I'm still using Ubuntu 19.04 because it's what was current when I installed the OS but it is no longer supported so I want to upgrade to 20.04 LTS (or even just 19.10).  This should be very simple. There are loads of tutorials on how to upgrade from from 19.10 or 18.04 to 20.04. But it seems like it's not possible from 19.04. Could this be true?  If I run sudo apt upgrade I get a bunch of 404 errors because the disco archives don't seem to exist anymore. But I ran:  $ sudo apt dist-upgrade Reading package lists... Done Building dependency tree Reading state information... Done Calculating upgrade... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.  $ sudo do-release-upgrade Checking for a new Ubuntu release Your Ubuntu release is not supported anymore. For upgrade information, please visit: http://www.ubuntu.com/releaseendoflife  Please install all available updates for your release before upgrading.   I tried  $ update-manager -c   And it told me I was no longer supported and needed updates but when I said "ok" to installing updates it gave me the exact same error.  I'm not sure what to do here. I can't update any more because I can't apt update. I guess I could manually set all my apt repos to the Eoan Ermine ones and update again. Is that what I need to do? Where do I set that?
Recently I have installed an older version of Ubuntu on my old machine. Whenever I try to install any software, I get an error saying it couldn't be found:  $ sudo apt-get install vlc Reading package lists... Done                Building dependency tree        Reading state information... Done     E: Couldn't find package vlc
In superluminal phase velocities, what is it that is traveling faster than light? I understand that information cannot be transmitted at a velocity greater than speed of light. I think of this in terms of the radio broadcast: the station sends out carrier frequencies $\omega_c$ but the actual content is carried in the modulated wave, the sidebands $\omega_c\pm\omega_m$. The modulation envelop has its group velocity and this is the speed at which information is being transmitted. We also know, for example, that x-rays in glass have a phase velocity which is greater than the speed of light in vacuum.   My question is, what exactly is it that is travelling faster than the speed of light?    EDIT: I know it couldn't be anything physical as its superluminal. My problem is, what is it that has absolutely no information content yet we associate a velocity with it. Passing variable arguments to another function that accepts a variable argument list Community, please show some holiday spirit! Why does ? And more importantly: why does she not wear them?    Please, show some goddamn holiday spirit! Can we get Community to wear her hats, either randomly or through popular vote? I have an iPhone 6. How can I use two Bluetooth audio devices and the 3.5mm audio jack together? Me and my friends want to listen to music together. Two of us have Bluetooth Headphones (Beats Solo2 Wireless, Beats Studio Wireless) and one has a wired headset. Is there any way to use all three of these together? How to tell the order of a Feynman diagram? How can we know the order of a Feynman diagram just from the pictorial representation?  Is it the number of vertices divided by 2?  For example, I know that electnro-positron annihilaiton is first order:   So what's the order of, for instance, a radiative penguin diagram (below) ? Is there a word for someone who won't think critically? Is there a word for someone who won't think through issues and instead comes to others hoping that they will think for them and solve problems for them?  A word that is more specific to a lack of critical thinking skills than "lazy"? How to interpret this yum dependency error? I'm trying to install XRDP and I'm hitting the following:  [root@box ~]# yum -y install xrdp Loaded plugins: fastestmirror, langpacks Loading mirror speeds from cached hostfile  * base: centos.serverspace.co.uk  * epel: mirrors.coreix.net  * extras: mirror.sov.uk.goscomb.net  * updates: mirror.sov.uk.goscomb.net Resolving Dependencies --&gt; Running transaction check ---&gt; Package xrdp.x86_64 1:0.9.10-1.el7 will be installed --&gt; Processing Dependency: xrdp-selinux = 1:0.9.10-1.el7 for package: 1:xrdp-0.9.10-1.el7.x86_64 --&gt; Processing Dependency: xorgxrdp for package: 1:xrdp-0.9.10-1.el7.x86_64 --&gt; Running transaction check ---&gt; Package xorgxrdp.x86_64 0:0.2.10-4.el7 will be installed --&gt; Processing Dependency: xorg-x11-server-Xorg(x86-64) = 1.20.4 for package: xorgxrdp-0.2.10-4.el7.x86_64 ---&gt; Package xrdp-selinux.x86_64 1:0.9.10-1.el7 will be installed --&gt; Finished Dependency Resolution Error: Package: xorgxrdp-0.2.10-4.el7.x86_64 (epel)            Requires: xorg-x11-server-Xorg(x86-64) = 1.20.4            Installed: xorg-x11-server-Xorg-1.20.1-5.6.el7_6.x86_64 (@updates)                xorg-x11-server-Xorg(x86-64) = 1.20.1-5.6.el7_6            Available: xorg-x11-server-Xorg-1.20.1-3.el7.x86_64 (base)                xorg-x11-server-Xorg(x86-64) = 1.20.1-3.el7            Available: xorg-x11-server-Xorg-1.20.1-5.el7.x86_64 (updates)                xorg-x11-server-Xorg(x86-64) = 1.20.1-5.el7            Available: xorg-x11-server-Xorg-1.20.1-5.1.el7.x86_64 (updates)                xorg-x11-server-Xorg(x86-64) = 1.20.1-5.1.el7            Available: xorg-x11-server-Xorg-1.20.1-5.2.el7_6.x86_64 (updates)                xorg-x11-server-Xorg(x86-64) = 1.20.1-5.2.el7_6            Available: xorg-x11-server-Xorg-1.20.1-5.3.el7_6.x86_64 (updates)                xorg-x11-server-Xorg(x86-64) = 1.20.1-5.3.el7_6  You could try using --skip-broken to work around the problem  You could try running: rpm -Va --nofiles --nodigest   Now, I get that it's missing a dependency, however, it appears to be saying it requires xorg-x11-server-Xorg version 1.20.4.   It then continues to say version 1.20.1-5.6.el7_6 is installed.  From where I'm sitting, 4 is in the range 1-5 so I'm unclear what the issue is. They all seem to be for the right architecture.  