A bound state is: given a potential vanishing at infinity, negative-energy states must be bound.  How can I distinguish between a bound state and a resonance state in particles physics?
I still do not understand what a  precisely is. Is it exactly the same as a particle? Or only an excited state?  And why does it make a peak in some diagrams? And which diagrams?
Gparted: move extended partition on the left I have some free disk space on the left of my ubuntu (sda5)  What is best solution to extend sda5 ?  I can    copy sda3 or sda5 with dd to bigger disk. delete sda3,5,swap create sda3,5,swap dd original partition.   Not sure how to do it properly.  May be there is a simpler solution. After reviewing ...  I'd like to make an argument for answers that have attained more votes than an accepted answer always be ranked above when answers are being sorted by votes (the default)...     Someone visiting this (older) question expecting a relevant answer would be assuming the big green check mark means that it is the correct answer today when in fact it's the correct answer when the question was originally asked.  Allowing votes to override the asker's time bound response, it allows the best answers to remain at the top and evolve with our ever changing field without requiring the asker to maintain their questions.  This would be a step in the direction of the site's ethos in my opinion, trusting the community to determine the best answer to place at the top for prospective visitors. What can I do if I'm the victim of serial downvoting? While browsing Stack Overflow, I noticed that I lost a lot of reputation:        Is this serial downvoting? Will it be corrected by a rep-recalculation? How often are those done?    Here's a second instance: What are some important applications of the Erdős-Szekeres Theorem? There are several unknown numbers in mathematics, such as optimal constants in some inequalities. Often it is enough to some estimates for these numbers from above and below, but finding the exact values is also interesting. There are situations where such unknown numbers are necessarily natural numbers, for example in Ramsey theory. For example, we know that there is a smallest integer $n$ such that any graph with $n$ vertices contains a complete or an independent subgraph of 10 vertices, but we don't know the exact value of $n$.  What kinds of unknown small (less than 100, say) integers are there? What are the smallest unknown constants which are known to be integers? Or, more rigorously, what is the smallest upper bound for an unknown but definable number that is known to be an integer?  I know that asking for the smallest unknown integer is ill-defined since we do not know the exact values. The more rigorous version of the question is well-posed, but I do not want to keep anyone from offering interesting examples even if they are clearly not going to win the race for the lowest upper bound.  An answer should contain a definition of an integer quantity (or a family of them) and known lower and upper bounds (both of which should be integers, not infinite). Conjectures about the actual value are also welcome. I have given one example below to give an idea of what I'm looking for. How to not count blank pages in frontmatter of two-sided document Looking to Identify Book that has a large Leviathan type ship on the front The cover has a large Leviathan type ship on the front.   It is set in deep space as the people on said ship have been living there for generations. They come across an abandoned ship and set out to check it out. There are several traps but it seems to be a human ship and they even find a lone woman. Unfortunately she turns out to be an alien and attacks. They end up on a planet where a factory/warehouse is found to contain bodies, they think were eaten/experimented on by the aliens. I thought the book was called Leviathan but can't seem to find it anywhere. I seemed to be an older book from the golden age maybe even up into the 70's but I haven't had any luck yet. Any help I could get finding this would be great,thanks. What part of speech is “there” when used in “There is (blah blah)”? What part of speech is there in the sentence “There is a book on the table?”  Also, while typing it out, another question pops up vis-à-vis punctuation. In my complete first sentence above, I ended it with a question mark since my main sentence is a question. The quote is not a question, but it looks like it because of the question mark. Is this the right way to punctuate? Huge confusion with Fermions and Bosons and how they relate to total spin of atom I am supremely confused when something has spin or when it does not. For example, atomic Hydrogen has 4 fermions, three quarks to make a proton, and 1 electron. There is an even number of fermions, and each fermion has a 1/2 spin. Since there are an even number of fermions, the total spin value is an integer. This spin number is the "intrinsic" spin number that cannot be changed, but its orientation "up" or "down" can be changed.  For atomic Hydrogen, it is a Boson because it has integer spin, however it also has a single electron. I read on physics forums, , that the spin of atom comes from the electrons and not its nucleus. I also read on here, , that the spin of atomic Hydrogen is 1/2! The answer says atomic Hydrogen has spin 1/2 because it ignores the nuclear spin.  This is one thing that is confusing me. Shouldn't atomic Hydrogen have an integer spin because of the nuclear component? So does atomic Hydrogen have spin and is affected by a magnetic field? Nuclear spins are affected by magnetic fields, but they aren't as affected as electrons according to the discussion on physics forums.  