By the power of truth, I, while living, have conquered the universe.
You've clearly not paid the slightest bit of attention then...
I'v learned from the series that the forunners where the most powerful beings in the Halo universe
Wrong. The Precursors were.
prision planets.
No...
But what happend to them after that,where did they go and who where the Forunners.
Before the Didact fired the Rings, the other Forerunners were either fighting the Flood and Mendicant Bias with Offensive Bias, or they were retreating into the Shield Worlds. Once the Flood lay dormant, they reseeded the galaxy of life, passed the Mantle down to humanity to reclaim their fallen empire and left the Milky Way - likely in self-imposed exile for their failure to uphold the Mantle.
We do know that,from playing Halo Reach that Cortana is Forunner technology
Please tell me you're joking...
so that means that the Forunners are the ancestors of humans.
Again, no. The Forerunners discovered humanity, they saw us as special and passed down the Mantle to us before they left the galaxy.
In the Halo universe,the Forunners had the technology to build solar systems if not galaxies,so does that mean they created Earth.
*Yawns.*
No, the Forerunners were capable of building planets and vast structures in space. They were "world builders" (not galaxy builders), they did not create Earth.
[Edited on 12.02.2010 8:38 AM PST]