The sun is a continuous explosion. The reason we cannot hear the sun is because of the vacuum separating us.  If that space was to be filled with air, would the sun be audible?
Theoretically if I were able to build some sort of device that let me sit 1 foot away from the surface of the Sun (or any star for that matter) without being vaporized, would a star produce any sort of audible sound at that distance?   From my understanding, sound waves need a medium to propagate through (air, water, etc).   Does this mean that all stars are completely silent (in the audible spectrum of frequencies at least) as they fuse  hydrogen into helium?   I know stars emit radio, xray, infrared, ultraviolet electromagnetic waves, but how about audible (20 Hz to 20Khz) frequencies?   For some reason it seems like this process would produce some sort of sound.
How can I make a bluish "white" LED less blue? Allow setuid on shell scripts The setuid permission bit tells Linux to run a program with the effective user id of the owner instead of the executor:  &gt; cat setuid-test.c  #include &lt;stdio.h&gt; #include &lt;unistd.h&gt;  int main(int argc, char** argv) {     printf("%d", geteuid());     return 0; }  &gt; gcc -o setuid-test setuid-test.c &gt; ./setuid-test  1000  &gt; sudo chown nobody ./setuid-test; sudo chmod +s ./setuid-test &gt; ./setuid-test  65534   However, this only applies to executables; shell scripts ignore the setuid bit:  &gt; cat setuid-test2  #!/bin/bash id -u  &gt; ./setuid-test2  1000  &gt; sudo chown nobody ./setuid-test2; sudo chmod +s ./setuid-test2 &gt; ./setuid-test2  1000     Wikipedia :     Due to the increased likelihood of security flaws, many operating systems ignore the setuid attribute when applied to executable shell scripts.   Assuming I'm willing to accept those risks, is there any way to tell Linux to treat the setuid bit the same on shell scripts as it does on executables?  If not, is there a common workaround for this problem? My current solution is to add a sudoers entry to allow ALL to run a given script as the user I want it run as, with NOPASSWD to avoid the password prompt. The main downsides to that is the need for a sudoers entry every time I want to do this, and the need for the caller to sudo some-script instead of just some-script I want something similar to "preview" in macs.  For example: I want an image editor that ONLY does simple adjustments like increase/decrease contrast, saturation, exposure, color tinting.... rotate, flip vertically, flip horizontally, make black and white, change size or format, crop.  THATS IT.  I know gimp can do all those things but its a bit overkill.  I just want to right click an image, open it with this magical program i just described, do a few quick adjustments, and then save and exit.  Nothing really fancy.  Anyone know of anything like this?  Btw I am using ubuntu 12.04 :) It rocks and I am glad I switched from mac, i just need to replace this one piece of software. What do we mean by hyperparameters? $X$ and $Y$ are independent $U(0,1)$ random variables.   I have to find $E[X|X&gt;Y]$.   I found it out by integrating $\int_0^1 \int_y^1 x dxdy$ to get $\frac{1}{3}$ as the answer but this is wrong according to the answer key. What is the mistake that I have made? How can I download an APK file from the Play Store? What are the common phrases, words, abbreviations that are used on Stack Overflow, Server Fault, Super User, Meta Stack Overflow, and the other Stack Exchange sites? This is meant to be a very quick overview, not an in-depth tutorial. When considering whether a term ought to be included, please use this test:  New user comes in and posts on day 1. What terminology or jargon are they likely to run into (comments, support, system messages, etc.) that cannot be understood from the context without prior experience with the site (that is, clear only if known). For example: &quot;This is a dupe. Flag a diamond mod to close or migrate to SU.&quot; Huh? Can these instruction be made clear from the glossary? Is it clear for those for whom English is a second language?  