In Einstein's thought experiment (if I understand it correctly) a person in a sealed elevator in space accelerating at 9.807 m/s2 would not be able to tell the difference between that and the effect of gravity on Earth. Is there any sort of experiment the person in the elevator could do that would tell him he is feeling acceleration rather than gravity from Earth? For instance, I think that if you hung two weights from long strings some distance apart on Earth they would not be parallel. But in the elevator they would be.  Sorry if this has been asked before, but I couldn't find the answer on this forum.
So, according to Einstein's theory of general relativity, gravity is not a force instead it is a consequence of objects with mass deforming spacetime, right? And so, according to him, there is no difference between standing on a platform accelerating upwards at 9.81 m/s^2 and standing on Earth, right? But, there is a difference. At least, I think it's a valid difference. If you drop two apples from a high altitude on Earth, not only will they accelerate downwards at 9.81m/s^2 but they will also slightly move towards each other because the Earth is a sphere and gravity acts radially inwards pulling the two apples closer to each other. But if you drop the apples from the same height above the accelerating platform, the apples will only appear to accelerate downwards at 9.81 m/s^2 but will not move towards each other like they would on Earth. Why is this true? Is this even a valid difference? If it isn't, why isn't it?
So today I woke up and noticed new item in inventory which was a booster pack containing 3 cards from L4D 2. From what I see on market these booster packs are new (graph only shows up to 19 of June). No matter the game it seems to always contain 3 cards. There are two actions I can do with it: unpack or sell. There is fancy animation when you unpack the booster ;)    I'm not exactly sure why I got it, I have few guesses:   I got new badge, power player - this could give me a booster? Because of new badge I reached level 10 - maybe every couple levels there are gifts? It just dropped randomly for everyone?   Maybe together we could rule out above guesses. It's also interesting from the point of market, to estimate how many boosters are there. With some games they seem to be more valuable than 3 cards separately, but that maybe only initial confusion. Novel about a teleportation device and a con artist alien I read two (maybe three) books about a protagonist who communicates with an alien who provides the instructions on how to create a device to teleport. The device is flawed in that it purposefully uses more energy (much more) by taking it from the rotation of the Earth.  The main character and two others continue to fight, commit intrigue, etc. The alien then uses them to recruit other races to do the same thing. How to export data as CSV format from SQL Server using sqlcmd? how to pass value like 100,102,103 to view params I am trying to zoom plot numbers.Plot numbers like 1 10-12 13/P road 20(A) 100&amp;102 and etc.I am able to zoom to all combination plot numbers except 1,2,3.when I pass such value its trowing error:  1 feature types requested, but found 2 view params specified  geoserver sql view is:  select * from plotboundary where nmindar='%nmindar%' and plno='%plno%'   default values and validation are  Name  | Default Value   | validation  nmidar| Hanagawadi I A  | ^[\w\d\s]+$  plno  |  100,102&amp;103    | ^[ A-Za-z0-9_ *@.\/#&amp;+-\,()-_]*$   ajax function:   $.ajax({             url: 'http://XX.168.1.XX:8089/geoserver/XX/ows?service=WFS&amp;version=1.0.0&amp;request=GetFeature&amp;typeName=XX:vwplot&amp;maxFeatures=5000&amp;outputFormat=text/javascript',             contentType: 'application/json',             dataType: 'jsonp',             jsonpCallback: "parseResponse",             data: {                 viewparams: "nmindar:" + nmindar + ";plno:" + plno             }   Can any one tell me how to pass value to viewparams in geoserver, value includes comma. For example as mentioned above "100,102&amp;103" is a single value(plot number).Here   comma is not a separator. How to deal with variable income in the budget We have a budget planned out for various categories, and in order to make ends meet we count on child support for my wife's child from a previous marriage.  However, lately we have not been receiving this amount.  How do we deal with this in the budget?    My wife has just been "borrowing" it from our savings, but I don't think that is reasonable given that I find it highly unlikely we will ever be able to recover it.  On the other hand, she doesn't think it reasonable to cut out of her budget and cutting it out of the budget for the kids (which is where it really should be going!) isn't reasonable either. I want to find a set of integer solutions of Diophantine equation: $ax + by = c$, and apparently $\gcd(a,b)|c$. Then by what formula can I use to find $x$ and $y$ ?   I tried to play around with it: $x = (c - by)/a$, hence $a|(c - by)$.     $a$, $c$ and $b$ are known. So to obtain integer solution for $a$, then $c - by = ak$, and I lost from here, because $y = (c - ak)/b$. I kept repeating this routine and could not find a way to get rid of it? Any hint?  Thanks, Chan I have some music discs, but every time I put it in a jukebox I can't hear it. It says it's playing, my friend (on PS4) says he can hear it, but I don't. All other audio is fine, I can hear the game audio fine, even if I have a world that's only me: it still doesn't produce jukebox sounds. It visually shows that it's playing (the notes come out of the jukebox) but there is no music. I play on Pocket Edition. Can someone help me resolve this issue? Mysql: Select rows from a table that are not in another How to escape text for regular expression in Java Let $S$ and $W$ be subsets of a vector space $V$. Show that if $S$ is a subset of $W$, then $\mathrm{span}(S)$ is a subspace of $\mathrm{span}(W)$ Let $S$ and $W$ be subsets of a vector space $V$. Show that if $S$ is a subset of $W$, then $\mathrm{span}(S)$ is a subspace of $\mathrm{span}(W)$.  