontology proper) as the ultimate ontology which we...

Could someone provide me with the intuitive understanding of state of a thermodynamic system? What does state variables/parameters mean?

a) Proof: By theorem above, there exists a ##a \in \mathbb{R}## such that for all ##x \in I## we have ##f'(x) = a##. Let ##x, y \in I##. Then, by Mean Value Theorem, $$a = \frac{f(x) - f(y)}{x - y}$$ This can be rewritten as ##f(x) = ax - ay + f(y)##. Now, let ##g(y) = -ay + f(y)##. Then...

I was reading about this https://en.wikipedia.org/wiki/Nitrogen_laser and it says "80 to 100 eV per Torr*cm pressure of nitrogen gas". I'm finding this a little bit confusing. It needs some specific amount of energy in a centimeter of volume with 1 Torr of pressure?

The expression I have found is this one. https://ibb.co/kqG24L3 I have been looking for information because I could not to realize what is the value that "alpha" has to have. If any of you do know what this alpha value is supposed to represent or if you have seen it before I would be really...

What feature of the equations of classical physics show that space and time are fundamental and how would the equations differ if space and time were not fundamental but emergent? I heard all of this from a previous talk and I would appreciate any help and any further reading recommendations.

Hello, I'm newly discovering the world of the Energy. My question is about the equation ##U=\int \vec{F}\times d\vec{r}=-\int \vec{F}_{s}\times d\vec{r}##. Can you tell me what does this equation means? Thanks!

Let f be a function twice-differentiable function defined on [0, 1] such that f(0)=0, f′(0)=0, and f(1)=0. (a) Explain why there is a point c1 in (0,1) such that f′(c1) = 0. (b) Explain why there is a point c2 in (0,c1) such that f′′(c2) = 0. If you use a major theorem, then cite the theorem...

The arrival of quantum computing reminds me of "the manhattan project" and "the sputnik alert" when physicists are highly demanded. And this makes me wonder if the age of quantum computing means the better future for physicists since the development of quantum computers needs at least...

I am reading "Complex Analysis for Mathematics and Engineering" by John H. Mathews and Russel W. Howell (M&H) [Fifth Edition] ... ... I am focused on Section 3.2 The Cauchy Riemann Equations ... I need help in fully understanding the Proof of Theorem 3.4 ...The start of Theorem 3.4 and its...

Summary: If the furthest quasars we can see are let's say 13 billion light years away from us, then does this mean that the distance between us and that quasar was 13 billion light years at 13 billion years ago? To anyone educated in physics this might be a silly question but to me this is...

Hello This is a really silly question but I have doubted myself and I was wondering if anyone could help. I have been given the following information:-I am trying to understand what it means when the title states Unit Weights? I thought these were density but density is kg/m^3 - whereas these...