http://archive.facepunchstudios.com/showthread/?id=443479

Ok.Here goes...
As we all know(i hope),Aperture and Black Mesa were rivals.
They were competing for federal fundings.
Now,i am gonna take you back to Half-Life:Opposing Force.

Half way in the game,you acquired the displacer gun,a very unstable portal gun designed by Black Mesa.
And when i mean unstable,it can teleport you to your death (example at the end of this)
The primary fire is a portal and on contact of any living being,it teleports them out.
If,however you miss your target and the portal hits the wall or anything like that,it will cause a shockwave of energy,turning anyone in that radius into pieces
The secondary fire teleports you anywhere,you have no control over the destination.
It brings you to parts on Black Mesa and Xen.
Now,where do i want to bring this?
THAT THE PORTAL GUN HAS A EVIL TWIN BROTHER?
No.
Here is where Aperture gets into the whole deal.
There is a photo of two Black Mesa scientists (Man and a Women)
that are in someplace with the Borealis in the background
Now,if you look into Kleiner lab and EP2 restroom,you will find a picture of the AM lab staff.
Now,you can clearly see Gordon,Kleiner and Eli.But look a little closer on the left...
Well,well!Its the same two scientist that were seen from the Borealis picture!
I deduct from this that these little buggers were spies and
told Aperture important information on Black Mesa projects.
Like,the displacer gun!As you WILL see in a photo Aperture knew about the displacer and other portal technology.So how gave the info?The spies.