Help on an astronomy question.

[oldoldman]

Oh you.

[Neosutra]

To be clear, planets really only form after the second iteration of a solar system has been formed (the original cloud forms into the star -> lives a while -> explodes and sends higher order elements that were created during the fusion process into the system -> remaining cloud mass collapses down into a smaller start -> extra dust/elements in the proper orbital velocities/trajectories form into planets/heavy objects.

In the process you mentioned above, only gas giant planets or quasi stars are really formed. However the majority of the remaining dust after a stars formation collapses into the star or exits the system due to being to close or too far away from the gravitational pull.

[Max™]

Don't forget that some massive stars create multiple clouds capable of producing planetary systems which we know and love.

Current models show that the sky was once a lot more interesting, as the sun apparently had several neighbor stars within a light year or two, which have since wandered off.

Plus the pressure waves from galactic rotation can trigger a different type of second order planetary formation.

Suffice to say, it's a simple process that produces very complex results based on small permutations along the way.

As for time travel, that is a whole different matter, what aspect of it are you writing about? I usually get into these big geeky discussions on the palladium RPG message boards, when people bring up stuff like super powers or technology that would allow FTL, and I feel compelled to chime in that with a little understanding of GR, anyone with that tech/ability could plot closed timelike curves into the past.

[Neosutra]

We are all inherently time travelers.

[Mizango]

We are all inherently time travelers.

Yeppers.

[Max™]

Yeah, you'd be amazed how many people insist that time is something which happens, to which I always ask "Ok, what speed does it happen at, and do you realize by asking you that, I may as well have asked you 'What is the speed of left?' essentially?"

Everything is traveling at the speed of light through space+time, increasing motion through space reduces motion through time accordingly. When you are sitting still (ignoring the various motions of the planet/galaxy/etc), you are still moving through time.

Trivial implication of relativity, but I assume he was speaking of more interesting, though unlikely forms of time travel.

[Chicomagiko]

88mph