Ok I'm finally understanding what each of these things mean.. but I'm running out of ideas on how to actually show it without using arbitrary vector space examples like Rn. Since sets and subspaces are kind of new its hard to figure out how to write correct proofs with them.   I can see how if $V = \mathbb{R}^3$ and $S = \{(1,1,1)\}$ and $W = \{(1,1,1), (1,1,2)\}$ then $\mathrm{span}(S) = R1(line), span(W) = R2(plane)$ and that R1 is a subspace of R2... im just having trouble showing this officially when all vector spaces and sets are completely in general....  I could get as far as writing out $S=(u_1,u_2,\dots,u_n)$, $u_i \in V$ and same with $W$, but I can't really figure out what else to do in this sort of proof. FIELD_INTEGRITY_EXCEPTION: field integrity exception: unknown (invalid user or group: 005XXXXXXXXXXXX) I've a object called myobject__c. This object is private in OWD Setting.  Now when admin create a new record of this object then I want to share this record with a user(community user). For this I've written a code in trigger to create a sharing record of this object (myobject__Share).  But I am getting a problem of :-      FIELD_INTEGRITY_EXCEPTION: field integrity exception: unknown (invalid   user or group: 005XXXXXXXXXXXXX).   how can I solve this problem and second doubt is can we create share record for community user or not. Current  enables one to upgrade to macOS Mojave from a stable release, but I want to try out a fresh installation instead of upgrading with previous data, so that I can assess it better.  I've downloaded an application named "macOS Mojave Beta" from the App Store, and running it would presumably result in an upgrade. Now I wonder what to do next. Would  and booting from it be a good idea, when I'm working with a Beta version? I think my device got a malware. A lock screen with ads sometimes appear, and I must swipe an area at the bottom of the screen to open the phone. I am in Eastern Europe, some ads are in Slavic languages, and they are seemingly related to travel.    Image resized. Click to view the full image  I have seen ads for Lot Air (Polish carrier). I recently went to their site.  Considering my recent surfing activity and the nature of the ads, I guess the malware is connected to airlines active in Eastern Europe.  The lock screen also promotes the app "DU Quick Charger" by claiming it has recharged the phone extra fast during screen off. (!?) It also shows battery level. I have never installed DU Quick Charger. I doubt DU Quick Charger is installed on the phone.  The problem started after installing Ryanair app. The problem is maybe, but not surely, related to this. Uninstalling Ryanair and restarting the phone doesn't remove the occasional appearance of this lock screen. After a while the situation has changed for the worse, now this lock screen appears after EVERY screen off.  I have always used Avast. I am not rooted and only install via Google Play.  What is this? And how do I remove it? Annoying flickering in 16.04 LTS - Chrome I've upgraded from 4.4.0 to 4.4.8 and then 4.5.2 on Ubuntu 16.04 LTS 64-bit, and it's still happening.   At 4.5.2 it's even more frequent, and mainly in Chrome (haven't tried firefox or opera just yet). Every time I open a new web page. Any way to fix that, or is it a bug?  00:02.0 VGA compatible controller: Intel Corporation HD Graphics 5500 (rev 09) 04:00.0 Display controller: Advanced Micro Devices, Inc. [AMD/ATI] Venus XTX [Radeon HD 8890M / R9 M275X/M375X] (rev 81)   Cheers. Limit Ordinal Question how to prove this result.     $\alpha$ is limit ordinal if and only if $\beta&lt;\alpha$ implies $\beta+1&lt;\alpha$ for any $\beta$.   I am getting confused because of the definition of limit ordinal. it says     $\alpha=\sup\{\beta: \beta&lt;\alpha\}=\bigcup\alpha$    for sup I am ok but for $\alpha=\bigcup\alpha$ how ?? How do I set exposure with a manual flash? I recently got an old Canon AE-1 film camera back in working order. I'd like to use my modern 430EXII Speedlight flash with it, however since there is no TTL metering, I have no idea how much the flash will affect the exposure of my shot (note that I have confirmed that the AE-1 will trigger the flash). I'd rather not discover that my shots were either blown out or way to dark after going through several rolls of film.  Are there any basic rules-of-thumb or basic calculations for anticipating how much a burst from the 430EXII will affect the exposure of a subject at various distances? How to add a Login / Logout link in Main navigation menu? How can I add a Login link to the "Main navigation" menu?  When a user clicks on the link, it should take them to the /user/login page. Once they login, the link should change to say "Logout" instead of "Login".  Is there any way to add such a link? How far can I refactor the code in someone else's question? I am trying to animate in 2d. I do it with planes that have textures on them. I recently came up with the idea of having a plane with an image sequence of mouths because animating actual lip syncing by hand takes too long and isn't really necessary for what I'm trying to acomplish. However, when playing back the animation in textured viewport shading the animated texture stays at the last frame until the animation stops. I can use the arrow keys and it works fine as well as scrubbing through the timeline, just not when playing back the animation with alt+a. Can anyone help me with this problem? Migrate to *any* site? Wouldn't it be a good idea to be able to vote for questions to be moved to any Stack Exchange site? For example, I just voted  as off topic, but that was all I could do. I wish I could've voted it be moved to .  It's OK to have the predefined list of sites that is now when voting to move, but it would be nice to have a more link, where we could pick any Stack Exchange site.  Here's a quick mockup of how I see this implemented:    When the more link is clicked, a list of all the Stack Exchange sites should appear.