Back in the '80s I read a short story (which might have been old, then) about aliens in a war with other aliens finding Earth which had previously been locked away, I think, by some kind of lock on the Moon.  After some misgivings, they unlocked Earth and landed to ask for help.  Earth seemed completely pastoral and they almost gave up hope of getting help, but persisted and humans finally agreed to help them.  At the end of the story, they get back in their space ship and wait for Earth's space ships to fly out and help them when the Earth itself grows an engine and flies after them.  I have been looking for this story on and off for a couple of decades and have never found it, but my daughter was asking about some of the short stories I enjoyed as a youngster and this one came up, so I'd really like to find it, now.  I've looked through several hundred old anthologies and haven't found it, yet, but I found StackExchange, so I'm hoping someone here can help me.  I know this isn't much detail to work with, but I'm working from old memories.  Thanks in advance for the help (or attempt).
First we are told that the Galactic Empire/Federation/Powers-that-be have kept the Earth locked up for being too warlike, but now their help is needed against invaders from another galaxy.  When the aliens land the first thing they meet is a talking bunny.      at the end when humans have accepted to join the fight the alien offers to send ships to transport them. The human leader tells that there is no need...  and the Earth accelerates away.   I must have read this sometime in the mid eighties, so no later than 84 or 85, but the story may be from the sixties or before.
Why don't metals bond when touched together? It is my understanding that metals are a crystal lattice of ions, held together by delocalized electrons, which move freely through the lattice (and conduct electricity, heat, etc.).   If two pieces of the same metal are touched together, why don't they bond?   It seems to me the delocalized electrons would move from one metal to the other, and extend the bond, holding the two pieces together. If the electrons don't move freely from one piece to the other, why would this not happen when a current is applied (through the two pieces)? I can't review posts anymore—was the minimum reputation changed? Is it just for me, or has the privilege to review new posts and late answers changed for everyone?  I recently started being more active in reviewing, but the rep requirement just shot up and I can not review anymore? The rep requirement has shot up to 500. Is this just for me, as a 'process", or has it been changed site wide? What happens to the holes in the skull where teeth were developing? In Skeptics.SE, a question regarding the skulls of children arose. Depicting a scary skull where the permenent teeth are "hidden" inside the jaws and the milk teeth are in the their place.  After all milk teeth fall out, and the permanent teeth "rise", do the holes left by them filled up, or do we go around with holes in our jaws?    The picture: How to escape braces (curly brackets) in a format string in .NET Minor "you have already raised this type of flag" bug? I flagged something as spam, then was only 90% sure I'd done so, so I clicked the flag link again to check. It showed me this:    I had, of course, only raised the spam flag, not the offensive/abusive/hate flag, so the latter probably shouldn't be saying I did.    Ah, this may be a duplicate, I didn't search enough:        And if so, it's been around a while. How to Fix Broken Packages? How do I fix broken packages when it is not working? When I try to fix broken packages, it tells me to "fix broken packages." What does the tilde at the end of a file name stand for? In Windows, I believe that files with a tilde in the file name represent files that are currently open in an application. For example, Microsoft Word creates a file with almost the same name as the file you currently have open, but with a tilde in the name. It's icon is also partially faded. As far as I'm aware, this signifies a temporary file that exists   in case the application crashes and you didn't get a chance to save your file, or to allow the original file to remain unlocked by the file system and accessible to other applications.   In Linux, I ran into a *.log file with a tilde at the end of the file name (scan.log~). Does that mean the log file is currently open in another application that is potentially writing to it? Force refresh view in LWC In Aura, we can do      $A.get('e.force:refreshView').fire();   to cause standard components to update.  How can we do an equivalent in LWC because sfdx refuses to publish .js code with $A in it saying the usage is disallowed in LWC?  For now i tricked it with   eval("$A.get('e.force:refreshView').fire();");   but that is obviously less than ideal.... Schengen visa application rejected because my US visa stamp expires in December. What are my options? I went to the Italian consulate in Washington, DC today and they would not accept my visa application because they said my US visa stamp cannot expire less than 3 months after the end of my trip to Italy. Here's my relevant visa and trip info:   US visa stamp expires on 16 Dec 2015 I-797 valid until 3 Mar 2017 Trip to Italy is from 15 Oct to 25 Oct 2015   Is it true that my visa stamp needs to be valid for 3 months after my trip, even though I can legally stay in the US until 2017? Does anyone have any suggestions for getting a Schengen visa in my situation? Let $\Omega=\mathbb{N}$. For each $E\subset\Omega$ let $N_n(E)$ be the cardinality of the set $E\cap \{1,2,\ldots,n\}$. Define $C=\left\{E: \lim_{n\rightarrow \infty} \frac{N_n(E)}{n} \text{ exists}\right\}$. Show that $C$ isn't a field.  