So I just finished off learning quantum mechanics and special relativity. I just realized that in general relativity, there is Einstein field equation which must be solved in order to talk about physical movements.   But I see several solutions. So is there a thing as a solution that describes our universe perfectly at astronomical scales/macroscopic level (not quantum level)?   Or do we have to solve the equation for different cases occurring in our reality?
-I'm not a religious person so this is not a denial. I'm just trying to understand the most fundamental topic about Universe.  -I know the Big Bang cosmological model is not a law but it's a theory.  -I'm a non-Native English speaker so please let me know if the question is not clear for you.  -This question came to my mind after watching
Does and has both are used with singular pronouns (He has the bottle , He does play cricket , etc) whereas Do and have are used with plural pronouns ( They have the bottle , Do they like cricket? , etc)  But still we use Does with have ( She does have a car ). Why? Shouldn't it be     She does has a car. Is it possible to have two background images?  For instance, I'd like to have one image repeat across the top (repeat-x), and another repeat across the entire page (repeat), where the one across the entire page is behind the one which repeats across the top.  I've found that I can achieve the desired effect for two background images by setting the background of html and body:  html {     background: url(images/bg.png); }  body {     background: url(images/bgtop.png) repeat-x; }   Is this "good" CSS?  Is there a better method?  And what if I wanted three or more background images? Ubuntu 18.10 Cosmic not starting GNOME session on bootup Map matrix element to string There are a lot of software in Windows to merge PDF files but how can we do the same in Ubuntu? Will yearly moderation statistics be published on all sites this year, and future years? How to use Stokes theorem in the presence of holes? I am using 64bit 2.10.1-Pisa on Windows 10.  When I set up my composer to print, everything looks fine until I try to print or export. The composer goes completely blank and outputs a corrupted PDF using the Export to PDF function. The PDF file won't even open.  I had the same result exporting to PNG.  When I try to use the PDF document printer instead of exporting, QGIS stops responding indefinitely. How do you hide back faces so that you only see faces when its normal is facing the camera? When exporting it for use in a game, the face is rendered in only the direction of its normal, so this would be useful to have something similar. HUD is not working after upgrade My HUD is not working after I upgraded from 11.04 (and or 11.10).  It prompts for command and it tries loading for 4 seconds then gives up. How are answers with the same vote score sorted? When a new question is asked how are the answers sorted?  I just answered a question and there were two other answers.  All three answers have 0 votes and no edits.  Immediately after I answered my answer appeared first.  Now the order refreshed,  it appears they are sorted by reputation. Search [tag1] OR [tag2] Is there a way to search questions that are tagged with either tag1 or tag2?  Actually, I would like the general filter,      ([tag1] AND [tag2], ...) OR ([tag3]   AND [tag4], ...) OR ...   And even     [tag1] AND ([tag2] OR [tag3])   I need that because I'm looking for interesting questions and I have to search for each tag separately. Most of the time when I mixed different nuts in a bowl, I observed that the big Brazil nuts were always on top while the small peanuts settled near the base. No matter how you take it, if the big nuts are put at the bottom and then the small nuts are poured, then also after some time the big ones will come to the top. Will not the gravity attract those big nuts more and eventually will they not remain at the base? But it doesn't happen!   I googled it and found the term Brazil-nut Effect but couldn't find any proper explanation. What is the physical explanation for this effect? show all my unanswered questions from SE Any way how to get    my all un-answered questions  from across all SE sites? How can I install Celestia on Ubuntu 18.04.1? Can a wizard use his familiar's senses to enlarge his "you can see" area? I'm a Sri Lankan passport holder. I'm planning to travel to China in January and have to transit in Malaysia. I wonder whether I can obtain a Malaysian transit visa in KLIA 2 when I'm flying back to Sri Lanka. What is the difference between "used space", "size" and "size on disk"? There is only one partition for both system files and personal data, which is C:. The other two partitions are for boot and for recovery.  Now I have two different reports on the size of C: on my Windows 7:   by clicking the property of C:, it shows 59.4 GB for "used space"; by selecting all contents (I have setup to view all hidden files and directories) under C: and viewing their property, it shows 46.9 GB for "size" and 47.6 GB for "size on disk".   Here are my questions:   I was wondering why the two reports are not the same, and where the difference comes? in the second way, why "size" and "size on disk" are different? What do they mean actually? What is the difference between them and "used space" in the first way?   Thanks in advance! Retrieve the position (X,Y) of an HTML element relative to the browser window I am debating whether or not to get the Potato Sack (yes, I realize I've been debating for several weeks now) bundle through steam.  I already own: Defense Grid: The Awakening, Super Meat Boy, and Audiosurf, all of which are part of the sack pack. What happens if I buy the Potato Sack?  Do I get 2nd copies of the three above mentioned games to gift elsewhere?  Is the price of the bundle reduced by the games I already have?  Do I get nothing special for already owning those 3 games?