If I have two "entangled" particles and I know the spin state of every one of them. Then, I change the spin state of one of the particles, will it affect the spin state of the other particle even if it is far away? Also, it turns out that entanglement is actually real and can be used for many things, is this just the result of a false interpretation and understanding of Quantum Mechanics by those who claim it or it can be really done? And if it is real, will it just change our interpretation of GR?
Bearing in mind I am a layman - with no background in physics - please could someone explain what the "big deal" is with quantum entanglement?  I used to think I understood it - that 2 particles, say a light-year apart spatially, could affect each other physically, instantly.  Here I would understand the "big deal".  On further reading I've come to understand (maybe incorrectly) that the spatially separated particles may not affect each other, but in knowing one's properties you can infer the other's.  If that it the case, I don't see what the big deal is... 2 things have some properties set in correlation to each other at the point of entanglement, they are separated, measured, and found to have these properties...?  What am I missing? Is it that the particles properties are in an "un-set" state, and only when measured do they get set?  (i.e. the wave-function collapses).  If this is true - why do we think this instead of the more intuitive thought that the properties were set at an earlier time?
For some reason I can't unhide my objects anymore in this file. Is it a bug? Can't install Oracle Java 8 in Ubuntu 16.04 I want to use the GameJolt API, how do I protect my private key which is in my game? GameJolt is a gaming platform/website that offers API access with features like achievements tracking for users, etc. I can use the API no problem on my tests but what I'm concerned about is the private key that is issued to my game. How do I ensure that it's protected from people that want to decompile my game? Once  they get the API private key, they will be able to do anything with it. Install a single specific package from future distribution I'm currently using precise. I need to upgrade a certain package (namely  and it's dependencies) to a newer version, which is currently found in raring (alfa at the time of writing this). How to do it ?  What will happen if I just add to my sources.list:  deb http://archive.ubuntu.com/ubuntu raring main   Will the next apt-get update / apt-get upgrade, upgrade most of my system to raring then ? How to hide notification center button in Mountain Lion? I am using Mountain Lion.  The only advantage (for me) over the gesture is that Option + clicking the button enables/disables showing alerts and banners (toggles the switch in the notifications center).  Is there a way to hide the button in the status bar that opens notification center? Why do only two sexes exist for animals? Cannot determine size of graphic Constructor not defined error in test code I want to write as a math fraction 1/4 " ( a quarter of inch). I want to write this fraction out of an equation because is a characteristic of an element. Cartoon with a young unicorn and a demon Background Video is shown in Rendered mode but not when szene is rendered How can I log into a different Google account? It only shows one of my Google accounts. I want to log into a different one but I don't want them connected in any way. What do I do? To be honest I find it hard to keep up with all the changes, and very frequently I have to go look at the privileges list to see whether a user (that I'm looking at, so I have his reputation value) has a certain privilege or not.  However, I still don't know what that user will actually see or how the site actually behaves for that user.  There's quite a number of posts here on meta about "where did this go" and "why can't I" and I can't really tell either way how a site behaves for a user with a reputation level of 2500.  So, I propose the following functionality:   For all users, be able to view the site as though you had less reputation than you actually have Bonus-feature: For all users, be able to use the site at that reputation level, unless some features of low-level users conflict with your actual functionality For mods, be able to view the site as a specific users (be able to see all he sees, exactly the way he sees it), but of course not pose as that user (ie. things I do would still be me)   The UI could be merged into the mod menu and the privileges menu:    (Note, I chose a user randomly, Olivier Pons is in no way related to this question or flags, or whatever that I know of.) I noticed that $f(x) = x\phi(x)$ seems to be one-to-one, where $\phi(x)$ is Euler's Phi function.  In particular, I'm writing some numerical python code and the line I have looks something like  sorted([n*phi(n) for n in range(1,1000)])   and there are no duplicates in the list.  First, is it one-to-one?  Second, if it is, is there a simple proof sketch? Why is the automatic login disabled for users with encrypted home? I've tried to setup an autologin, but that isn't possible, because my home is encrypted. What are the reasons for this?  PS. Here I have described my problem: . To make Latin-letter variables bold I can use e.g. \mathbf{a}, but while putting Greek letters or symbols such as \nabla inside \mathbf doesn't cause any errors or warnings, it also doesn't do anything else.  What is the best way to make bold math symbols, in particular Greek letters and \nabla? How can I replace a string in a file(s)? Replacing strings in files based on certain search criteria is a very common task. How can I    replace string foo with bar in all files in the current directory? do the same recursively for sub directories? replace only if the file name matches another string? replace only if the string is found in a certain context? replace if the string is on a certain line number? replace multiple strings with the same replacement replace multiple strings with different replacements I have a datetime column in MySQL.   How can I convert it to the display as mm/dd/yy H:M (AM/PM) using PHP? Is there any difference between “which” and “that”? I have been attempting this problem for a while, it is an assignment problem so I don't want somebody to just post the answer, I'm just looking for hints.  Let $\mathfrak{u}(n,\mathbb{C})$ be the Lie algebra of strictly upper triangular $n\times n$ matrices over $\mathbb{C}$.  I am trying to show that $\mathfrak{u}(n,\mathbb{C})$ is a nilpotent Lie algebra for $n\geq 2$.  This is what I have looked at so far.  I have done some explicit calculations (I shall omit the bulk of them and just summarise below) for $n=2,3,4$ and have come up with some ideas.  Let $L=\mathfrak{u}(n, \mathbb{C})$.  If $n=2$,  $L^1 = [L, L] = &lt;0&gt;_{\mathbb{C}}$  So $L$ is nilpotent.  If $n=3$,  $L^1 = [L, L] = &lt;e_{13}&gt;_{\mathbb{C}}$  $L^2 = [L, L^1] = &lt;0&gt;_{\mathbb{C}} = \left\{ 0 \right\}$  So, $L$ is nilpotent.  If $n=3$  $L^1 = [L,L] = &lt;e_{13},e_{14},e_{24}&gt;_\mathbb{C}$  $L^2 = [L,L^1] = &lt;e_{14}&gt;_{\mathbb{C}}$  $L^3 = [L, L^2] = &lt;0&gt;_{\mathbb{C}} = \left\{ 0 \right\}$  So, $L$ is nilpotent.  So my hypothesis so far is that for an arbitrary $m\in\mathbb{N}$, $L^{m-1}=\{0\}$  My instinct is to do this by induction. My base case, $n=2$ has already been shown. Now I assume that $\mathfrak{u}(n,\mathbb{C})$ is nilpotent for $n=k$ ($k\in\mathbb{N}$) and consider the case for n=k+1.  However, I have no idea how to link these two cases together. I have read in Introduction to Lie Algebras and Representation Theory - J.E. Humphreys that $L^k$ should be spanned by basis vectors $e_{ij}$ where $j-i=k+1$ - however in my calculations for $L^1$, I obtain an $e_{14}$ which does not satisfy 4-1=2.  Am I missing something completely obvious? Or have I made a mistake somewhere? (I have checked my calculations numerous times, but cannot find any errors!)  Thanks,  Andy.