I already know that it isn't closed to finite union of non-disjoint set but I can't see why. I saw a post that somebody said &quot;the set of natural numbers whose first digit is 1 doesn't have this limit&quot;. I'm in trouble to see why this limit wouldn't exists in finite unions. Thanks in advance. Schrödinger Equation for Two Electrons? I'm having trouble finding a simple answer to this question (maybe because there isn't one), but I'm just confused about how the Schrödinger Equation would look for two electrons. I understand that it would exist in 6 dimensional configuration space, but how does the potential look? It's confusing that the potential would be different for each electron depending on where the other one is. Story ID: Boy who is stuck at 5 years old with robot nanny Here's what I remember:  The boy is 5 years old, and has been for some time, because there's a bit in which he recalls turning 5 (celebrating his 5th birthday) many different times  There's a robot nanny in the apartment with him that he learned to disable so that he can hang out with the girl, who he isn't supposed to know. (In my mind the nanny bears somewhat of a resemblance to Muthr from the Wondla series... however I definitely read this story well before reading Wondla)  There's a neighbor girl who teaches him to read (I think she's like 9), and when they first meet she asks how old he is (5 is the last age at which growth/development can be successfully (and safely?) suspended) and he lies, saying that he's 6, but doesn't know why he does.  When a child whose aging process has been stopped learns how to read, they begin aging normally again, so the parents don't want them to learn to read.  The children who have stopped aging are kept apart from other children who grow normally-- they have separate playgrounds and the like  The injection/serum used to halt the aging process was developed by a scientist, who when he first shared his findings had a 5 year old son and injected him, then told the onlookers/potential buyers/other parents to come back in 20(?) years. When they did, their children were adults and no longer needed them or were ungrateful layabouts, and the scientist's son was still 5 years old, cute, needy, etc.  The main character has a discussion about how he wants to turn 6 with his parents and they agree but only because he's already learned to read and it's irreversible.  It's kinda dark and emphasizes the need that parents have to feel wanted. Please help! I remember it so vividly and I'd love to read it again! Determining the dimension of span$\{AB-BA : A,B \in M_{n \times n}(\mathbb R) \}$ Let $S$ be the subspace , of  $M_{n \times n}(\mathbb R)$ (the vector space of all $n \times n$ real matrices ) , generated by matrices of the form $AB-BA$ , where $A,B \in M_{n \times n}(\mathbb R)$ , then how do we prove that $\dim S=n^2-1$ ? The only thing that I can determine is that the trace of all matrices of $S$ is $0$ . Please help I have two Date values. I need to find number of weeks between them. I want to do it Apex Class. Not looking for formula fields.  So far I tried:  Integer numberofweeks = (projectStartDate - opp.Project_Start_Date__c)/7;    I receive this error:     Date arithmetic expressions must use Integer or Long arguments Programming with Dynamic Calculating conditional entropy given two random variables I have been reading a bit about conditional entropy, joint entropy, etc but I found this: $H(X|Y,Z)$ which seems to imply the entropy associated to $X$ given $Y$ and $Z$ (although I'm not sure how to describe it). Is it the amount of uncertainty of $X$  given that I know $Y$ and $Z$? Anyway, I'd like to know how to calculate it. I thought this expression means the following:  $$H(X|Y,Z) = -\sum p(x,y,z)log_{2}p(x|y,z)$$  and assuming that $p(x|y,z)$ means $\displaystyle \frac{p(x,y,z)}{p(y)p(z)}$, then  \begin{align} p(x|y,z)&amp;=\displaystyle \frac{p(x,y,z)}{p(x,y)p(z)}\frac{p(x,y)}{p(y)}\\&amp;=\displaystyle \frac{p(x,y,z)}{p(x,y)p(z)}p(x|y) \\&amp;=\displaystyle \frac{p(x,y,z)}{p(x,y)p(x,z)}\frac{p(x,z)}{p(z)}p(x|y)\\&amp;=\displaystyle \frac{p(x,y,z)}{p(x,y)p(x,z)}p(x|z)p(x|y) \end{align} but that doesn't really help.  Basically I wanted to get a nice identity such as $H(X|Y)=H(X,Y)-H(Y)$ for the case of two random variables.  Any help?  Thanks The system of equations Let $a,b,c\in \mathbb{R}$ that $a^{2}+b^{2}+c^{2}=1$. We want to find $x,y,z,w$ in the following equations:  $$\begin{align} x^{2}+y^{2}+z^{2}+w^{2}&amp;=1 \tag{1}\\ x^{2}+y^{2}-z^{2}-w^{2}&amp;=a \tag{2}\\ xw+yz&amp;=2b \tag{3}\\ yw-xz&amp;=2c.\tag{4} \end{align}$$ Enable 'on the fly' CRS transformation in QGIS 3? Is there a constructive way to exhibit a basis for $\mathbb{R}^\mathbb{N}$? How do I get money back for my foreign coins? Tonight I just cleaned my room and while doing this I found some money. I counted it and I found out that there are a lot of coins from 25 different countries.  I know that normally banks don't exchange foreign currencies in coins, but is there a way so that I can still get some money for my foreign coins?