Posts by Odysseus
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41)
Message boards :
Number crunching :
Best completion times
(Message 3295)
Posted 23 Apr 2008 by Odysseus Post: Pentium(r) II Processor 400MHz Win98, 3379sec Mac G4/400, OS 10.3, ~3740 s. |
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Message boards :
MilkyWay@home Science :
Question from Kids by Josh
(Message 3050)
Posted 6 Apr 2008 by Odysseus Post: I'd like to add that '1 light year' means the distance that light can travel in a year. In a vacuum, this is 299792458 (about 300 million) meters per second, or 670616629.38 miles per hour. […] Where “this†refers to the speed of light, symbolized by c: multiplying the above figures by the number of seconds in a year gives the distance of 9.46 trillion kilometres, or 5.88 trillion miles, that I mentioned (less precisely) upthread. Some appreciation of interstellar distances may be obtained by observing that our Moon averages about 1.5 light-seconds from Earth, the Sun 8.3 light-minutes, Neptune 4.2 light-hours, and the distant dwarf planet 90377 Sedna 7.2 light-days, while examples of bright stars include Alpha Centauri at 4.4 light-years, as mentioned above, Arcturus (Alpha Boötis) at 3.7 light-decades, Polaris (Alpha Ursae Minoris, the North Star) at 4.3 light-centuries, and Deneb (Alpha Cygni) at 3 light-millennia. |
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Message boards :
Number crunching :
New OSX App
(Message 3041)
Posted 6 Apr 2008 by Odysseus Post: Nice work! Early results show my G4s running v1.22 ten to twenty percent faster than previously but, like Harry’s, my G5 appears to have gained considerably more, nearly thirty percent. |
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Message boards :
Number crunching :
20 workunit limit
(Message 3034)
Posted 5 Apr 2008 by Odysseus Post: Make sure also that the sum of all projects’ debts is zero when you’re done. But it might make adjustments other than you would like, mightn’t it? E.g. adding debt back to the project you had just manually reduced? |
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Message boards :
MilkyWay@home Science :
Question from Kids by Josh
(Message 3005)
Posted 4 Apr 2008 by Odysseus Post: Are there any cold stars? What’s “cold†for a star is still pretty hot as far as we are concerned. Consider the element on a stove: although it’s hottest when it’s on “high†and glowing red, when it’s on “medium†and quite dark you still wouldn’t want to touch it! The coldest known ‘living’ stars are of the type called “brown dwarfsâ€: their temperatures range from about 750 K to 2200 K (825°F to 3400°F), and they cool as they age. —What is the closest star after the sun? You must be thinking of Proxima Centauri (also called Alpha Centauri C or V645 Centauri). This faint star is a member of the Rigil Kent system, which comprises a pair of rather sunlike stars (you guessed it: Alpha Centauri A & B), 4.4 LY from here, and their red-dwarf companion, just a bit closer to us at 4.2 LY. Barnard’s Star (V2500 Ophiuchi), another red dwarf, is famous for having the greatest “proper motion†of any star, but it’s about 5.9 LY from here, making it only the fourth closest to the Sun. |
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Message boards :
Number crunching :
20 workunit limit
(Message 3004)
Posted 4 Apr 2008 by Odysseus Post: Isn't there a way to go into one of the boinc files to change the LTD? Make sure also that the sum of all projects’ debts is zero when you’re done. |
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Message boards :
Number crunching :
Have not received any W/U in over a month.....
