Theory of relativity paradox? I have seen the classical twin paradox before. It uses a twin stationary on Earth and the other traveling away and back. I have seen many contradictory solutions for it, some use general relativity, others use special relativity, either way, I have never been satisfied with what I've read. They always try to break the symmetry through the traveling twin's acceleration and deceleration, but never quite succeed.  So, let's do away with the classical twin paradox and let's explain a much simpler, perfectly symmetrical version of it where both twins are moving towards each other.  So imagine we have Twin A in a spaceship, and Twin B in another. They are both traveling at the same speed towards each other.  If I understand relativity properly:   From Twin A's frame of reference, he's stationary and Twin B is moving at a constant speed towards him, therefore, Twin B is aging slower. From Twin B's frame of reference, he's stationary and Twin A is moving at a constant speed towards him, therefore, Twin A is aging slower.   When they both finally meet, they both think that the other is younger. Which one of them is right?
How is the classical twin paradox resolved? I read a lot about the classical twin paradox recently. What confuses me is that some authors claim that it can be resolved within , others say that you need . Now, what is true (and why)?
Why won't my follower, Serana, follow me? I told my follower (Serana) to wait. But this is different. I told her to go somewhere and wait so it will activate the enemies. Well it did and I killed them. But Serana seems to be not following me anymore. I can't tell her to follow me. And she is constantly in a squatting position. The only thing I can do is tell her to wait somewhere else to move her. And I can't part ways because I'm doing a main quest and she has to be there. Can anybody give me a tip on what to do? How do I study the "correlation" between a continuous variable and a categorical variable? Most modern texts spend some time deriving the  that connects S matrix elements to time ordered field correlation functions. It seems essential, and really helps clear up what you are calculating. Yet some earlier texts and even some modern texts (e.g.  by R. Klauber) seem to skip right past this, working everything out in the "interaction" picture. It seems there must be something going wrong with this latter procedure, but I am not quite able to put it together. Calculate the last digit of $3^{347}$ I think i know how to solve it but is that the best way? Is there a better way (using number theory). What i do is: knowing that  1st power last digit: 3 2nd power last digit: 9 3rd power last digit: 7 4rh power last digit: 1 5th power last digit: 3    $3^{347} = 3^{5\cdot69+2} = (3^5)^{69} \cdot3^2 = 3\cdot3^2=3^3=27 $ so the result is $7$. Why can't I import "pygtk" with Python 3.2 from PyDev? Search only for the currently active language Does the concept of infinity have any practical applications? I know what you're thinking: "of course it has, for example, it can be used to tell you how many times you can go around a circle". But that isn't really true, now is it? You'd be dead or the world would go under long before an infinite amount of loops had been reached.  Are there any practical applications for the concept of infinity? Is it a useful concept in maths at all?  I know that Donald E. Knuth has argued that for all practical purposes, a very, very large number has the same effect as infinity, in his book "Things a Computer Scientist Rarely Talks About" (can't remember the exact quote, nor find it online, unfortunately).  Examples are appreciated. The latest kernel is causing problems with my sound, which worked fine with an older version. As I have only Ubuntu installed, Grub is not getting displayed while booting. How can I manually choose my kernel version while booting? How should I calculate $\lim_{n\rightarrow \infty} \frac{1^n+2^n+3^n+...+n^n}{n^n}$ How should I calculate the below limit  $$\lim_{n\rightarrow \infty} \frac{1^n+2^n+3^n+...+n^n}{n^n}$$ I have no idea where to start from. `--no-install-recommends` only specified packages I want to install xfce4-goodies but I don't want Midori Browser. With --no-install-recommends I don't know how to specify only Midori. I want the rest of packages. How to do that? Thanks! In a tic-tac-toe implementation I guess that the challenging part is to determine the best move to be played by the machine.  What are the algorithms that can pursued? I'm looking into implementations from simple to complex. How would I go about tackling this part of the problem? At what point is the ~/.bashrc file created? How can I use Gmail (in Chrome) as the default email handler in Windows 8?  I used to use GmailNotifier in Windows 7, but that doesn't seem to work anymore. Clicking on a mailto: link simply opens Chrome with a blank page.  I am not interested in using the Mail app built into Windows 8. Problem with Refsection I can't seem to get the reference within my {refsection}.  \documentclass[a4paper]{article}  \newcommand{\myparagraph}[1]{\paragraph{#1}\mbox{}\\}  \usepackage[     backend=bibtex,     isbn=false,     url=false,     doi=false,     eprint=false, ]{biblatex}  %Point to the bibliography db \addbibresource{mybib.bib}  \begin{document}  \include{myparagraph}  \end{document}   My paragraph file  \myparagraph{\fullcite{dante1320}} \begin{refsection}  \cite{manzoni1827}  \printbibliography[heading=subbibliography] \end{refsection}   I get the first citation (dante1320) right, but the second prints as [manzoni1827]. I don't get any error when I run Bibtex concerning the missing reference. But I got it when I run Latex: LaTeX Warning: Citation 'manzoni1827' on page 2 undefined on input line 5. Isomorphism between $\mathfrak o(4,\mathbb R)$ and $\mathfrak o (3,\mathbb R) \oplus\mathfrak o (3,\mathbb R) $ Is there any way to hide your Steam status from others? Is there any way to prevent others from seeing your Steam status without removing them as a friend?   Let's say I want to play Borderlands 2 without letting some friends know. Is there any way to hide my status to prevent them from knowing I'm playing it?  Basically, what I'm asking if Steam has an "Appear Offline" option. Can I see my active diplomatic deals in Civ 6? When making deals with AI I'm having a hard time assessing if I'm already trading for the resource or not. Is there a way I can see my currently active deals or deal history?  If not, is there a way I can see which resources I am currently importing? Clip vector on Geoprocesing QGIS 2.18.13, global name 'features' is not defined I want to clip a vector polygon with a boundary vector polygon but the process is failing. I am getting the error, "global name 'features' is not defined See log for more details". I don't know what is causing this error. In a tennis tournement of 128 players, elimination system, what is the probability that two twins will meet at some point? Why use a z test rather than a t test with proportional data?