Please:  Edit the existing answer Insert relevant links to more detailed information on the term/phrase/abbreviation Add only factual information Keep it very, very brief, terse, and to the point Delete your own comments once they become irrelevant (integrated into the glossary) Use the Edit Summary box to note reasons for your edit, not comments  Please avoid:  Opinion Using abbreviations, terms, and phrases inside a description Unverified information Uncommon terms, abbreviations, phrases Long descriptions Unnecessary detail - link to the relevant FAQ instead Citations or examples of usage Inside jokes that are not common on all of the trilogy () Common Internet jargon (that is, , , , etc.) unless usage here differs significantly  Recurring discussion: While the experiment to keep meta-discussion in the comments is going well (that is, deleting them once consensus is reached) it is clear that some discussions will be recurring, and we'll have to keep a record around so people new to the glossary can understand the consensus already reached. Add a new answer if you believe a new issue is likely to come up repeatedly. For instance, discussion about what terms to include, whether the glossary should be broken up to make linking easier, or formatting issues might be best discussed in new answer/comment posts. I'm looking for a book that starts with the premise that (once the population size had exceeded a certain number) the future development of mankind (revolutions and wars in so and so many years, colonization of other planets in so and so many years, and so on) could be predicted completely by applied statistics. (IIRC, they used slide rules for those exact predictions, but that is certainly owed to the time the story was written). Next, the predictability was used to take a few tiny measures that would change mankind's fate in a favourable way. After a long time, the predictive system fails(?) because a mutation occurs in some person(s).  And now is the part where I'm not sure if it belongs to this or another story: The mutation results in the ability to "beam" by thinking of a place where one has been before... Solve the following system of equations  $ \begin{cases}  x_1^{'}(t)=x_1(t)+3x_2(t) \\  x_2^{'}(t)=3x_1(t)-2x_2(t)-x_3(t) \\  x_3^{'}=-x_2(t)+x_3(t)\end{cases} $.  First, I create the column vectors $X$ and $X^{'}$. Then the matrix $$A= \begin{bmatrix} 1 &amp; 3 &amp; 0  \\ 3 &amp; -2 &amp; -1 \\ 0 &amp; -1 &amp; 1  \\ \end{bmatrix} $$  Now, I find the eigenvalues, $-4,3,1$ and their corresponding eigenvectors $(-3,5,1)^T (-3,-2,1)^T (1,0,3)^T$.   I'm just not sure how to take it from here and solve the system of differential equations. I want a diagonal matrix $D$ so that I can read the solutions easy, but I'm not sure how to do it.  EDIT   Building on @Francisco 's answer, I'd have that:  $$X=c_1  (-3,5,1)^T  e^{-4t}   + c_2 (-3,-2,1)^T e^{3t} + c_3 (1,0,3)^T e^{t} $$.  But I believe this could be written in a simpler form. I am currently using Sheep It! to render my blend (built on v2.68c) on multiple computers, and I noticed something rather strange. According to the log on-site, the frames rendered from other people's blends were completing in 3 to 4 minutes. This was on an 4 core i5. My main rig (with an 8 core i7) was completing frames in no less than half an hour. How is this possible?  To clarify, these people's frames are very complex, often with very detailed textures. I have 2 objects in my blend. Below are the options I changed for my blend:   Aspect Ratio: 1000px x 1000px Output: PNG Clamp Indirect: 0.98 Render Sampling: 128 Min Light Bounces: 0 Max Light Bounces: 4 Cycles Render   Is there something in there that I should change to make it go faster? I can't really comprehend how it's going to quickly.  EDIT: To answer what @Duarte asked...   System Specs: i7-920, 3GB DDR3, GT 630, Windows 10 I have two circles, extended to form a sort of coin with a star on it. It is not complex at all. I have Firefox and Steam running in the background, but not actively. I've been away from the computer for 8 hours and noticed this behavior. (I am running Blender from Steam.) I made sure when I began rendering that the blend was set for CPU rendering.          And to answer what @pycoder asked, yes, I am using Cycles Render. Math book: Exercise - Solution environment If I use this code provided by a question formulate of Sebastian .  \documentclass{article} \usepackage[most]{tcolorbox} \usepackage{lipsum}  \newtcolorbox[auto counter]{problem}[2][]{% breakable, blankest, enhanced, attach boxed title to top left={yshift=-\tcboxedtitleheight}, left=\tcboxedtitlewidth+1mm, top=0pt, colback=white, fonttitle=\bfseries\sffamily, coltitle={cyan!60!black}, colbacktitle=white, colframe=white, title=\thetcbcounter,  overlay unbroken and first={% \node[fill=gray!30, inner sep=1pt, minimum width=\tcboxedtitlewidth,  outer sep=0pt, text=cyan!60!black, anchor=north] at(title.south)  {\foreach \i in {1,...,#2}{\if#2gt1{\,}\fi$\bullet$}};},#1}  \begin{document}  \lipsum[1]  \begin{problem}{1} \lipsum[2] \end{problem}  \begin{problem}{4} \lipsum[3] \end{problem}  \begin{problem}{2} \lipsum[4] \end{problem}  \end{document}   How could we create solutions environment, so we have at the end of the book solution of the exercises where each one have reference to chapter, page, number of exercise with the corresponding level of difficulty? What word describes random unfitting accusations I really dont know how to describe this. Im having a discussion with someone, I was sharing information that I found on a topic. Randomly im called out as being rude when nowhere was there evidence of rudeness exchanged. This person seems to have a history of claiming people have a problem or are being rude out of the random blue.   