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Comment: What about more complicated games (Score 1) 94

by The_Duck271 (#31916350) Attached to: Lego Robot Plays <em>Tetris</em>
A bot to do this for a more complicated games like FPSs would be interesting. To play well would involve solving a number of AI/computer vision problems. The bot would have to pick out enemies from the image it was seeing, it would have to figure out where it was on the map from visual cues and determine where to go, and so on. It would be a simplification of the problem of creating a robot that can intelligently navigate its environment, with the actual physical robot abstracted away to "push the stick forward to run."

Comment: Slower manipulation, faster thinking (Score 2, Interesting) 224

by The_Duck271 (#31195380) Attached to: Lego Robot Solves Any Rubik's Cube In 12 Seconds
Mostly this is just a demonstration of how a computer can, from the initial scrambled state, immediately see clear through to a solution in a relatively short path, whereas humans can't visualize a whole solve instantly, and so they take it in steps, at a significant cost to solution length. Comparing the two videos you can see that the human is much faster than the robot at making sequences of turns, but must make many more moves than the robot.

Comment: BattleMaster rocks (Score 1) 460

by The_Duck271 (#29716139) Attached to: Linux Games For Non-Gamers?
I'd just like to put in that BattleMaster, the game cited in the summary, is awesome. I don't play it now, but I played it for four years or so and it's excellent. It's an amazing long-term game that mixes strategy, politics, and medieval roleplaying. You're always on a team (a realm of nobles), and you're usually at war. Wars are intricate affairs lasting months and punctuated by battles every few days. Realms can be created and destroyed, and the politics of a continent will slowly shift over the years as territory changes and hand and alliances are formed and broken. For those that are into it, there is real role-playing--that is, story-telling not directly related to game strategy, unlike pretty much all so-called massively multiplayer online "role-playing" games, where the world has a story but you wouldn't know it from the way players act and talk. In BattleMaster, people act like nobles, and one actually feels immersed in a real feudal society. As the summary suggests, it needn't consume much of your time (10 or 20 minutes a day will cover you), but if you get into it it can entertain you for much longer. I hope this mention on /. gets a few people into BM.

Comment: Interferometry generates lots of data (Score 4, Informative) 186

by The_Duck271 (#29472635) Attached to: SKA Telescope To Provide a Billion PCs Worth of Processing
Some people might be interested in knowing where all this data comes from. There's a rule of thumb in astronomy that the angular resolution of your images is the wavelength of the radiation you're receive divided by the diameter of your telescope. Radio wavelengths are pretty long (up to tens of meters), so you need really big telescopes, which you get by scattering lots of little telescopes all over the place and then looking at the how the phase of the incoming radiation shifts based on location. So what you do is you sample the voltage of each antenna with 1 or 2 bits of resolution at the Nyquist frequency. So for 100Mhz radio waves you sample at 200MHz. That's 50MB/s for a single antenna. The SKA will likely have tens of thousands of little antennas scattered all over the place. So say 50MB/s times 20,000 antennas = 1TB/s = 100 petabytes/day, which is about what the summary says.

Now, it's not quite as bad as it looks. You don't have to pipe all this data to a central point to analyze it. You can take a small group of antennas and just look at the correlations between those, combine the data from that group and send the combined data to a second level of correlators, which takes data from a set of small groups, and so on, in a hierarchical fashion. You lose some information this way, but you get most of it, and the only wa to get all the information out of the data would be to bring it all to a central processing location so that data from all antennas could be compared to that of all other antennas, which is O(N^2) in the number of antennas and obviously infeasible for a telescope like the SKA. Even as it is, the system of hierarchical data collection is really pushing Moore's law, as the article shows.

Comment: Re:Speaking as a chemist (Score 5, Informative) 229

by The_Duck271 (#29424171) Attached to: Most Detailed Photos of an Atom Yet
At atomic scales electrons cannot be thought of as points; instead they are smeared out probability distributions. They don't exist at any given point, there's a chance for a given electron to be found throughout a whole region of space, and the probability of finding it at any given point is given by a probability distribution. These probability distributions are called wave functions, and given an electron's wave function you can calculate the likelihood of getting different results when you take a measurement of the electron. It is a strange aspect of quantum mechanics that you can't calculate exactly what you will measure, you can only establish the probabilities of each possible outcome.

Another aspect of quantum mechanics is that if you measure, say, the energy of an electron in an atom, you can only get one of a certain set of discrete values, and never any energy in between those values. The energy of the electron is quantized. In general, if you measure an electron's energy you have a certain probability to get a result corresponding to the first energy level, a probability to find it in the second energy level, and so on. This is also the case for some other things you can measure, like angular momentum.

However, there are certain wave functions that correspond to exactly one value of energy; that is, if you have an electron with this wave function, you are guaranteed to get a certain energy value when you measure it. In fact, there is a special set of wave functions with the following three properties:
  • They each have a definite energy level.
  • They each have a definite total angular momentum around the nucleus.
  • They each have a definite angular momentum around the z axis.

These wave functions are the atomic orbitals that are so important in chemistry. If you calculate the shapes of the wave functions that satisfy these properties, you get the shapes shown on the Wikipedia page. They are listed in a table indexed by the variables n, l, and m. n corresponds to the energy level, l corresponds to the total angular momentum, and m corresponds to the angular momentum around the z axis. For example, you can see that orbitals with high m (angular momentum around the z axis), like the ones on the very right of the Wikipedia table, are sort of flattened out by the centrifugal force from spinning fast around a vertical axis.

Comment: "The good old days" (Score 1) 899

by The_Duck271 (#29419037) Attached to: How To Make Science Popular Again?
Whenever I see things like this I can't help but wonder if people aren't succumbing to the common assertion that things (scientific literacy, societal values, quality of education, etc.) used to be good, but things started going down hill this generation. Without some kind of supporting evidence my default position is to be very skeptical of this kind of assertion. What evidence shows that scientific literacy is going downhill?

"Once they go up, who cares where they come down? That's not my department." -- Werner von Braun

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