Local Definition and 491 Threads

First, create a rocket ship with: * a clock * a 3-axis accelerometer * a computer * a 3-axis external thruster The rocketeer begins in Earth orbit and sets the clock to Earth time. Then the ship takes off on a random trip through our universe. The pilot will arbitrarily point and apply the...

' Finally, if we care only about long distances, the effective action should be a local functional, meaning that we can write is as ##S_{eff}[A]=\int d^d x...## ' Where does this come from and what does it mean? This isn't at all familiar with me, and I don't recall ever seeing anything...

I see many posts by several different people referring to spacetime being "locally flat" with the intended meaning of being locally indistinguishable from Minkowski space, i.e., being able to rewrite the metric on orthonormal form and not being able to measure curvature on some local scale. I do...

Hi. Could the local effects of gravity between nearby stars at the edge of a galaxy cause these stars to rotate around the centre of the galaxy more quickly than predicted if the prediction is based upon individual stars only. This effect would be similar to the way the Earth "drags" the Moon...

Interesting paper on the arXiv today. The authors claim that there is observational evidence that we live in a region with slightly lower density than the universe average, just by chance. Taking this into account can explain as much as 5.5% of the discrepancy in the Hubble constant between...

Consider a pair of entangled particles described by a local theory without hidden variables. Because there are no hidden variables, the results of an experiment on one particle of the entangled pair must be perfectly random. Due to locality, the particles also have no way of coordinating the...

What I understand is, I have written something like this myself. What is a Static Proxy and a Dynamic Proxy then? Also, What is a Transient Proxy and a Persistent Proxy?

What I can't understand from the problem is that whether she stays at a certain pub for M hours, or she visits more pubs and goes home after M hours. If it's the first case, then I think the answer is ##\frac{M}{24}\frac{1}{N}##. This problem is posted as a harder one so I suppose it has to...

Hi everyone, I'm struggling with this problem: Let ##f(x,y) = \begin{cases} (x-y)\ln(y-x) & \text{if } y>x \\ 0 & \text{if } y\leq x \end{cases}## and let ##C=\{(x,y)\in \mathbb{R}^2|x^2+y^2=1\}## Then proof that ##max_Cf=1/e## and ##min_Cf=-(\ln2)/\sqrt2## My solution: I used Lagrange...

Homework Statement I set the derivative to 0. i get 1 real root a max point and 2 imaginary. How can i find that local min? what techniques are available?

Homework Statement Let ##f:\Bbb{R} \to \Bbb{R}## be a function such that ##f## has a local minimum for all ##x \in \Bbb{R}## (This means that for each ##x \in \Bbb{R}## there is an ##\epsilon \gt 0## where if ##\vert x-t\vert \lt \epsilon## then ##f(x) \leq f(t)##.). Then the image of ##f## is...

Yes I've already looked on SO! None of the answers contain the word "may". My story is that I am passing in references to global variables, modifying them, and returning them in array literals. I suppose it must complaining about the array literals (c99) rather than the variables themselves...

I've decided to return to my local community college this coming fall. I'm going to major in Physics with a concentration/intention to go into engineering with it. There aren't that many information technology/computer science/entry level helpdesk job postings where I live. On Indeed.com...

Hi, I have an interview at one of my local phone companies for a tech, internet helpdesk 1 position (something that I'm qualified for) (I'm trying to get out of dishwashing ASAP for obvious reasons). There's paid training both in classroom and hands on. It's a full time position. I'm attending...

Not sure if this reference has been posted yet, but I just saw it come through and thought I'd share. This is the "Big Bell Test Collaboration" using measurement choices provided by persons (as opposed to computer generated "random" choices). (The authors are a virtual who's who in the world...

[Moderator's note: Spun off from another thread due to topic change.] Can I say that "being at rest in a uniform gravitational field is locally equivalent to accelerating in flat spacetime, free falling in a uniform gravitational field is locally equivalent to nonacceleration in flat spacetime ?"

