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Posts by Emanuel

1) Message boards : News : N-body screensaver available for testing (Message 54421)
Posted 15 May 2012 by Emanuel
Looks like the graphics application has the wrong filename for what the app_info.xml references: it's "milkyway_nbody_graphics_0.92_windows_x86_64.exe" but should be "milkyway_nbody_graphics_0.92_windows_x86_64__mt.exe" (i.e. add __mt at the end). With that I don't get any errors in BOINC, but I haven't gotten any tasks yet.
2) Message boards : News : N-body updated to 0.2 (Message 43016)
Posted 20 Oct 2010 by Emanuel
Probably won't make any difference, but are you using the TDM-GCC builds? (for MinGW)

This question is for whom?

For Matt, in reply to:
MinGW seems to not support OpenMP, so Windows will be later.
3) Message boards : News : updated the CPU applications (Message 43015)
Posted 20 Oct 2010 by Emanuel
Thanks :) Maybe this topic could be updated to point to the new link? source code and sample workunits
4) Message boards : News : updated the CPU applications (Message 43004)
Posted 20 Oct 2010 by Emanuel
Will the updated code be added to the code release repository?
5) Message boards : News : N-body updated to 0.2 (Message 42976)
Posted 19 Oct 2010 by Emanuel
Probably won't make any difference, but are you using the TDM-GCC builds? (for MinGW)
6) Message boards : News : Standalone screensaver test available for Linux (Message 42915)
Posted 17 Oct 2010 by Emanuel
ESA's GAIA will map ~100 million stars, right? Still a long way off from all of them (and I doubt they'll all be part of the milky way), but..
7) Message boards : News : Screensaver Demo (Message 42449)
Posted 29 Sep 2010 by Emanuel
Wow, it's so psychedelic. Took me a while to figure out how to get it to work. The F keys only take effect once you actually press > or <, and once they do you can't stop it, only go faster or slower and switch between zooming in and out. F5 is a bit too fast for me, I'd recommend F4 (is this dependent on the speed of your PC?). It sort of ends up like an angry white blob - is that intended? The blue edges seem to be divided into two bands instead of a smooth transition, but maybe that's just how it works.
8) Message boards : News : Screensaver Demo (Message 42433)
Posted 28 Sep 2010 by Emanuel
Indeed, lots of pretty blue bubbly things fading in and out. They sort of form a cube together, but not really. I also managed to break it at some point - pressed > and everything went black aside from the axes at the top.
9) Message boards : News : started a new nbody search: de_nbody_model1_1 (Message 42166)
Posted 15 Sep 2010 by Emanuel
No. I only know a little bit about the search; this is Travis' area. It would be more like double precision results would only be needed as the likelihoods get closer. The float result is significantly different from the double result, but still close enough to be sort of useful. Lots of float results could be used to do a rough search, and then as the fitnesses get closer, double results would be needed.

That idea was thrown around for the other applications too, but at the time it meant setting up a second project for the single precision work. If you can make it work for the nbody search, I wonder if the other searches can switch over to a similar system?
10) Message boards : News : nbody simulation assimilator up and running (Message 41542)
Posted 18 Aug 2010 by Emanuel
I'll look into it, not quite sure how to do it to be honest. Although it doesn't seem like it would be too difficult.

Thanks :) If it turns out to be difficult to figure out, the Einstein@Home scientists should be able to help out; they allow you to disable crunching for the "Arecibo Binary Pulsar Search (STSP)" (though I wouldn't want to in that case, especially given their recent discovery!)
11) Message boards : News : nbody simulation assimilator up and running (Message 41523)
Posted 17 Aug 2010 by Emanuel
I know this is still in the testing phase, but could you add an option to the Milkyway@Home Preferences (the "Preferences for this project") to only crunch for the nbody search? I wouldn't be adding much trying to compete with the GPUs on the normal WUs.
12) Message boards : News : Screensaver Demo (Message 41268)
Posted 4 Aug 2010 by Emanuel
Wow, it's so pretty - I don't suppose you could also release a dedicated standalone version? XD
Edit: oh, or do you already intend to? I should have read your last post more carefully.
13) Message boards : Number crunching : Wu Size (Message 41006)
Posted 20 Jul 2010 by Emanuel
So yes, having longer WUs would technically increase GPU utilization slightly. But there's no simple way to artificially increase WU size - the WUs would actually have to do more calculations, or do the same calculations at a higher precision. That has already been done several times, but at this point I think you'd have to develop a more complex model to benefit from increased precision or wider strips of the sky.
14) Message boards : News : New Website Coming Soon (Message 40867)
Posted 10 Jul 2010 by Emanuel
I just noticed something that's missing from the new homepage: a 'Read More ...' button underneath long news updates. You can click on 'Comment' to go to the thread, but that's hardly an intuitive way to read all of an update.
15) Message boards : MilkyWay@home Science : Is it posible that the universe are colapsing at this very moment? (Message 40521)
Posted 18 Jun 2010 by Emanuel
It just gets to me, really annoys me, that when something doesn't seem to work in 'science' these days, the theory doesn't get reworked. It simply gets stuff added to it. Invented stuff added to it to make the equations balance. It doesn't have to be real, just an an added concept or abstraction to make the maths work.

