Story where a man evades capture from a spaceship by walking round an asteroid
Collection of short stories; in one a spy attempts to escape detection on Mars's moon by moving faster than the spaceship can scan
Expected value of the number of flips until the first head Suppose we flip a coin until we see a head. What is the expected value of the number of flips we will take?  I am pretty new to expected value, so I tried to evaluate it by multiplying the probability of each scenario with the number of flips it took to get there (like taking the arithmetic mean). This didn't work though, because of the infinite possibilities. I'm really confused, and if someone were to provide an answer, I would really appreciate it if they could go into detail. Reason for the discreteness arising in quantum mechanics? What is the most essential reason that actually leads to the quantization. I am reading the book on quantum mechanics by Griffiths. The quanta in the infinite potential well for e.g. arise due to the boundary conditions, and the quanta in harmonic oscillator arise due to the commutation relations of the ladder operators, which give energy eigenvalues differing by a multiple of $\hbar$. But what actually is the reason for the discreteness in quantum theory? Which postulate is responsible for that. I tried going backwards, but for me it somehow seems to come magically out of the mathematics. Ubuntu 19.10 change desktop environment mongodb group values by multiple fields Why doesn't my command work when aliased? I use ps -ef | grep catalina | grep -v grep to print the tomcat process running on the system:  kshitiz   7099     1  0 May11 ?        00:02:29 /usr/lib/jvm/jdk1.8.0/bin/java -agentlib:jdwp=transport=dt_socket,suspend=y,address=localhost:38156 -Dcatalina.base=/home/kshitiz/Documents/workspaces/ggts/.metadata/.plugins/org.eclipse.wst.server.core/tmp1 -Dcatalina.home=/opt/tomcat-7.0.42 -Dwtp.deploy=/home/kshitiz/Documents/workspaces/ggts/.metadata/.plugins/org.eclipse.wst.server.core/tmp1/wtpwebapps -Djava.endorsed.dirs=/opt/tomcat-7.0.42/endorsed -Dfile.encoding=UTF-8 -classpath /opt/tomcat-7.0.42/bin/bootstrap.jar:/opt/tomcat-7.0.42/bin/tomcat-juli.jar:/usr/lib/jvm/jdk1.8.0/lib/tools.jar org.apache.catalina.startup.Bootstrap start   Then I use ps -ef | grep catalina | grep -v grep | awk -F' ' '{print $2}' to extract the process id:  7099   But when I alias the whole command alias tomcat_id="ps -ef | grep catalina | grep -v grep | awk -F' ' '{print $2}'" and use it via alias, it prints the whole text and awk doesn't seem to work.  type tomcat_id gives:  tomcat_id is aliased to `ps -ef | grep catalina | grep -v grep | awk -F' ' '{print }'' Bold italic vectors I am trying to display vectors as bold and italic. The command \mathbf sets the letters non-italic. I also googled a bit and stumbled upon \mathbf{\em y} or \mathbfit{y}, which all didn't work.  I hope someone can help me on this. Generic constraints, where T : struct and where T : class I am currently using 19.04 and I got "No new release found for 19.10" How come unpolarized light does not undergo destructive interference? As far as I know, unpolarized light is defined as light which has no clear axis of polarization, but electric field vectors in all directions. However, I also know that electric fields can be superpositioned. So this leads me to the conclusion that if unpolarized light has equal $\vec E$ vectors in all directions, they should cancel.   Obviously, though, this is wrong (we've got light!). What's the explanation? From : In calculus and other branches of mathematical analysis, an indeterminate form is an algebraic expression obtained in the context of limits. Limits involving algebraic operations are often performed by replacing subexpressions by their limits; if the expression obtained after this substitution does not give enough information to determine the original limit, it is known as an indeterminate form.    The indeterminate forms include $0^{0},\frac{0}{0},(\infty - \infty),1^{\infty}, \ \text{etc}\cdots$   My question is can anyone give me a nice explanation of why $1^{\infty}$ is considered to be an indeterminate form? Because, i don't see any justification of this fact. I am still perplexed. How to import a .max model into Blender? I've tried to import but I don't see the (.max) file as an option when importing. Is there another way to import the 3DMax model into Blender for rigging and animation? numbers of pages don't appear on pdf printed Event handler not working on dynamic content How do I change my timezone to UTC/GMT? Currently when I execute the date command from bash I get the following displayed  Thu May 17 12:21:00 IST 2012  Below is my timezone config based on executing dpkg-reconfigure tzdata     Current default time zone: 'Europe/Dublin'   Local time is now: Thu May 17 12:32:52 IST 2012.   Universal Time is now: Thu May 17 11:32:52 UTC 2012.     Any idea how I change from IST to UTC/GMT? How is the optimal probability cut-off in a ROC defined by the R package Epi? The plot below was created by R package Epi::ROC for a binary classification problem. There is an optimal cut off or threshold for the classification probability at which sensitivity and 1-specifitiy are balanced in some optimal way (called ps3 in the plot). My question is how this point is defined mathematically in this case and if there are other ways to define it. Check to see if an email is already in the database using prepared statements Suppose that $n \ge 2$. How to prove that the set $\mathcal D \subset M_n(\mathbb R)$ of the diagonalizable real matrices is not dense in $M_n(\mathbb R)$? Show that there are exactly 16 pairs of integers $(x,y)$ such that $11x+8y+17=xy$. Which year does Spider-Man: Homecoming take place in? The first scene of the movie is presumably set in the immediate aftermath of The Avengers. The movie then fast-forwards to '8 years later'.  But Spider-Man already appeared in Civil War as a high school student, which he still is in this movie. So what's the timeline here? If Avengers was set in 2012 and Civil War in 2016, how can Homecoming be in 2020?  Or am I wrong in assuming the canonical timelines of the other movies? When I shoot a ball vertically upward, its velocity is decreasing since  there is a downward acceleration of about $9.8\,\mathrm{ms}^{-2}$.   I have read that at the top most point, when $v = 0$, the acceleration is still $9.8\,\mathrm{ms}^{-2}$ in the downward direction where $v=0$. That is, the acceleration is still the same.  But at the highest point, the ball is stationary, so it is not even moving. How can it accelerate?