The question is whether or not expansion in flat, matter-only universes (no lambda) has any effect whatsoever - no matter how negligible - on dynamics of small-scale systems. Context: It's a variation on the 'is Brooklyn expanding?' type of questions. My understanding has always been that...

Non-philosophically inclined experts in relativistic QFT often insist that QFT is a local theory. They are not impressed much by arguments that quantum theory is non-local because such arguments typically rest on philosophical notions such as ontology, reality, hidden variables, or the...

Hi All, For the attached question, I think that substituting theta = 0, I get the Euler method back. If I substitute theta = 1/2, I get the Crank-Nicholson (Modified Euler) method back. In terms of accuracy, I know this means that Crank-Nicholson is the more accurate method. I am mostly...

I've been playing around a bit with the Kerr orbit program I wrote, and have been thinking about ways to set the initial conditions. One thing I'd like to be able to do is specify a launch from some event in terms that would be convenient for an observer at that event with some given...

It occurs to me that it might be possible to determine a local value of G by observing the tides over a long-ish period. Tide height might be distributed as a normal curve, but it might have a measurable deviance. I wouldn't expect a left/right offset of the X coordinate based on G(local) , but...

What is wrong with the idea that the spooky correlation in the EPR experiment is simply the result of the initial difference in rotation between the two polarizers in this experiment? So if you rotate one of the polarizers relative to the other polarizer, that initial act of rotation is what...

The interactive model can be found at: Action Dynamics of the Local Supercluster Interactive Model Source: Action Dynamics of the Local Supercluster - The Astrophysical Journal, Volume 850, Number 2, December 2017 (free preprint)

$\tiny{243.14.7.5}$ $\textsf{Find all local extreme values of the given function and identify each}$ $\textsf{as a local maximum,local minimum,or saddlepoint}$ $\textit{$f$ has a} \textbf{ saddle point } \textit{at $(a,b)$ if}$ \begin{align*} \displaystyle f_{xx}f_{yy}-fxy^2&\ge 0 \text{ at }...

$\tiny{243.14.7.4}$ Find all local extreme values of the given function and identify each as a local maximum,local minimum,or saddlepoint \begin{align*} \displaystyle f_4(x,y)&=x^2+14x+y^2-12y+5\\ \end{align*} saw this in the section $\text{if we substitute the values} \\$ $\text{$f_xCa, b) =...

In Hartree-Fock method, I saw the Fock operator has two integrals: Coulomb integral and exchange integral. One can define two operator. "The exchange operator is no local operator" why? Whats de diference: local and no local operator? And why do the operators have singularities? thanks

Homework Statement Homework Equations At local minimum or maximum the first derivative equals zero The Attempt at a Solution a) $$f'=2x-\frac{a}{x^2},~~2\cdot 2-\frac{a}{4}=0~\rightarrow a=16$$ Near 0 from the left a/x gets large negative values, smaller than for a=16. that's my proof for...

Homework Statement Let ##X## and ##Y## be topological spaces, and let ##\{U_i\}## be a collection of open sets in ##X##. If ##X = \bigcup U_i## and ##f|_{U_i}## is continuous, then ##f : X \to Y## continuous. Homework EquationsThe Attempt at a Solution Let ##x \in X##, and let ##V \subseteq...

We are always taught in books that a Lorentz transformation is possible as long as the Lorentz matrices ##\Lambda## in ##\vec{x}{\ }' = \Lambda \vec{x}## are not function of ##\vec{x}##. The reason for this is obvious, since in this way the relation ##t^2 - x^2 - y^2 - z^2 = t'^2 - x'^2 - y'^2...

Breaking of a local symmetry is impossible. It is often said that therefore the role of the Higgs mechanism in the standard model is a different one. Namely, Once a gauge is fixed, however, to remove the redundant degrees of freedom, the remaining (discrete!) global symmetry may undergo...

I propose for your consideration the following version of this experiment: We have a source, S that produce pairs of spin 1/2 entangled particles and two detectors, A and B that measure the spin of those particles. The detectors are oriented on the same direction, say X and they are fixed. As...

