From a traveler's point of view, as he is accelerating with $1g$, in under one year he would reach the speed of light. Note that from his point of view, everything looks normal so he could keep accelerating, except of course other than all distances become zero and time looks frozen, and probably eventually points ahead of him would become his behind, and time started moving backward. So, what prevents him from reaching speed faster than light?
When a spaceship is experiencing a constant acceleration of $10m/s^2$, the astronauts will be moving at nearly the speed of light after about a year in the earth's reference frame. This means the spaceship's energy will start to diverge as a function of the speed $v$ so there will be a huge amount of energy necessary to increase the speed of the ship any further. This way, the speed of light can never be crossed.  All of this is clear to me, but all of this is also formulated in earth's reference frame. But from the astronaut's reference frame: the spaceship is simply accelerating at $10m/s^2$ and so the force on the spaceship is constant. Then why would we need huge amounts of energy to accelerate the spaceship?  For example, I read somewhere that the amount of energy that would be needed to accelerate a large spaceship to half the speed of light is more than 2000 times the current world annual energy consumption. How does this make sense in the astronaut's (non-inertial) frame?
Unable to cover get set in apex test class How to make Biber also print the debug information in the log file? I've switched from BibTeX to Biber and I was struggling with some errors.  During those problems (see  and  ) I noticed that other users seem to get a more detailed output in the log file (see e. g. ).  I also tried to run biber --tool --debug myreferences.bib, but I'm still missing those details (like the problematic source text for a FATAL error)  example of my current project  command: biber -tool --debug references.bib   INFO - This is Biber 1.9 running in TOOL mode INFO - Config file is '/Users/mbg4/.biber.conf' INFO - Logfile is 'references.bib.blg' INFO - DEBUG mode: all messages are logged to 'references.bib.blg' INFO - Looking for bibtex format file 'references.bib' INFO - Decoding LaTeX character macros into UTF-8 INFO - Found BibTeX data source 'references.bib' WARN - Datamodel: Entry '2005' (references.bib): Invalid format '2005/12//' of date field 'date' - ignoring WARN - Datamodel: Entry '2002a' (references.bib): Invalid format '2002/12//' of date field 'date' - ignoring WARN - Datamodel: Entry 'Ferri2009' (references.bib): Invalid format '2009/3/25/' of date field 'date' - ignoring WARN - Datamodel: Entry 'Klein2005' (references.bib): Invalid format '2005/9//' of date field 'date' - ignoring WARN - Range field 'pages' in entry 'Prochazaka1983' is malformed, skipping WARN - Datamodel: Entry '2006b' (references.bib): Invalid format '2006/2//' of date field 'date' - ignoring WARN - Datamodel: Entry 'Lu2001a' (references.bib): Invalid format '2001/6/15/' of date field 'date' - ignoring WARN - Datamodel: Entry 'Schubert2002' (references.bib): Invalid format '2002/9//' of date field 'date' - ignoring WARN - Datamodel: Entry 'N.N.c' (references.bib): Invalid format 'Apr\,2003' of date field 'urldate' - ignoring FATAL - Caught signal: SEGV Likely your .bib has a very bad entry which causes libbtparse to crash:    how I'd like it to look like (the FATAL - Caught signal: SEGV line):  [496] bibtex.pm:1029&gt; DEBUG - Parsing namestring 'Coyle, ,Thomas W.' [496] bibtex.pm:94&gt; FATAL - Caught signal: SEGV   Used software   TeXLive 2014 on MacOS X  biblatex v2.9a biber 1.9 Boolean expression (grammar) parser in c++ I want to get random decimal digits out of a 6-faced die.  Let's say the die is fair, with an equal probability for each outcome. (But feel free to share any consequences of that not being true, if you feel like it.)  I will represent the outcome of a die roll as a base-6 number:   In base-6 there are only 6 possible digits: $\{0,1,2,3,4,5\}$. The die has faces numbered 1 to 6. Face $f$ corresponds to digit $f-1$.   Thus, I can represent as many die rolls as I like with a base-6 number:   If the die is rolled once:   Let's say the die stopped on face $5$. The final base-6 number will be $4$.  If the die is rolled twice:   Let's say the die stopped on face $5$. And then on face $3$. The final base-6 number will be $42$.  If I roll the dice 10 times:   Let's say the die stopped sequentially on faces $5$, $3$, $4$, $6$, $2$, $3$, $3$, $3$, $2$, and $4$. The final base-6 number will be $4235122213$.    Since I want decimal digits, I need to convert to base-10.   