1. 2012

    Stack Exchange sends me a care package

    This is coming kind of late, because I actually received it about a week ago, but the box of stuff I got for being a moderator on Physics Stack Exchange has finally arrived!

    It includes a Physics Stack Exchange T-shirt and sticker, a generic Stack Exchange pen, Sharpie, and sticker, and a letter of appreciation from the company’s founder and CEO, Joel Spolsky.

  2. 2012

    Optimal strategy in quantum tic-tac-toe

    Here’s something I discovered recently: quantum tic-tac-toe is a variant of tic-tac-toe which allows players to make multiple moves at once, in an attempt to simulate quantum entanglement and superposition. Apparently it was invented in part to provide a way of visualizing quantum concepts. In that respect, it seems to be a decent but imperfect conceptual aid, but it’s a pretty interesting game in its own right.

    Anyway, tic-tac-toe is one of the simplest games there is, so the optimal sequence of plays have been known for a long time (in particular that if both players play optimally, the game always ends in a draw). But what about quantum tic-tac-toe? This question recently popped up on Board & Card Games Stack Exchange, and I’m rather curious to see what answers it comes up with. Currently it has a 100-point bounty attached, which means if you contribute the winning strategy, you could get 100 free reputation to get your start on Stack Exchange!

  3. 2012

    Inertia and the failure point

    Here’s one for the fellow Star Trek fans out there. At the end of Star Trek: Nemesis (SPOILER ALERT), the Enterprise-E and Shinzon’s Romulan warbird, the Scimitar, get involved in a battle in which the Scimitar latches on to the Enterprise using grips. One of the community members at Science Fiction and Fantasy Stack Exchange thought to ask, when the Scimitar fired its engines in reverse, why did it detach from the Enterprise rather than dragging both ships along?

    At the question on SFFSE, there are two proposed explanations, the inertia of the Enterprise and the failure point of the grips. Both of them are relevant, but inertia doesn’t explain what happens all by itself. After all, if it were just inertia, what’s to say that the Scimitar detaches from the Enterprise instead of the engines detaching from both ships? As we’ll see, inertia does play a role in determining how much force is exerted on each part of each of the two ships’ structures. But once that force distribution is determined, it really comes down to whether the amount of force on the grips is enough to break them.

    In the grand tradition of …

  4. 2011

    SE Chat Santa Hats

    Here’s a little treat for the holidays: add Santa hats to all the gravatars in Stack Exchange chat! You can copy and paste the CSS below into a user style, which you can enable in Firefox with the User Style Manager extension, or download a userscript that will insert the styles for you.

    This includes all the extra markup you need to copy and paste directly into Stylish:

    @namespace url(http://www.w3.org/1999/xhtml);
    @-moz-document domain("chat.stackexchange.com"), domain("chat.stackoverflow.com") {
     div.avatar {
      position: relative;
      display: block;
     div.avatar:before {
      content: url("http://static.ellipsix.net/ext-tmp/santahat32.png");
      position: absolute;
      top: -8px;
      right: 3px;
     div.avatar-16:before {
      content: url("http://static.ellipsix.net/ext-tmp/santahat16.png");
      position: absolute;
      top: -4px;
      right: 0px;
     div#active-user div.user-gravatar64:before {
      content: url("http://static.ellipsix.net/ext-tmp/santahat64.png");
      position: absolute;
      top: -18px;
      right: 0px;
  5. 2011

    Scientific Computing Stack Exchange

    I’ve occasionally posted here about my involvement with Physics Stack Exchange — in fact, don’t be too surprised to see more posts of that nature in the upcoming weeks. But today I would like to bring your attention to another potential Stack Exchange site that will be of interest to many physicists and others: Scientific Computing.

    As some of my regular readers (let us assume for the moment that these “regular readers” exist) will know, Stack Exchange is a network of question and answer websites on various topics. It started with Stack Overflow for computer programming, then expanded to Server Fault and Super User for sysadmins and power users respectively, and based on the success of that model, the people in charge have created about 70 more based on proposals from community members. The proposal for a scientific computing site came about because the topic occupies a niche between general-purpose programming and the specific science. To take computational physics as an example, these sorts of questions don’t quite fit on Physics Stack Exchange, which is about physical principles, but they don’t get a particularly good response on Stack Overflow, because they get swamped by all the questions …