(Message 2974)
Posted 3 Apr 2008 by Odysseus Post: In the BOINC Manager, under the projects tab, i click update for MilkyWay. Then i go and check the messages tab and when it connects to the MilkyWay servers, it is requesting 0 (zero) seconds of work, aand i dont get any […] Sounds like your system has work from other projects that BOINC needs to make some progress on before downloading more MW tasks. (Climate Prediction, perhaps?) Have you checked the debt stats on that host? You might consider increasing MW’s resource share if you think it’s not getting a large enough proportion of your CPU-time. |
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Message boards :
MilkyWay@home Science :
Question from Kids by Josh
(Message 2936)
Posted 2 Apr 2008 by Odysseus Post: Why are all the stars in the night sky different sizes? Good question! Theories of how stars form are still quite speculative. Areas of space where this is believed to be happening are known (the Great Orion Nebula, M42, for example, is one of the nearest), but they’re all very far away and the processes involved take millions of years, so it’s hard to tell just what’s going on. I believe this is quite an active area of research, as today’s giant telescopes are just beginning to see sufficient detail to investigate. I guess the size of a star is generally determined by conditions in the cloud of gas and dust in which it forms: the distribution of mass, how many stars have already been created in the region, shocks and flows created by supernovae, and so on. Most of the stars we can see are bigger and brighter than the Sun, but on the other hand most of the stars in any given region of space are smaller and fainter—although there are a great many red dwarfs around, we can only see the nearest ones because they’re so dim (and even so we need to use telescopes; infra-red instruments are better at detecting these objects than optical ones are). The largest stars are thought to have very short lives, in astronomical terms, only a few million years, but they can be thousands of times brighter than the Sun and therefore visible for great distances. Medium-sized stars like the Sun last for billions of years, but small ones can be expected to keep burning much longer than the Universe has existed so far. Why do some stars twinkle and others don't? Twinkling (the technical term is “scintillationâ€) is caused by unsteadiness in the atmosphere. Since stars are far enough away to be effectively point-sources of light, it only takes a small deviation in the path of a ray to your eye for the image to be dispersed. It’s most evident near the horizon, because toward a low altitude you have to look through a lot more air than where your target is high overhead. If you look straight up and see twinkling stars, the air must be very turbulent; you might be near a source of heat that’s creating local currents. But low, bright stars are very often seen to twinkle—sometimes in multiple colours, as different wavelengths of starlight are refracted by varying amounts. Why is the galaxy so big? I don’t think anybody knows for sure. The question is similar to that of star sizes, but all on a much larger scale, with events unfolding even more slowly. Our Galaxy is one member of a cluster of galaxies of widely varying sizes—it’s one of the bigger ones—called the Local Group, which in turn is an outlying part of a super-cluster containing thousands of galaxies. It appears that the early universe was slightly uneven in consistency, and as it expanded the density variations developed into a froth-like pattern, with galaxies distributed in sheets and strands surrounding ‘bubbles’ of mostly empty space. It is quite likely that part of the Galaxy’s bulk, especially that of the disc, came from smaller neighbours that it absorbed in the past. The Magellanic Clouds, two small nearby galaxies, seem to be undergoing such a process at the moment, trailing streamers of stars and gas as tidal forces gradually pull them apart. It’s thought by some that the formation of the spiral arms that characterize galaxies like the Milky Way can be promoted by collisions with other galaxies. |
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Message boards :
Number crunching :
Increased WU Credit
(Message 2905)
Posted 30 Mar 2008 by Odysseus Post: It's a redundancy check. Each workunit gets produced twice to make sure the results agree. If there is processor error or someone is using a modified app version that doesn't produce the same results, the workunit gets trashed. Why don’t you use the usual BOINC validation system for that, issuing two tasks per WU instead of a pair of single-task WUs? Too much work for the server? |
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Questions and Answers :
Web site :
Typo on main page
(Message 2502)
Posted 22 Mar 2008 by Odysseus Post: Didn’t notice it before … but on the very next line there are two typos: a missing T in “Distributed†and a missing A in “Evaluationâ€. |
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Message boards :
Number crunching :
Milestones
(Message 2501)
Posted 22 Mar 2008 by Odysseus Post: 50,000 cobblestones as of today. |
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Message boards :
Number crunching :
Smooth sailing-Quiet board
(Message 2500)
