How to create new folder?
How can I safely create a nested directory in Python?
Isn't the uncertainty principle just non-fundamental limitations in our current technology that could be removed in a more advanced civilization? From what I understand, the  states that there is a fundamental natural limit to how accurately we can measure velocity and momentum at the same time. It's not a limit on equipment but just a natural phenomenon.  However, isn't this just an observational limit? There is a definite velocity and momentum, we just don't know it. As in, we can only know so much about the universe, but the universe still has definite characteristics.  Considering this, how do a wide range of quantum mechanical phenomena work? For example, quantum tunneling - its based on the fact that the position of the object is indefinite. But the position is definite, we just don't know it definitely. Or the famous light slot experiment? The creation of more light slots due to uncertainty of the photon's positions?  What I am basically asking is why is a limit on the observer, affecting the phenomenon he is observing? Isn't that equivalent to saying  because we haven't seen Star X, it doesn't exist? It's limiting the definition of the universe to the limits of our observation! Proving Pascal's Rule : ${{n} \choose {r}}={{n-1} \choose {r-1}}+{{n-1} \choose r}$ when $1\leq r\leq n$ I'm trying to prove that ${n \choose r}$ is equal to ${{n-1} \choose {r-1}}+{{n-1} \choose r}$ when $1\leq r\leq n$.  I suppose I could use the counting rules in probability, perhaps combination= ${{n} \choose {r}}=\frac{n!}{r!(n-r!)}$.  I want to see an actual proof behind this equation.  Does anyone have any ideas? What is the simplest way to prove the Earth is round? Assume you've come in contact with a tribe of people cut off from the rest of the world, or you've gone back in time several thousand years, or (more likely) you've got a numbskull cousin.  How would you prove that the Earth is, in fact, round? How can I compute the distance between two coordinates in TikZ? Given two points (defined, for instance using nodes), I want to compute the distance between them.   Is there some build in functionality in tikz to do this? If not, how can it be done using the mathematical engine?   The application I have in mind is to draw an circular arc centered at (a) and passing through some second point (b), where only (a) and (b) are known. How can I render an edge only mesh as solid lines? I have a schematic of a raspberry pi that is completely flat, no solid faces, just connected vertices.  Is it possible to render these lines somehow, so that it looks like a 2D drawing?  Maybe with freestyle? It is me who am to blame.    It is I who am to blame.      Which one is correct here? I am bewildered about these two sentences. Is there a page listing all fields? Can I rename the wp-admin folder? Is it possible to rename the wp-admin folder?  I know I could just rename it, but unless it's supported by the code lots of things would break.  If I use a custom folder name, it will make it slightly more secure, security by obscurity and all that. I've heard that exposing database IDs (in URLs, for example) is a security risk, but I'm having trouble understanding why.  Any opinions or links on why it's a risk, or why it isn't?  EDIT: of course the access is scoped, e.g. if you can't see resource foo?id=123 you'll get an error page. Otherwise the URL itself should be secret.  EDIT: if the URL is secret, it will probably contain a generated token that has a limited lifetime, e.g. valid for 1 hour and can only be used once.  EDIT (months later): my current preferred practice for this is to use UUIDS for IDs and expose them. If I'm using sequential numbers (usually for performance on some DBs) as IDs I like generating a UUID token for each entry as an alternate key, and expose that. If $G$ is a group and $G'$ is generated by $\{xyx^{-1}y^{-1}|x,y\in G\}$, then $G'\trianglelefteq G$ and  $G/G'$ is Abelian.  At first, I thought this is easy because I thought $g[x,y]g^{-1}=[gxg^{-1},gyg^{-1}]$. But it was a mistake. I could not prove that it is also subgroup of G and $G/G'$ is abelian. I need help. Probability of $p(x_1<x_2<\max(x_3,x_4))$ I have 13.04 installed from a DVD that I got on eBay but the application launcher is missing. I've tried CCSM but it won't work! What are the odd of a single coin toss after many consecutive ones? I have little knowledge of probability and have recently been thinking of a math problem I am sure you guys could answer  If for example I tossed a coin ten times and got all heads, would the odds of the next coin toss beeing heads be 50 50 or s very low as the odds of getting 11 in a row is tiny?   Thanks Why don't wizards always use multiple wands? C# 4.0 optional out/ref arguments TSA broke a lock for which they have a master key. How can I claim compensation? What is the origin of BrEng ‘bird’ meaning “young woman”? Bird:         (Brit.) a girl or young woman, esp one's girlfriend ()      According to  bird:         "maiden, young girl," c.1300, confused with   (q.v.), but felt by later writers as a figurative use of  (n.1). Modern slang meaning "young woman" is from 1915, and probably arose independently of the older word.      also :         , bird was used for ‘girl’, but this was probably owing to confusion with another similar middle English word, burde, which also meant ‘young woman’. The usage crops up from time to time in later centuries, clearly as an independent metaphorical application, but there does not really seem to be an unbroken chain of occurrences leading up to the sudden explosion in the use of bird for ‘young woman’ in the 20th century.   (www.dictionarycentral.com)      Modern usage of bird meaning girl appears to be unrelated to the old Middle Ages meaning. Etymonline dates it back precisely to 1915.    What is the modern origin of bird meaning young woman?  In what context did they start to use it at the beginning of the 20th century? Completion handlers and return values I'm looking into a restful design and would like to use the HTTP methods (POST, GET, ...) and HTTP headers as much as possible. I already found out that the HTTP methods PUT and DELETE are not supported from the browser.  Now I'm looking to get different representations of the same resource and would like to do this by changing the Accept header of the request. Depending on this Accept header, the server can serve a different view on the same resource.  Problem is that I didn't find a way to tell my browser to change this header.   The &lt;a..&gt; tag has a , that can have a mime type, looked like a good candidate but the header was still the browser default (in Firefox it can be changed in about:config with the network.http.accept.default key). Cannot determine size of graphic I'm trying to include graphics in my Latex-file, which I compiled with latex+dvipdf on OS X. Latex however returns this error: "Cannot determine size of graphic"  My graphic is exported from PowerPoint, so I have tried both .pdf and .png. I get the same errors for both.  Sample code that doesn't work:  \begin{figure}[htb] \begin{center} \leavevmode \includegraphics[width=0.8\textwidth]{graph.png} \end{center} \end{figure}   If I have to manually set some measurements of the image, please tell me how I can find out those measurements. I need the image to take up about 80% of text width and be centered. Thanks.