Why do we ignore nuclear spin sometimes? Also, can someone help me out here with all the possibilities?  Is there a Boson with an half integer spin value? (Surely, there must not be) However atomic Hydrogen is one of those cases! (It seems...) (Why don't we cancel out the nuclear spin with the electron spin?)  Say we have another atom that is a Boson, It has unpaired electrons in different orbitals, so what determines whether or not electrons fill in orbitals as spin up or down? Does spin down nuclear spin cancel out a electron up spin? Why is ${x^{\frac{1}{2}}}$ the same as $\sqrt x $? Why is ${x^{\frac{1}{2}}}$ the same as $\sqrt x $?   I'm currently studying indices/exponents, and this is a law that I was told to accept without much proof or explanation, could someone explain the reasoning behind this.  Thank you. One server with multiple desktops "heads" with VNC I am managing a system of kiosks.  Each kiosk currently is running a web browser with the application for the kiosk running in the browser.  Each kiosk needs to be able to display separate content.  At times, the application running in the web browser freezes.  Thus, I have to go out to the site to refresh the page.  I want to see if there is a way to have one central server that has multiple browser heads.  Then each kiosk would run a program like VNC to display one of the heads.  This way when the program freezes, I just have to login to the central server and refresh the page.  Getting VNC or another remote desktop software installed on the clients is no problem.  What I am looking for is a way to have VNC remote into a specific head of a head of a web browser.  Does such a thing exist?  Or do I have to run a VM for each kiosk to remote into?  Any advice, pointers, or solutions would be helpful. View the change history of a file using Git versioning How can I view the change history of an individual file in Git, complete details with what has changed?  I have got as far as:   git log -- [filename]   which shows me the commit history of the file, but how do I get at the content of each of the file changes?  I'm trying to make the transition from MS SourceSafe and that used to be a simple right-click → show history. Does going outside of range or line of sight after casting a spell have any effect? Lost/Deleted dpkg (package manager for Debian). How do I get it back? OS: Ubuntu 12.04  Accidentally deleted dpkg. Now, packages can't be installed. So, needs an dpkg installer which installs packages. Is RSA key size the size of private key exponent? I have implemented a key pair generation scheme for RSA algorithm. I have taken the length of private key exponent as RSA key size, but then I've got to know that RSA key size is the size of the modulus $n$. Is it wrong to take RSA key size as the size of the private key exponent?  To generate a private key of 1024 bits, I increase the size of private key exponent regardless the modulus $n$. Ubuntu Detects 2 monitors when I only have one I am new to Linux and I have Ubuntu 17.04 64-bit (Budgie).  I cannot open steam. It is updated to latest version. When I open it it pops up but after some time it disappears. When I try to run it from a terminal I get this output:  tar: This does not look like a tar archive xz: (stdin): File format not recognized tar: Child returned status 1 tar: Error is not recoverable: exiting now find: ‘/home/ghazi/.steam/ubuntu12_32/steam-runtime’: No such file or directory Just recently, the right-click context menus in Windows 7 have been acting in a kind of left-handed way. That is, when possible, the initial menu appears to the left of the mouse pointer. When I hover over a submenu option, the next level of context menu appears to the left of the first and so-on.  Basically, what normally happens when you're right at the right-hand edge of the screen is happening all the time - except when I'm at the left-hand edge. Perhaps it's some kind of left-handed users option, but that doesn't seem likely - more like a right-to-left language option, except that I've never even tried to use a right-to-left language.  I haven't checked every app. for the issue - probably only Windows Explorer, definitely not in Firefox, for the moment that's as far as I've checked.  Scratch that - this affects menu bars as well as context menus. The menus dangle down to the left of the menu-bar item instead of the right, and submenus open to the left too. This seems to apply to most applications, but not too Firefox or Thunderbird.  I find this extremely annoying.  I have no idea how this occurred, though it isn't the only weird glitch I've had in Windows 7 in the last few days - see   I assume there's a setting somewhere that has got changed, but I can't find anything. There's also a chance that I've suffered some kind of registry corruption, so I might need to apply a fix in the registry - not something that scares me, but I need to know what to fix and how.  So - does anyone know what setting has been changed, and how I can fix it?  Also, beyond CCleaner (which I already have), are there any tips on making sure that the registry stays clean and sane?  Finally, both Microsoft Security Essentials and Malwarebytes Antimalware seem happy that I don't have a malware problem. Should my recent glitches make me doubt that? In many practical applications, one can consider the Earth-Centered Inertial () reference frame approximately as an inertial reference system, though strictly speaking, it is non-inertial.   Is there any quotable reference, where this claim is supported by a detailed estimation how small the effects are that one neglects if one considers the Earth's frame as inertial? Free UML drawing library for .NET