Base-6: $4235122213$ Base-10: $44753985$   For any given number of die rolls, how many different combinations exist? If there are $r$ die rolls, the total of possible combinations is $6^r$.   $r$ rolls — $6^r$ different combinations. $0$ rolls — only $1$ combination. $1$ roll — $6$ different combinations. $2$ rolls — $36$ different combinations. $3$ rolls — $216$ different combinations. $4$ rolls — $1296$ different combinations. $5$ rolls — $7776$ different combinations. $6$ rolls — $46656$ different combinations. $7$ rolls — $279936$ different combinations. $8$ rolls — $1679616$ different combinations. $9$ rolls — $10077696$ different combinations.   $n_r$ ($\in \mathbb{N_0}$) is the number obtained after $r$ die rolls through the process described previously: "If the die is rolled once, twice, ..."  It is impossible for $n_r$ to reach the number of possible different combinations ($6^r$). It will be always short by least $1$:  $$ 0 \leqslant n_r &lt; 6^r $$   $r$ rolls — $n_r$ never surpasses $6^r-1$. $0$ rolls — $n_r$ never surpasses $0$. $1$ roll — $n_r$ never surpasses $5$. $2$ rolls — $n_r$ never surpasses $35$. $3$ rolls — $n_r$ never surpasses $215$. $4$ rolls — $n_r$ never surpasses $1295$. $5$ rolls — $n_r$ never surpasses $7775$. $6$ rolls — $n_r$ never surpasses $46655$. $7$ rolls — $n_r$ never surpasses $279935$. $8$ rolls — $n_r$ never surpasses $1679615$. $9$ rolls — $n_r$ never surpasses $10077695$.   I can never trust the leftmost nor the rightmost digit (fringe digits), since the possible values are potentially restricted.   For $0$ rolls, the outcome is always $0$. For $1$ roll, the fringe digit never surpasses $5$. For $2$ rolls, the leftmost digit never surpasses $3$, and the rightmost, $5$. For $3$ rolls, the leftmost digit never surpasses $2$, and the rightmost, $5$. For $4$ rolls, the leftmost digit never surpasses $1$, and the rightmost, $5$. For $5$ rolls, the leftmost digit never surpasses $7$, and the rightmost, $5$. For $6$ rolls, the leftmost digit never surpasses $4$, and the rightmost, $5$. For $7$ rolls, the leftmost digit never surpasses $2$, and the rightmost, $5$. For $8$ rolls, the leftmost digit never surpasses $1$, and the rightmost, $5$. For $9$ rolls, the leftmost digit never surpasses $1$, and the rightmost, $5$.   The other digits seem perfectly random to me though. Am I wrong? In Inno Setup is it possible to add conditional statements to what in the [Run] section gets executed? Alternatively is it possible to manually update the built in progress bar? Basically I have 2 MSIs included and using Inno Setup as a bootstrapper, and depending on user input one or both of the MSIs are to be installed.  I have something working using Exec statements in CurStepChanged but it doesn't update the progress bar as the files are extracted and it looks like the installer is stalled.  I guess the end result is I want some progress bar updates while the files are extracted to the temp folder.  The following is my current code:  procedure CurStepChanged(CurStep: TSetupStep); var     ResultCode: Integer; begin     if(CurStep = ssInstall) then begin         if(InstallServer) then begin             ExtractTemporaryFile('ServerSetup.msi');             Exec('msiexec',ExpandConstant('/i "{tmp}\ServerSetup.msi" /qb INSTALLDIR="{code:GetInstallPath}\Server\" ALLUSERS=2'),'', SW_SHOW, ewWaitUntilTerminated, ResultCode);         end;         if(InstallClient) then begin             ExtractTemporaryFile('ClientSetup.msi');             Exec('msiexec',ExpandConstant('/i "{tmp}\ClientSetup.msi" /qb INSTALLDIR="{code:GetInstallPath}\Client\" ALLUSERS=2'),'', SW_SHOW, ewWaitUntilTerminated, ResultCode);         end;     end; end; Removing internal geometry So in the image below there are two circles, how can I remove the internal vertices between them without messing up the outside shape. I'm working on a gun and this is just a simple way to illustrate the issue I'm dealing with. If I where to go in and delete the internal faces it would leave holes on the outside of the object, is there a fast way to get around this? Meaning of Simplify's tolerance parameter The standard parameters of Douglas-Peucker's simplify algorithm are geometry and tolerance (e.g  in PostGIS). What's the meaning of the tolerance parameter? I know that the bigger the value, the coarser the geometry will be. But does the number has any unit or it is just arbitrary? How do I use one shape to delete a portion of another shape? I have created an arrow shape (rightmost in image), from which I wish to cut out the majority so that only two thin sides remain. The most accurate way to do this would be to duplicate the shape and to somehow use the duplicate (leftmost in image) to remove the chunk that I no longer desire from the original. I am not sure what to do after the duplication, however, or if this method is even possible? Is there a better one? Control cannot fall through from one case label How to use a proxy on the command line? I can set my proxy username and password along with proxy settings in the proxy ui but these settings do not work on the command line. How can I use apps such as wget &amp; ping on the command line with a proxy?  