Is there a word to describe these random accusations that dont connect to anything? I realised, reading another Phys.SE question about  that I don't really understand how  works. Particularly concerning, for a SCUBA diver.  The top answers to that question seem to claim that balloons get their "sense of down" from a pressure differential. They continue: when a car accelerates, the air at the back of the car becomes more dense, and at the front less dense, changing the plane of the pressure differential and so also, the balloon's sense of up. I find that extremely hard to credit. However, I realised that I don't really know why less dense things float in more dense things.  I'm fairly sure it's something to do with displacement of heavier things by lighter things, and I think pressure acting on the lighter thing's surface has something to do with it, but that's about it. How to avoid messages from applications which I ran with a &? I ran dolphin like this:  dolphin . &amp;   I see messages in the console like these:  QPixmap::scaled: Pixmap is a null pixmap   How can I keep the console clean or silent? Hero who is against enhancements but has some himself Why can't we downvote our own posts? Once in a blue moon, I've wanted the ability to downvote my own answer to some question.  ()  Obviously upvoting one's own posts is out of the question.  But down is different.  Voting my own answer down can help me improve the site by pushing my answer lower in the ranking than another answer with a better or more situation-appropriate alternative.  It's not something I'd do often, but I would use this feature if it were available.  If implemented, I'd expect this feature to operate just like downvotes on other user's posts.  That is:   I get a few seconds to undo the downvote;  I get to remove the downvote after an edit to the post;  I lose a point for placing the downvote (CW excepted); I lose two points for receiving the downvote (CW excepted).   If you're noticing that I'd lose 3 points for downvoting my own non-CW post, congratulations! You can add!  I can think of a couple of potential downsides to this change.  The first one may be a dealbreaker; the second is probably not that big a deal.   Strategic downvoting of oneself: since you can undo the vote after an edit, and you can always edit your own posts, someone could downvote themselves soon after posting (especially on a FGITW answer) to garner extra sympathy upvotes. Badge collecting: the Peer Pressure badge just got easier, because if you have a -2 score on an answer, just downvote and delete for an instant badge. In Ubuntu ISO MBR, why does a GPT partition overlap the boot partition, and make MBR uneditable? Disable sleep on laptop lid close in tty1 I'm using Ubuntu Desktop 15.10 on a laptop and it runs an Apache server with SSH as well. When using a GUI, I have the power options set to not sleep at all even when the laptop lid is closed, but recently I stopped the X-System and am now using TTY1 instead to save resources. However, in TTY1, if I close the laptop lid, the computer goes to sleep and prevents the SSH and Apache server from working. Any way to prevent this easily? The realistic answer I bet is to use Ubuntu Server instead (unless I'm mistaken and Ubuntu Server will also sleep on lid close) but I don't exactly want to switch yet unless there's an easy way to switch to it like you can switch from ubuntu-desktop to lubuntu-desktop? Any advice is welcome to prevent the computer from sleeping I frequently prefer to look for questions on superuser .    I have never been able to determine how these search results are ordered.  Typically, search results are returned in order of relevance and the search help says they are "weighted heavily towards question title matches", but in this case, you would think that the search would order them based on whatever tab is currently selected (newest, hot, active)?  I ordinarily never stray outside of 'newest', but it's clear the results are not sorted by age. Should an off-topic question always be downvoted? The upvote tooltip says:      This question shows research effort; it is useful and clear.   The downvote tooltip says:      This question does not show any research effort; it is unclear or not useful.   Sometimes, a question can show research effort, be useful, be clear, but just not in the good place. Voting to close the question and downvoting seems like a double penalty.  Should an off-topic question always be downvoted ?