With E a,b = ( dλ ( a,a' b,b' λ) Suppose λ depends independently/locally on detector setting choices at A and B. For example suppose there are 360 detector settings at A and 360 at B , corresponding to 360 particle/detector interactions/outcomes at A = ± 1 and also at B = ± 1. Then as θ =...

I looked around the net and couldn't find an answer to this particular setup: Suppose I am at rest with two friends (friend A and friend B). We all have a clock. All three clocks are synchronized and tick at the same rate. Now one of my two friends (friend A) starts his rocket engine and leave...

Does the distinction between "local" versus "long distance" phone service still have any basis in the equipment used to implement the service? Are "local" calls actually transmitted only on the networks and equipment owned by the local phone company?

Why or why not?

Homework Statement Liquid ammonia is heated as it flows at a mean velocity of 2 m s–1 through a circular pipe. The pipe, which has an internal diameter of 75 mm, is at a uniform temperature of 27°C, and the ammonia at a section 1.2 m from the inlet to the pipe has a temperature of –23°C. Use...

Moving fluids are generally in a state of non-equilibrium. However, in fluid dynamics, people generally assume a state of local thermodynamic equilibrium and argue that in such a condition, equilibrium thermodynamic concepts such as pressure, temperature, entropy, internal energy etc. can be...

One way to talk about it precisely is in your program (great program btw). When running the program, you clearly demonstrate a difference in correlation when only "local" vs. "non-Local" variables are used. In order to help understand your program, I have modified some defaults on the program...

Hi. Bell formulated local realism as follows: The probability of a coincidence between separated measurements of particles with correlated (e.g. identical or opposite) orientation properties can be written as $$P(a,b)=\int{d\lambda\cdot \rho(\lambda)\cdot p_A(a,\lambda)\cdot...

Asked to find first three terms in the local behavior as x→0+of the solutions of y′+xy=1/x^3 This was taken by bender and orszag book Working : I tried to use method of dominance but later realized that we can find using the series expansion. But I am not sure how to proceed. Please advise...

Is there any interpretation of QM that is Psi-ontic, local, and has wave function collapse?

This is a simple question but i keep finding conflicting answers and don't understand scientific and mathamatical language well enough to consult reliable data.. 'Cause I'm a dunce. So, is EVERYTHING outside the local group leaving us, or are some things in the virgo supercluster contracting...

I have been reading in various sources that the directly measured value of Ho is high than the global value inferred by precise measurements of the CMB. The local value seems to be around 73 km/s/Mpc where as the global value inferred, assuming a flat Lamda CDM model is about 67 km/s/Mpc...

Hi. A while ago, I apparently had a wrong idea about the meaning of realism. I stood corrected: I'm still struggling with those subtleties. Would following formulation be more appropriate: "Realism means, that every observable ##x## is attributed a probability distribution ##p_P(x)## that...

The mantra in theoretical physics is that global gauge transformations are physical symmetries of a theory, whereas local gauge transformations are simply redundancies (representing redundant degrees of freedom (dof)) of a theory. My question is, what distinguishes them (other than being...

Homework Statement Let γ : I → Rn be a regular smooth curve. Show that the map γ is locally injective, that is for all t0 ∈ I there is some ε > 0 so that γ is injective when restricted to (t0 − ε , t0 + ε ) ∩ I. Homework Equations The Attempt at a Solution [/B] So I know a function (or a...

Can it be either?

I am a little unsure how to get started with a homework question. Essentially, I have to calculate the local heat flux at a distance 1.2m (x) along a pipe. I have the fluid's properties and have calculated the Reynolds number, for which I've determined the flow to be turbulent and therefore do...

http://onlinelibrary.wiley.com/doi/10.1002/lpor.201500252/abstract https://arxiv.org/pdf/1509.06217v2.pdf "...it has been implicitly assumed that this scheme is of inherently nonlocal nature, and therefore exclusive to quantum systems. Here, we experimentally demonstrate that the concept of...

Hello! Can someone explain to me what exactly a local gauge invariance is? I am reading my first particle physics book and it seems that putting this local gauge invariance to different lagrangians you obtain most of the standard model. The math makes sense to me, I just don't see what is the...