Is it ever explained why so many races evolve, technologically speaking, on a nearly parallel course in the Star Trek universe? Obviously their physical and social evolution was far from parallel but technologically nearly every space faring civilization evolved along nearly identical lines.    I know every race developed technologically at different rates, a few are thousands of years more advanced, but the similarities are undeniable. I also know that some races were gifted technology by other, more advanced civilizations and some stole tech to further the advancement of their own.  Is this just a subtle plot point within the Trek universe to avoid multiple technology theories? As such does it make it easier to say everyone above a specific technological checkpoint have similar tech?
The vast majority of intelligent species in the Star Trek universe are bipedal, humanoid creatures.  From the lot I've seen of TOS, TNG, DS9, Voyager, Enterprise, and the movies, it seems that this coincidence goes largely unquestioned.  Metaknowledge grants that it is much easier to have human actors portray human-like beings, and so this was probably done due to budgetary/technological limitations.  However, I'm wondering if an in-universe reason for this was ever given or explored?
What does goodness of fit mean in context of linear regression I am having trouble understanding the concept of 'goodness of fit' w.r.t linear regression. The name suggests that the goodness of fit test is used to determine how well a model fits the data.  But the linear model is already the 'best' fit since we have minimized the sum of the squared error terms. Why do we need to test 'goodness of fit' again? We know it is a good fit because we minimized the sum of the squared errors. Let's say you tell me to produce randomly a number from 1-100, and I choose the number 47. Can it be said that there is a specific reason I chose the number 47, and that it is not completely random? By random I mean that there is absolutely no reason this number in particular was chosen.    It seems odd to me, since it seems like since I have applied conscious effort to produce or choose a number within that range, or even without range, that it can't be truly random, but there might be a reason why I chose that number amongst the many others I could have chosen.  I guess the general question, which I'm interested to know if any philosophers in the past have discussed, is whether our thoughts are necessarily based on prior thoughts, or if thoughts can be truly spontaneous and random? If $a,b$ are positive integers such that $\gcd(a,b)=1$, then show that $\gcd(a+b, a-b)=1$ or $2$. and $\gcd(a^2+b^2, a^2-b^2)=1$ or $2 $ If  $a,b$ are positive integers such that $\gcd(a,b)=1$, then show that $\gcd(a+b, a-b)=1$ or $2$ and $\gcd(a^2+b^2, a^2-b^2)=1$ or $2 $. Progress We have   $\gcd(a,b)=1\implies \exists u,v\in \mathbb Z$ such that $au+bv=1\implies a^2u'+bv'=1, u',v'\in \mathbb Z$. Let $\gcd(a+b, a-b)=d$. Then $\mid (a+b)x+(a-b)y, \forall x,y\in \mathbb Z$. How to show $\gcd(a+b, a-b)=1$ or $2$ and $\gcd(a^2+b^2, a^2-b^2)=1$ or $2 $. Why I can't escape spaces on a bash script? I'm trying to escape the space char for a path in Bash, but neither using a  or  works.  .sh script:  ROOT="/home/hogar/Documents/files/" FILE=${ROOT}"bdd.encrypted" DESTINATION="/home/hogar/Ubuntu\ One/folder"  mv ${FILE} ${DESTINATION}   After execute the script (./file) this is the result:  mv: target 'One/folder' is not a directory   Why does the mv command split the string, and how do I stop this from happening? "going to come down" vs "going to have to come down" What is the difference between the following sentences?        This fence is going to come down.   This fence is going to have to come down.      I have doubt that when you are saying fence is going to have to come down, that is enough to say it right? but why I hear in movies saying fence is going to have to come down, is there a difference between them? How long should it take to refresh a Developer Sandbox? I refreshed a Developer Sandbox, and almost 24 hours it is still "pending". Is this normal? Are there any actions I can take to speed up the process? When I created the Sandbox it took barely more than 10 minutes to create.  Thanks, Adrian How would one go about proving that the rationals are not the countable intersection of open sets? I'm trying to prove that the rationals are not the countable intersection of open sets, but I still can't understand why   $$\bigcap_{n \in \mathbf{N}} \left\{\left(q - \frac 1n, q + \frac 1n\right) : q \in \mathbf{Q}\right\}$$   isn't a counter-example. Any ideas? Thanks! We have a job that is set to run Monday thru Friday. Up until two weeks ago, it ran fine 5 days a week. For the last two weeks it has failed on Monday. I am unable to locate where to find the point of failure.   ### Example Scripts 0 2 * * 1-5 /admin/scripts/example.exp 1&gt;/dev/null 2&gt;&amp;1   We run AIX 7.1.  I've looked in the /var/log/ and there is no cron file there. Looking for advice to add to this so we can troubleshoot.   I found that the log is located in /var/adm/log. Further we are getting this error repeatedly ever since this date/time. How do I clear this max limit?  