Posted 22 Mar 2008 by Odysseus Post: I just can't babysit it 7 days a week. That usually ‘comes with the territory’ in test projects. I would suggest that users who aren’t prepared to keep a pretty close eye on things—and tolerate some crashes, lost credit, work shortages, &c.—should probably stick with mature ‘production’ projects. |
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53)
Message boards :
MilkyWay@home Science :
GECCO 2008 paper
(Message 2379)
Posted 19 Mar 2008 by Odysseus Post: Congratulations to all concerned with the publication of An Asynchronous Hybrid Genetic-Simplex Search for Modeling the Milky Way Galaxy using Volunteer Computing. One remark in particular struck me on reading the paper: “[…] BOINC is much more accessible as it is dedicated to the project at hand, while use of the BlueGene is shared among many researchers.†From a point of view shared by many—probably most—participants, this is actually far from the case: we run a variety of other BOINC-based projects as well. For example MilkyWay@home gets between one-third and about one-sixth of my attached hosts’ CPU time, and its contribution to my overall RAC is about one-tenth. Yet evidently BOINC as a system succeeds in creating the illusion of dedication from the project’s point of view, despite the partial availability of the participating hosts and the issues of volatility & heterogeneity also mentioned in the paper. IMO this constitutes a remarkable achievement. |
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Questions and Answers :
Macintosh :
Units wont upload
(Message 2284)
Posted 16 Mar 2008 by Odysseus Post: I’ve sometimes been getting long (one-week) communication deferrals from the server outages. If the tasks show long waiting times, hitting the Retry button in the Transfers pane (or Updating the project) will usually get them moving again. (Check that the servers are up first!) |
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Message boards :
MilkyWay@home Science :
Question from Kids by Josh
(Message 2283)
Posted 16 Mar 2008 by Odysseus Post: How many stars are there in the Milkyway? The Galaxy contains about two hundred billion stars. It’s in the form of a disc, nearly a hundred thousand light-years across and a couple of thousand light-years thick, bulging in the middle. (A light-year is about ten trillion kilometres, or six trillion miles.) Here's a picture of what it might look like from a distance: The Milky Way Galaxy. There’s lots more information on that page, and links to other maps. How many Constillations are there in the Milkyway? All of the stars we can see are in the Milky Way Galaxy; most of them are comparatively very near to us. Astronomers have divided the sky into 88 official constellations. Many are based on traditional patterns from ancient Mesopotamia and Greece, but there are also recent additions to fill in gaps and to cover parts of the sky that couldn't be seen from those places. The band of the Milky Way as seen encircling the sky is what the spiral arms look like from inside. The centre of the Galaxy is in the direction of Sagittarius. A Galactic Chart shows the other constellations that it passes through. |
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Message boards :
Number crunching :
More Work !!! Please :)
(Message 2238)
Posted 14 Mar 2008 by Odysseus Post: sorry for not being on but i've been sick in bed for the last couple days with some pneumonia. Take it easy now; I’m sure we’ll all understand if you can’t ‘burn the candle at both ends’ for a while. Pneumonia can be a tenacious bugger … |
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Questions and Answers :
Web site :
Website problem?
(Message 2237)
Posted 14 Mar 2008 by Odysseus Post: don't worry iv had the same message for the last 2 days i got to the stage where iv had to look at other projects just to fill in but i know it is some what disconcerting to say the least it seems that no one knows what is going on with the wu it would be nice for some ont to let us know There have been some updates posted recently in Number Crunching; apparently the administrator was away sick for a couple of days. |
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Message boards :
MilkyWay@home Science :
General Space News
(Message 2198)
Posted 13 Mar 2008 by Odysseus Post: Just a note. You could open a new thread and post all your messages in there... I second the motion. ;) It could be called “General Space News†or something … I think other research into galactic structure and the stellar population of the Milky Way, as in the Violent Universe and Rogue Stars articles, may well be worthy of special notice, but planetary science, space exploration, cosmology & what not are scarcely relevant to the ostensible topic of this forum. |
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Message boards :
Number crunching :
Cache Limit
(Message 2023)
Posted 7 Mar 2008 by Odysseus Post: Einstein@home’s quotas are per-CPU; see the recent thread from the NC forum there, Changed daily quota. |
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Message boards :
Number crunching :
Exceeded daily quota-no new work
(Message 1955)
Posted 5 Mar 2008 by Odysseus Post: Your quota should double each time you return a successful result, until it reaches its original value again. |
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