Why cannot we add gravity in quantum mechanics without additional dimensions as done in bosonic or superstring theory?
A list of inconveniences between quantum mechanics and (general) relativity?
Import a python module without the .py extension (Pardon if this seems a bit beginner, this is my first post in math - trying to improve my knowledge while tackling Project Euler problems)  I'm aware of Sigma notation, but is there a function/name for e.g.  $$ 4 + 3 + 2 + 1 \longrightarrow 10 ,$$  similar to $$4! = 4 \cdot 3 \cdot 2 \cdot 1 ,$$ which uses multiplication?   Edit: I found what I was looking for, but is there a name for this type of summation? if recursively find ext, then, else on unix This is what I normally use. But I need to recursively find an extension with, then, and else. The problem with this one is that it is not recursive.  if ls $HOME/Downloads/*.ext &gt;/dev/null 2&gt;&amp;1 then     : else     : fi Upload files upto 2GB from Apex I sold an investment in a standard brokerage account at a small loss because I needed the money for a down payment.  I still think it is a good investment, can I buy the same investment in a standard IRA without running into wash sale problems?  I will probably just wait the 30 days any way to avoid any headaches, but I want to know if there is a definitive answer on this.    Being as the cost basis in the traditional IRA doesn't matter, I wouldn't think there would be a problem. shopt works in command line, not found when run in a script I'm writing a script to copy some files around, and trying to use shopt -s dotglob  like .jshint and whatnot.    I can run shopt -s dotglob directly at a bash prompt with no error.  However, running the script throws the error:  script.sh: 81: script.sh: shopt: not found   I'm running this script in bash shell, with the shebang header #!/usr/bin/env bash.  Error line:  shopt -s dotglob cp -r $TEMP/img/* $TARGET/img/ cp -r $TEMP/js/* $TARGET/js/ cp -r $TEMP/less/* $TARGET/less/   Not finding anything helpful on google, any idea what the problem is here? I'm currently the proud owner of Frost the horse. What I want to know is, what will happen to him if I ride another horse?  Obviously nothing will happen as long as I have him in sight, e.g. I'll be able to ride Frost to make him my horse again.  Scenarios  But what will happen if, before I get back on Frost, I fast travel somewhere? Will he return to where I originally stole him, will he disappear forever, or can I own two horses simultaneously?  Ownership?  If he goes back to where I originally stole him, will I have to steal him again, and therefore never be his true owner again?  Two Horses?  The reason I'm asking is because I want to get Shadowmere (the Dark Brotherhood horse) while keeping Frost. Is it possible to do this, or will riding Shadowmere make me lose Frost forever? How do lexical closures work? While I was investigating a problem I had with lexical closures in Javascript code, I came along this problem in Python:  flist = []  for i in xrange(3):     def func(x): return x * i     flist.append(func)  for f in flist:     print f(2)   Note that this example mindfully avoids lambda. It prints "4 4 4", which is surprising. I'd expect "0 2 4".   This equivalent Perl code does it right:  my @flist = ();  foreach my $i (0 .. 2) {     push(@flist, sub {$i * $_[0]}); }  foreach my $f (@flist) {     print $f-&gt;(2), "\n"; }   "0 2 4" is printed.  Can you please explain the difference ?    Update:   The problem is not with i being global. This displays the same behavior:  flist = []  def outer():     for i in xrange(3):         def inner(x): return x * i         flist.append(inner)  outer() #~ print i   # commented because it causes an error  for f in flist:     print f(2)   As the commented line shows, i is unknown at that point. Still, it prints "4 4 4". A friend of mine has some very old photos where the deterioration process seems to have increased in the past few years, and the owner is worried about the preservation of these old memories.  They have been stored inside an album within plastic sleeves. The owner is not aware of the display method prior to that.   I have been informed by the owner that since being in their possession, they seem to be looking worse than when first viewed and seem to be falling apart.   He is looking for the best way to preserve these photos inside an album, but not really sure what would be the best method. I have suggested for the albums as a whole to be stored in vacuum sealed bags for now, but I'm not even sure if that is good!  I am looking for any suggestions or personal experiences from anyone who has had to deal with such photos and what they did to preserve their memories. Intersection of kernels and linear dependence of functionals Is $\mathbb{Z}[x]/(x^2+1)$ isomorphic to $\mathbb{Z}[i]$? How to collapse consecutive numbers into ranges? Density function for RV The density function for a random variable X is given in terms of a constant $c$.  Find the value of $c$.  What is the corresponding distribution function?  Sketch both the density and the distribution functions. Finally, find the probabilities.  5.1 $f(x)=0$ for $x&lt;0$ and $f(x)=\frac{c}{(x+1)^4}$ for $0&gt;x$   $P(X&gt;4)$  $P(X&lt;2)$  $P(1\le\ X&lt;3)$   I get $c=3$ by taking the integral, and then I am a little confused as to why  $F(x)=1-\frac{1}{(x+1)^3}$  Is that because in solving for $c$, I ended up with $1=\frac{c}{3(x+1)^3}$, so substituting c in I get $1=\frac{1}{(x+1)^3}$?  And, then  $P(X&gt;4)=1-P(X\le\ 4)$ $=1-(1-{1}{(1+4)^3})$ $=1/125$  $P(X&lt;2)=1-{1}{(1+2)^3}$ $=26/27$  I guess I am a little confused about what $F(x)$ and $f(x)$ actually MEAN? And thus that leads to my confusion about what the differences between $&gt;$ and $&lt;$ and greater than or equal to are, etc etc in terms of the equations. The ones above I solved by comparing to the book but I still don't understand what they mean really.  So as a result, I don't really get how to solve $P(1\le\ X&lt;3)$.  5.2 $f(x)=ce^x$ for $x&lt;0$ and $f(x)=ce^{-x}$ for $0&gt;x$  5.3 $f(x)=0$ for $x&lt;-1$ or $x&gt;2$ and $f(x)=cx^2$ for $-1&lt;x&lt;2$ Is there a way to recover deleted data from a SSD / USB Flash drive?  All I could find were recovery for damaged drives, but I want to recover deleted data.  So how do I do this? Transvection matrices generate $ \operatorname{SL}_n(\mathbb{R}) $ If the earth would stop spinning, what would happen? When may adjectives precede determiners? (E.g. too difficult a task) The expression too difficult a task sounds a little pompous, but it doesn't sound ungrammatical. According to my folk-beliefs about English grammar, determiners precede adjectives. However, the expression too difficult a task seems to controvert that belief.  Additionally, the expression too difficult of a task seems grammatical too.    Under what conditions may determiners precede adjectives? Are there conditions under which too difficult of a task would be a more grammatical expression than too difficult a task would be?   (This question does not ask what the question “How big of a problem” vs. “how big a problem” asks. That question does not pertain to determiners.) MATLAB superclass can not be found on the MATLAB's search path How can I improve Ubuntu overall system performance? Installing a strong-tie post anchor on unlevel concrete