c queue max run limit reached Fri Nov 25 21:52:00 2016 ! rescheduling a cron job Fri Nov 25 21:52:00 2016 Back-transformation of regression coefficients I'm doing a linear regression with a transformed dependent variable. The following transformation was done so that the assumption of normality of residuals would hold. The untransformed dependant variable was negatively skewed, and the following transform made it close to normal:   $$Y=\sqrt{50-Y_{orig}}$$  where $Y_{orig}$ is the dependent variable on the original scale.   I think it makes sense to use some transformation on the $\beta$ coefficients to work our way back to the original scale. Using the following regression equation,   $$Y=\sqrt{50-Y_{orig}}=\alpha+\beta \cdot X$$  and by fixing $X=0$, we have   $$\alpha=\sqrt{50-Y_{orig}}=\sqrt{50-\alpha_{orig}}$$  And finally,  $$\alpha_{orig}=50-\alpha^2$$  Using the same logic, I found  $$\beta_{orig}=\alpha\space(\alpha-2\beta)+\beta^2+\alpha_{orig}-50$$  Now things work very well for a model with 1 or 2 predictors; the back-transformed coefficients resemble the original ones, only now I can trust the standard errors. The problem comes when including an interaction term, such as  $$Y=\alpha+X_1\beta_{X_1}+X_2\beta_{X_2}+X_1X_2\beta_{X_1X_2}$$  Then the back-transformation for the $\beta$s are not so close to the ones from the original scale, and I'm not sure why that happens. I'm also unsure if the formula found for back-transforming a beta coefficient is usable as is for the 3rd $\beta$ (for the interaction term). Before going into crazy algebra, I thought I'd ask for advice... Showing a tensor is not a simple tensor How is Cycles different from Blender Internal? 16.04 Cannot install anything from Ubuntu Software center Whenever I double click a deb file, it'd be opened in software center. However, when I click "install" button, it'd change to "installing" for a second but then turn back to "install" and nothing happens. It also says "This software comes from a 3rd party and may contain non-free components" at the bottom. I have enabled all the options in Software &amp; Updates and also tried reinstalling software center but nothing helped. How can I "grep" patterns across multiple lines? It seems I am misusing grep/egrep.   I was trying to search for strings in multiple line and could not find a match while I know that what I'm looking for should match. Originally I thought that my regexes were wrong but I eventually read that these tools operate per line (also my regexes were so trivial it could not be the issue).  So which tool would one use to search patterns across multiple lines? How to prove that $d \sin(x)/dx = \cos(x)$ without circular logic such as L'Hôpital's rule? Which is the best visualization for contingency tables? Which is best plot, from statistical standpoint, to show a , which is typically being analyzed by chi-square test? Is it a dodged barplot, stacked barplot, heatmap, contour plot, jitterred scatterplot, multiple lines plot or something else? Should one show absolute values or percentages?  Edit: Or as @forecaster suggests in the comments, the table of numbers is itself a simple plot and should be sufficient. In a reverse split, what happens to odd lots? Let us say for example that I have 27 shares of stock X (there really is an X but its identity is not relevant).  In this example, X does a 5:1 reverse split. How many shares do I end up with. If I have fractional shares, what can I do with them? While adding to an Answer to  question, I needed to use the above phrase, and I suddenly realised I was unsure whether to write "is" or "are".   There is more than one way to skin a cat. If there are more than one species of cat, we will flay each species differently.   I don't think that second example above sounds quite right to me (disregarding the meaning - sorry!), but in my original Answer I felt "is" would have been even worse.  Is "are" always wrong here? If so, what exactly is the rationale? If not, is there a case where it's unquestionably preferred – and why is that?    Note that in both the problematic Answer and my example attempting to mimic the same context more briefly, the writer doesn't know how many there are. There may be one, more, or even none.  Getting even more specific, the writer might have an opinion on how many there might be, and wish to convey his leanings by choice of verb form if language allows this to be done succinctly. What are the badges I can earn on each site, and what are the exact criteria for earning each badge? I want to be able to close an alert box automatically using Javascript after a certain amount of time or on a specific event (i.e. onkeypress).  From my research, it doesn't look like that's possible with the built-in alert() function.  Is there a way to override it and have control over the dialog box that it opens?  Also, I don't want an override that shows a hidden div as the alert.  I need an actual dialog box. How to best respond to a request to send a passport scan by unsecured email? It is not uncommon for travel or holiday accommodation companies to ask for a scan of your passport by email. Sometimes local laws require them to keep a record of the passport numbers of all visitors. I'm happy to provide that information but you usually have to send it in an unsecured email, which may have consequences .  Could these companies be more responsible, and provide a public cryptographic key at least?  Are there other steps you should take to protect yourself, if you do send by unsecured email?