I find the whole idea of 10 being related to 7 to be utterly ridiculous. It's an insult to both games' storylines (or more like a compliment to 10's because it sucked to begin with). Thinking up theories to make the 10-7 relation seem more sensible is stupid (I'm not trying to attack anyone here), at least I think so.

Quote Originally Posted by Aralith
Well, perhaps not beaming, but maybe a method similar to the way Jenova came onto the Planet. They mention a few times throughout the game that Jenova came on a large meteor. This would explain how she was able to travel from planet to planet.
If the Cetra were capable of traveling through space, then they had to have done it in some sort of spaceship where there was air present. I like the idea of them crashing there better than them "beaming down". The only problem I have with that is that it is hard for me to believe that if they were indeed capable of traveling through space, that they wouldn't have mastered the landing part of it. Especially if they were nomadic and traveled from planet to planet as you suggest.

Quote Originally Posted by Aralith
The link I'm providing below links to a thread in here about the origins of the Black Materia and the mechanics thereof.

http://forums.eyesonff.com/showthread.php?t=86600

While it is just a theory, it's a rather good one that I believe to be true as well. It describes in great length how the Black Materia might have allowed Jenova to travel from planet to planet. I contend that the Cetra could have done a similar thing, perhaps utilizing the White Materia in some way. My point is, there are lots of other ways to get around in space in the FFVII world. Ships and beaming (obviously a facetious remark) are only a few ways.
The problem I see immediately with that theory is that he says that the Black Materia was created by some sort of "Black Lifestream". The Black/Negative Lifestream did not exist until someone died from Geostigma, and Geostigma did not exist until Jenova was destroyed in the game and the Lifestream sprouted up from the planet at the end.

The FF7 Ultimania states that the Black Materia was "given" to the Cetra, not that they took it or found it after Jenova crashed there. It also does not mention anything about it being in Jenova's possesion or it (Jenova) using the Black Materia to crash into the planet.

As for the White Materia:
Quote Originally Posted by FF7 Ultimania Omega
**The White Materia: Holy** (005.3B)
The only means of opposing Meteor, the Ultimate White Magic was passed down
amongst the Ancients. It is said that when an Ancient learns of Holy in the
Forgotten Capital, prays at the water altar and their mind then links to the
Planet, Holy is thereby put into operation. Passed down through the Ancients'
generations, the White Materia came to Aerith from her mother, Ifalna, and she
kept it hidden in a ribbon in her hair.

How exactly Holy applies its power once invoked and in operation is not
definite. It is simply known that "all that is bad for the Planet will
disappear."

(Accompanying screenshot caption)
As evidence of the Planet accepting Aerith's prayer, the White Materia laying
on the water bed shines a pale green color. However, Holy's movement was being
held back by the wicked will of Sephiroth, who had called Meteor.
No where in that quote does it mention anything about the Cetra using it to travel through space and collonize other planets. It simply says it exists to counter the Black Materia, and that it destroys "all that is bad for the Planet".