Comments on: Spiraling tentacles of galactic doom! http://blogs.discovermagazine.com/badastronomy/2007/10/30/spiraling-tentacles-of-galactic-doom/ I am an astronomer, writer, and skeptic. I likes reality the way it is, and I aims to keep it that way. My real name is Phil Plait, and I run the Bad Astronomy blog. Fri, 21 Nov 2008 22:54:04 +0000 http://wordpress.org/?v=2.3.1 By: Jason Nyberg http://blogs.discovermagazine.com/badastronomy/2007/10/30/spiraling-tentacles-of-galactic-doom/#comment-53623 Jason Nyberg Tue, 26 Feb 2008 15:46:01 +0000 http://blogs.discovermagazine.com/badastronomy/2007/10/30/spiraling-tentacles-of-galactic-doom/#comment-53623 Pierre, glad to hear it. Re: the fidelity of the simulation, the galaxy hack is a poor approximation of how a real galaxy would behave, as it doesn't model the gravitational effects of the individual stars at all, only a single central point mass per galaxy. The stars are more like field "tracers"... My own version puts all the stars in a single plane, which I think results in a more coherent view of what's happening in the gravitational field. I "fix" the start conditions in other ways to produce "better" near-misses that look cooler... I have played around with Celestia a little bit. Pierre, glad to hear it.

Re: the fidelity of the simulation, the galaxy hack is a poor approximation of how a real galaxy would behave, as it doesn’t model the gravitational effects of the individual stars at all, only a single central point mass per galaxy. The stars are more like field “tracers”… My own version puts all the stars in a single plane, which I think results in a more coherent view of what’s happening in the gravitational field. I “fix” the start conditions in other ways to produce “better” near-misses that look cooler…

I have played around with Celestia a little bit.

]]> By: Pierre http://blogs.discovermagazine.com/badastronomy/2007/10/30/spiraling-tentacles-of-galactic-doom/#comment-53622 Pierre Sun, 23 Dec 2007 22:54:43 +0000 http://blogs.discovermagazine.com/badastronomy/2007/10/30/spiraling-tentacles-of-galactic-doom/#comment-53622 Thank you Jason, I successfully applied the patch. I can see the behavior of the colliding galaxies is slightly different, indeed. Still, it's clear the simulation is far from ideal, because once you look at a few runs you see that if it was correct the intergalactic space would be filled with stars flung in all directions whenever two galaxies get close, which is obviously not the case. I guess it's just a numerical problem: not enough precision in the floats that are used, and bad handling of real close encounters. Not much we can do, it's what happens when we try to model a continuous phenomena using digital approximations... Anyway. Thanks. Have you seen the program Celestia? I love it, it's great. Once you get used to how to manipulate your camera properly, it's wonderful. Thank you Jason, I successfully applied the patch. I can see the behavior of the colliding galaxies is slightly different, indeed. Still, it’s clear the simulation is far from ideal, because once you look at a few runs you see that if it was correct the intergalactic space would be filled with stars flung in all directions whenever two galaxies get close, which is obviously not the case. I guess it’s just a numerical problem: not enough precision in the floats that are used, and bad handling of real close encounters. Not much we can do, it’s what happens when we try to model a continuous phenomena using digital approximations… Anyway. Thanks.

Have you seen the program Celestia? I love it, it’s great. Once you get used to how to manipulate your camera properly, it’s wonderful.

]]> By: forrest noble http://blogs.discovermagazine.com/badastronomy/2007/10/30/spiraling-tentacles-of-galactic-doom/#comment-53621 forrest noble Sat, 03 Nov 2007 05:26:53 +0000 http://blogs.discovermagazine.com/badastronomy/2007/10/30/spiraling-tentacles-of-galactic-doom/#comment-53621 Good question, Observed galactic collisions occur at a much less frequent rate than encrouching speeds might suggest. Why? Because current theory is wrong! Why? ask me! I think some of Halton Arp's theories will prove to be right-- after his death, similar to my own theories! se la vi. forrest noble, forrest underscore forrest at netzero dot net. Good question,

Observed galactic collisions occur at a much less frequent rate than encrouching speeds might suggest. Why? Because current theory is wrong! Why? ask me! I think some of Halton Arp’s theories will prove to be right– after his death, similar to my own theories! se la vi.

forrest noble, forrest underscore forrest at netzero dot net.

]]> By: Nigel Depledge http://blogs.discovermagazine.com/badastronomy/2007/10/30/spiraling-tentacles-of-galactic-doom/#comment-53620 Nigel Depledge Wed, 31 Oct 2007 20:25:00 +0000 http://blogs.discovermagazine.com/badastronomy/2007/10/30/spiraling-tentacles-of-galactic-doom/#comment-53620 Once again, BA, thanks very much for bringing a superb astrophotograph to our attention. BTW, I have to ask the obvious question: how many times have you been pondering galactic collisions and NOT had an image of galactic collisions appear in your inbox, hmm? Once again, BA, thanks very much for bringing a superb astrophotograph to our attention.

BTW, I have to ask the obvious question: how many times have you been pondering galactic collisions and NOT had an image of galactic collisions appear in your inbox, hmm?

]]> By: ipgrunt http://blogs.discovermagazine.com/badastronomy/2007/10/30/spiraling-tentacles-of-galactic-doom/#comment-53619 ipgrunt Wed, 31 Oct 2007 16:35:17 +0000 http://blogs.discovermagazine.com/badastronomy/2007/10/30/spiraling-tentacles-of-galactic-doom/#comment-53619 I would imagine the probability of a collision between two stars is quite small "when galaxies collide" (so much space, so little mass), but has anyone actually attempted to calculate these odds? I have no idea what factors should be in such a formula. Can any of the astronomers here venture a guess? I would imagine the probability of a collision between two stars is quite small “when galaxies collide” (so much space, so little mass), but has anyone actually attempted to calculate these odds?

I have no idea what factors should be in such a formula. Can any of the astronomers here venture a guess?

]]> By: tussock http://blogs.discovermagazine.com/badastronomy/2007/10/30/spiraling-tentacles-of-galactic-doom/#comment-53618 tussock Wed, 31 Oct 2007 09:00:26 +0000 http://blogs.discovermagazine.com/badastronomy/2007/10/30/spiraling-tentacles-of-galactic-doom/#comment-53618 So, all I have to do is wait up for a billion years or so and the sky will be getting much more interesting. Cool, unless there's some sort of delay for the southern hemisphere, though NZ may have drifted north by then anyway. Might have to look it up sometime before then. So, all I have to do is wait up for a billion years or so and the sky will be getting much more interesting.

Cool, unless there’s some sort of delay for the southern hemisphere, though NZ may have drifted north by then anyway. Might have to look it up sometime before then.

]]> By: Walabio http://blogs.discovermagazine.com/badastronomy/2007/10/30/spiraling-tentacles-of-galactic-doom/#comment-53617 Walabio Wed, 31 Oct 2007 06:33:58 +0000 http://blogs.discovermagazine.com/badastronomy/2007/10/30/spiraling-tentacles-of-galactic-doom/#comment-53617 Oh Gary # 7, The Bad Astronomer has a MacBookPro. Oh Gary # 7, The Bad Astronomer has a MacBookPro.

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