That really isn't anything new - it's been going on as long as there have been scientific theories. Take Galileo's idea that the planets rotate around the Sun in circular orbits, for example. Because his theory wasn't quite right, natural philosophers of the time were able to keep supporting the idea of the Earth as center of the universe, and all the problems were 'explained' away as anomalies. It was only when Kepler introduced elliptical orbits that they couldn't get around it anymore, and this was a significant paradigm shift (for more on those, see Thomas Kuhn's work).

Now, I'm not saying that's a good thing. But it also doesn't mean we should throw away all our theories the moment something unexplained comes up, or we'd have nothing to fall back on. Of course string theory doesn't really fit with this as it hasn't really yielded any useful predictions despite over 30 years of work, and ideas like the anthropic principle really aren't a good sign in my opinion - it's possible that it's true, but it's entirely unhelpful.
16) Message boards : MilkyWay@home Science : Is it posible that the universe are colapsing at this very moment? (Message 40486)
Posted 17 Jun 2010 by Emanuel
Vacuum fluctuations? Theory? No facts? Not provable but invented to fill a knowledge gap?

Check out the Casimir effect.
17) Message boards : MilkyWay@home Science : Is it posible that the universe are colapsing at this very moment? (Message 40481)
Posted 17 Jun 2010 by Emanuel
If something 'logically' follows on from GR, why does it become complicated? It either is..or isn't.

If that were true, science wouldn't be nearly as difficult as it is. I highly recommend looking into emergent behavior and chaotic behavior - a good place to start would be the simple experiment of a double pendulum. I was going to recommend a very readable text I was given as part of a physics course, but unfortunately I haven't been able to find it online.

Where did the initial big bang 'singularity' suddenly appear from? Not there 1 microsecond, expanding exponentially the next.

A microsecond is a unit of time, and time is subject to relativity. The closer you get to the big bang, the bigger the concentration of mass and the more time slows down - although the singularity itself is not understood by current theories (much like black holes), you could say there -was- no 'before' the big bang, as time itself was started off by it. But I should add that some theories of quantum gravity propose a 'big bounce' instead, where the big bang is not a singular event (but that begs the question of why our universe will keep expanding unlike earlier incarnations).

So how, with any accuracy, can we predict when galaxies first formed?

In essence we just look at how fast the universe is expanding and calculate back to when all the matter we see was bunched together into a single point. Since we can look 'into the past', we can check to see if the rate of expansion then agrees with our calculations. Of course, it really depends on your definition of 'accurate', since there is still a lot of uncertainty in the age of the universe. These calculations -are- based on the assumptions that space is both isotropic and homogeneous at the largest distance scales. That is, we've no reason to assume that our solar system is in some sort of great galactic void and throwing off our calculations, or that the rate of expansion would be different beyond the visible universe. Now, if we ever did find light with a greater redshift than the calculated age of the universe should allow, scientists would have some explaining to do (in one way, the smoothness of the Cosmic Microwave Background is such a problem, and we need theories of Inflation to solve it).
18) Message boards : News : updating the stock osx/linux/windows applications (Message 40437)
Posted 16 Jun 2010 by Emanuel
Somewhat related, the just released 257.21 GeForce driver release notes mention that the driver "Adds support for CUDA Toolkit 3.1 which includes significant performance increases for double precision math operations." I imagine this probably refers to new instructions/functions rather than a significant speed-up for existing ones, unless they decided to remove the double precision operations cap for the 400 series cards. Even so, it might be worth checking out.
19) Message boards : News : MilkyWay@home screensaver coming soon (Message 40313)
Posted 10 Jun 2010 by Emanuel
The pixel-summed blur circles definitely look best, but I'd actually say the single pixel rendering looks better than the transparent blitting. Either way it looks very nice :) If the whole thing moves slowly, perhaps you could limit it to 1fps or so to get a constant framerate and limit CPU usage as much as possible? Probably best to make it a serverside preference.
20) Message boards : MilkyWay@home Science : Milkyway@Home Science status? (Message 39855)
Posted 20 May 2010 by Emanuel
any news on it?

I imagine it turned into this topic: Science Info and an Astronomy Presentation

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