Suppose we're in an unknown place in the universe, only knowing that the Milky Way is somewhere is the sky (but of course, younger that it actually is, due to unknown distance light has to travel to reach our position).  Under detailed observation, could we recognize our galaxy?  Our galaxy alone would probably look like just another younger spiral galaxy. But, its vicinity would also include younger Magellanic Clouds, Andromeda galaxy, etc. And maybe other properties that could hint that galaxy being ours.    Note: I severely edited the initial post to keep the core question, as comments and the proposed "duplicate question" kept focusing on the background, rather than the actual question. I know these kind of edits are discouraged as they can invalidate answers, but the only answer so far is not affected by the edit.
There is a possibility for our universe to be the surface volume of a (higher-dimensional) hyperspace. So if this possibility is true,then is there also a possibility that the other galaxies we see are our own galaxy after light has completed revolution around the three dimensional boundary (surface volume).  Know that we see different shapes for different galaxies.This can be perhaps due to other reasons like-   distance light travelled, the angle through which we look to see the other galaxy (possibly Milky Way) after     it made any number of revolutions, the part of the other galaxy (possibly Milky Way) which we see,and some other properties of light and space.   Only our Milky Way galaxy is just one possibility  Another possibilities are the number of galaxies are far less than we see because we see the same galaxy several times due to curved space.  Any possibilities for the above statements to be true?
Evaluate definite interval of normal distribution I know that an easy to handle formula for the CDF of a normal distribution is somewhat missing, due to the complicated error function in it.  However, I wonder if there is a a nice formula for $N(c_{-} \leq x &lt; c_{+}| \mu, \sigma^2)$. Or what the "state of the art" approximation for this problem might be. Screen resolution stuck at 1024x768 Why is everything floating in space so cold? Of course there is pretty hot stuff too. For example Suns.  But isn't the vacuum of space the perfect containment for heat? And shouldn't the rare collision with particles even heat up an object that floats around in space?  Why aren't they hot from time to time? Is it because they loose their heat by radiant heat?  And if so does radiant heat emission always occur until the object is the same temperature as the surrounding or does it depend on other factors? Why does the series $\sum_{n=1}^\infty\frac1n$ not converge? Can someone give a simple explanation as to why the       $$\sum_{n=1}^\infty\frac1n=\frac 1 1 + \frac 12 + \frac 13 + \cdots $$   doesn't converge, on the other hand it grows very slowly?   I'd prefer an easily comprehensible explanation rather than a rigorous proof regularly found in undergraduate textbooks. What harm can be done with a copy of one's passport? During Thor's interrogation, Agent Coulson exits the room and Loki enters and informs him that his father Odin had passed away and that he cannot undo his banishment. Not only does he communicate with Thor, but he goes to the area where Mjölnir is embedded in the rock and attempts to lift it, with SHIELD scientists and agents completely oblivious to his presence. Loki shows a similar ability when he converses with 'The Other' and when he manipulates Erik Selvig. Is this a part of Loki's illusion powers or another one of his abilities that has not been addressed? How was he able to visit Earth without using the Bifrost? Why are there $|G/G'|$ 1-dimensional representations of $G$? Let $G'$ be the derived subgroup of a finite group $G$.   We have a correspondence $\{\mathrm{reps \ of \ G/G'}\} \longleftrightarrow \{\mathrm{reps \ of \ G \ with \ kernel \ containing \ G' }\} $  If we restrict to 1-dimensional reps, we get:  $\{\mathrm{1\ dimensional \ reps \ of \ G/G'}\} \longleftrightarrow \{\mathrm{1 \ dimensional \ reps \ of \ G \ with \ kernel \ containing \ G' }\} $  Now my notes say that there are $|G/G'|$ 1-dimensional reps of $G$. Since there are $|G/G'|$ 1-dimensional reps of $G/G'$, this must mean that all 1-dimensional reps of $G$ have kernel containing $G'$. Why is this so?  Thanks Three files have suddenly appeared in my home directory, called "client_state.xml", "lockfile", and "time_stats_log". The last two are empty. I'm wondering how they got there. It's not the first time it has happened, but the last time was weeks ago; I deleted the files and nothing broke or complained. I haven't been able to think of what I was doing at the time reported by stat $filename. Is there any way I can find out where they came from?  Alternatively, is there a way to monitor the home directory (but not sub-directories) for the creation of files? What's the difference between the list methods append() and extend()? Fantasy/scifi combo - band of travelers who must get from "sphere" or domain to domain - each geographic area is ruled by a magician - it turns out later these are people who are unwittingly tapping into the computer grid they all live on to alter their own reality? How to read and write into file using JavaScript? Can anybody give some sample code to read and write a file using JavaScript? Proving the so-called "Well Ordering Principle" The achievements drop-down menu in the new top bar shows me when a question/answer earns me reputation and how much, and that's great, but I don't know what caused that to happen. I'd like to know why I received reputation: was it an upvote? An accepted answer? An accepted edit? If I have the list of reputation values in my head I can figure it out, but it would help me to see it somewhere in the drop-down, even as title text on hover.    Edit:  It sounds like the items in the menu can roll up multiple events, and that's why it doesn't show the event there. How about adding a link to my reputation tab to the menu so I can quickly get to a breakdown? Is there a nice solution to get a "presenter mode" for Latex presentations? I really like the way Keynote and MS Office (and also OpenOffice &amp; similar) support a presentation mode that displays the current slide, the next (and maybe previous) slide, the elapsed and current time, and also any notes attached to the slides on one screen and the presentation itself on the beamer/second screen.  It enables me to give good, professional presentations without having to know everything by heart (I suck at that).  I found a , but I am looking for alternatives, especially OS-independent would be great. Not having to create 3 different PDFs is a boon.  Any hints? Background notebook template with spiral How to sandbox applications? I want to run small untrusted programs, but restrict them from accessing any files outside of their folder, network access, and everything else that they don't really need. What is the simplest way to achieve this? When I vote up questions or answers, I'm not only increase poster's reputation but also saving a link to the post in my profile — the "Votes" tab shows all posts I have voted on, so it's possible to view the posts again without searching.  But finding the needed answer is uncomfortable when the number of posts voted on is too large.  Please add an option to search in my voted posts.  Adding a new  would be easier. But I think that a filter in the "Votes" tab will be more comfortable (at least for me). Also this filter could be used in other tabs in the profile, e.g. the "Answers" and "Questions" tabs. Change color of links created with \in, \at, etc Best way for a 'forgot password' implementation? Solve the second order ODE $(2x^2 + 1)y'' − 4xy' + 4y = 0$ I need help solving this past exam question, the professor posted exam questions with out solutions to last year's exam, I tried reduction of order, however that seemed to complicate things. And then I tried Euler-Cauchy method however I realized that won't work due to the $(2x^2 + 1)y''$.  Given $y_1=x$ is a solution $$(2x^2 + 1)y'' − 4xy' + 4y = 0$$ Find the second solution $y_2$ for equation.