Is 1-5 a version string in and of itself as opposed to a range, or -if not- what am I missing?  Solution: Thanks to , here's a workaround:     Having the same issue, I installed manually archived xorgxrdp   yum -y install https://archive.fedoraproject.org/pub/archive/epel/7/x86_64/Packages/x/xorgxrdp-0.2.9-1.el7.x86_64.rpm   then   yum -y install xrdp and it works Confidence interval for the p-value estimate when doing Monte Carlo testing The second paragraph of the  section of the Wikipedia article on resampling statistics, the values of a confidence interval for a p-value from a MC sampling is given:     After $N$ random permutations, it is possible to obtain a confidence interval for the p-value based on the Binomial distribution. For example, if after $N = 10000$ random permutations the p-value is estimated to be $\hat{p}=0.05$, then a 99% confidence interval for the true $p$ (the one that would result from trying all possible permutations) is $[0.044, 0.056]$.   What's the formula to calculate it? How are one-time pads distributed? It seems that OTP encryption is unbreakable. I have read some articles (Wikipedia, Blogpost, etc.), but I could not find any information about how they are used.  If I wanted to create a messenger service, how would I distribute the OTP keys? Both the sender and the receiver need this key before the message is sent, right?   And how do I make sure no one else gets these keys? Pure virtual destructor in C++ How to get rid of banding in illustrator while using gradient? How to get Rid of Banding in illustrator while using Gradient What are FML and BWSS? I see this ad sometimes and I would like to know what the acronyms are. Picture/Video capture programs What software options are there for taking videos and or pictures within Ubuntu (Much like Apple's Photobooth)?  Please limit one software solution per answer and include key features/description of the software I have run out of space on my WinXP virtual machine, which I only gave 10 GB space for when I created it.  Is there an easy way to increase it to, say, 20 GB?  I can't see any obvious option in VirtualBox settings.    The suggestion below gives this error  wim@wim-ubuntu:/media/data/winxp_vm$ VBoxManage modifyhd wim.vdi --resize 20000 VBoxManage: error: Cannot register the hard disk '/media/data/winxp_vm/wim.vdi' {46284957-2c09-4e70-8a49-bfbe0f7f681d} because a hard disk '/home/wim/VirtualBox VMs/winxp_vm/wim.vdi' with UUID {46284957-2c09-4e70-8a49-bfbe0f7f681d} already exists VBoxManage: error: Details: code NS_ERROR_INVALID_ARG (0x80070057), component VirtualBox, interface IVirtualBox, callee nsISupports Context: "OpenMedium(Bstr(pszFilenameOrUuid).raw(), enmDevType, AccessMode_ReadWrite, fForceNewUuidOnOpen, pMedium.asOutParam())" at line 210 of file VBoxManageDisk.cpp     Removing the .vdi from VirtualBox before calling VBoxManage command, then adding it back in, was successful.  But now I can't boot the virtual machine, I get this worrying screen:    By the way, it says FATAL: Could not read from the boot medium!  System halted.    The vdi must be reattached to the VM after VBoxManage command.  Further, the partition will need to be resized from WITHIN windows, because you will have this empty space:    I was able to resize the partition easily using a bit of freeware called . What is the relation between electromagnetic wave and photon? At the end of this nice video (), she says that  is a chain reaction of electric and magnetic fields creating each other so the chain of wave moves forward.  I wonder where the  is in this explanation. What is the relation between electromagnetic wave and photon? If I did  \setcounter{chapter}{-1} \chapter{Introduction}   then I get Chapter 0 Introduction. I just want the word Introduction, and I want it also in the contents when I use   \tableofcontents   How can I do that? Why is 128==128 false but 127==127 is true when comparing Integer wrappers in Java? Permanently turn off new Google Maps and go back to old one I found new Google Maps slow, useless (routes with only two points) and wrong. Is there any way, I can turn it off completely and go back to favored old Google Maps? Or is this &mdash; as with everything in Google &mdash; one way trip?  I found  text on this matter, but it seems useless. I have the feeling, that it discuss something completely different. It says about lite indicator in bottom-right corner. I don't have something like that. And provided links, that should switch new Google Maps engine between WebGL and canvas-based, simply doesn't work. All of them opens new window with annoying advertisment about new maps.  I even tried pasing part of URL, they're talking about (force=canvas) into any URL that my new Google Maps uses. Of course without any luck.  So... is there any way, I can get rid of new Google Maps, once and permanently?  UPDATE: In these days (April, 2015) Google , that soon new Google Maps will be the only one available. To my extremely negative surprise, this question will become invalid soon! :( What causes a black-body radiation curve to be continuous? The  (unlike the quantized emission seen from atomic spectra), is continuous over all frequencies.  Many objects approximate ideal blackbodies and have radiation curves very similar in shape and continuity to that of an ideal black-body (often minus some emission and absorption lines from the atoms in an object, such as radiation curves seen from stars).  I am wondering what exactly gives rise to a basically continuous black-body radiation curve in real objects? Since atomic energy states are quantized, it seems real life black-body curves would have some degree of measurable quantization to them (or perhaps the degree of quantization is so small the radiation curves look continuous). I have seen a "Universal Laptop Adapter" sold in a computer shop before. I am thinking of getting one for a laptop. Is it safe to use? What differences are there between one of these and a typical laptop adapter?