Example Details:   username: 1234 pass: linux proxy: proxy port: 8080 Why does Newton's Third Law actually work? My father explained to me how rockets work and he told me that Newton's Third Law of motion worked here. I asked him why it works and he didn't answer. I have wasted over a week thinking about this problem and now I am giving up. Can anyone explain why Newton's Third Law works? For reference, Newton's third law:  To every action there is always opposed an equal reaction: or the mutual actions of two bodies upon each other are always equal, and directed to contrary parts. What are the origins of the word "nice"? "The ones" or "those"? I recently corrected  &quot;ghettos, such as the ones found...&quot; to &quot;ghettos, such as those found...&quot;  Was I correct, or are both versions right? Alt-Tab shows two application switchers on Unity I started to have problems with my Ubuntu application switcher (Alt +  Tab) this morning. When I press Alt +  Tab, not only one, but two application switchers show up. Last night I customized some stuff using the Unity Tweak Tool. I thought I didn't touch the application switcher. So now it looks like this: The temperature and pressure everywhere inside the Sun reach the critical point to start nuclear reactions - there is no reason for it to take such a long time to complete the reaction process.  Just like a nuclear bomb will complete all the reaction within $10^{-6}$seconds.  Why does most of the hydrogen of the Sun still not react even though it reaches the critical point, and why take stars billions of years to run out of fuel? What's a good phrase for "refining a process which is hopelessly broken"? I'm looking for a turn of phrase to describe a situation where the powers that be wish to continue making small improvements to a process which, due to deep-rooted flaws, will never be close to accurate.  I'm working on a process for estimating the states of business objects, and there's interest in fixing some edge cases which have been noticed.  This could be worthwhile, but because of missing data we're already making heroic guesses.  So if implemented, we might get from 80.0 to 80.1% accuracy.  If we were at 99.5%, I'd be happy to get it to 99.6%, but in the current situation it doesn't seem productive.  We have some CS people on E.SE; what would you call it when someone wants to optimize a two-second process to load data, though once loaded it will be chewed on by an inefficient algorithm for hours?  Something like "bailing the ocean" or "fixing a leaky faucet in a burning building" is close to what I have in mind.  There's also "rearranging deck chairs on the Titanic," but that carries an implication that the changes are wholly useless, and that events are coming to a head. How to determine if string contains specific substring within the first X characters I want to check whether Value1 below contains "abc" within the first X characters. How would you check this with an if statement?  var Value1 = "ddabcgghh";  if (Value1.Contains("abc")) {     found = true; }   It could be within the first 3, 4 or 5 characters. I find it funny that Java (or the java.util library) does not have a built-in function to calculate difference in dates. I want to subtract one date from another to get the elapsed time between them. What is the best way to do this?   I know the simple way is to take the difference of the time in milliseconds and then convert that into days. However, I wanted to know if this works in all cases (with daylight saving, etc.). Error term in equally spaced nodes Getting a stack overflow exception when declaring a large array The following code is generating a stack overflow error for me  int main(int argc, char* argv[]) {     int sieve[2000000];     return 0; }   How do I get around this? I am using Turbo C++ but would like to keep my code in C  EDIT:  Thanks for the advice.  The code above was only for example, I actually declare the array in a function and not in sub main.  Also, I needed the array to be initialized to zeros, so when I googled malloc, I discovered that calloc was perfect for my purposes.  Malloc/calloc also has the advantage over allocating on the stack of allowing me to declare the size using a variable.