Re: [math-fun] triple star
I am curious whether anyone has done large-scale simulations of point masses in 3-space with random initial positions and velocities, under Newtonian mechanics & gravity. I'm especially curious whether that's enough for galaxy-shaped objects to appear. --Dan
I am curious whether anyone has done large-scale simulations of point masses in 3-space with random initial positions and velocities, under Newtonian mechanics & gravity.
I'm especially curious whether that's enough for galaxy-shaped objects to appear.
--Dan
I doubt that's sufficient to form galaxies, since even explanations of observed galactic rotation are unsatisfactory. Different flavors and distributions of dark matter seem to be the leading theories for reconciling observed motion, but modification of gravitational attraction at large distances also offers some theories. One interesting recent development is that all galaxies seem to have (and perhaps require) a large black hole to organize around, roughly proportional to the galactic mass. This organizing principle might even extend to globular clusters. - Scott
At 06:27 PM 6/27/2003, you wrote:
I doubt that's sufficient to form galaxies, since even explanations of observed galactic rotation are unsatisfactory. Different flavors and distributions of dark matter seem to be the leading theories for reconciling observed motion, but modification of gravitational attraction at large distances also offers some theories.
Also, galaxies don't form from individual stars. Stars are born in the dust of the galaxy.
There have been simulations of globular clusters containing thousands to millions of stars.
At 03:27 PM 6/27/2003 -0700, Scott Huddleston wrote:
... modification of gravitational attraction at large distances also offers some theories.
I was asking about this, which I think is known as MOND (Modified Newtonian Dynamics) awhile ago (October 14, 2002). What little I could find about it made it sound like it was more math than physics, in the sense that it didn't really try to give much of a physical explanation of *why* things might be that way. Yet they seem to be able to predict some observable effects (according to what little I read). Is this theory considered a contender these days, or is there some good reason it is not taken seriously? There's a web site http://www.astro.umd.edu/~ssm/mond/ which purports to give some of the basics. At least it's an interesting alternative to cold dark matter, for whatever it's worth. Shel
The answer is "yes" to both questions. This has been around for years in the computational physics/astronomy journals. --- asimovd@aol.com wrote:
I am curious whether anyone has done large-scale simulations of point masses in 3-space with random initial positions and velocities, under Newtonian mechanics & gravity.
I'm especially curious whether that's enough for galaxy-shaped objects to appear.
--Dan
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participants (6)
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asimovd＠aol.com -
Eugene Salamin -
John McCarthy -
Jud McCranie -
Scott Huddleston -
Shel Kaphan