Okay, my theory of subspace:
Pretty simple, actually.
1.- What is Subspace? We cannot percieve it, yet it is ubiquitous - imagine it like the solid base our four dimensional universe it built on. It's like a wooden table with a thin paper on it. Any two dimensional creature on the paper will not know of the table's existance - but will suffer the consequences if the table were removed, and also notices certain unexplainable phenomenas (for example if the table is not smooth).
2.- How do we jump 'through' subspace? Our three dimensional room is bent, it is 'folded' in many different ways. Planets, or large gravitational centres create curvatures in the three dimensional room, like this:
Theres a couple of 'weak spots' in the structure of our universe, and they are near the heavy gravitational centres. This will thus be the ideal location for a subspace jump. The barrier will be a lot easier to pass, as the bent room will 'help you' to get into subspace.
Now, if you pierce a hole into subspace, connecting the universe with itself (connecting two 'layers' of our space)
you will open a vortex, a temporary tunnel through subspace.
The more stable a node, the weaker the barrier is, and the easier you will be able to make the connection.
A good example is a MOSFET transistor.
the voltage that needs to be present for it to be conductive is represented by the gravitation, the channel you're flying through by the channel of electrons forming up between source and drain.
3.- So what are we flying through? We're flying through a thin tunnel of 'normal space' inside subspace, through a link between two different parts of our three dimensional room. If a ship would enter subspace itself it would immediately be destroyed (or rather, be 'neutralised')
Thats why all weapons work normally, why you can fly around, and why you can do everything normally.
Now the big question 'why do shields not work in subspace?' is pretty easy. The two concepts of subspace and shield technology prevent each other from working. A shield works by creating a field around your ship. Now, a subspace drive gets all the atoms and molecules in your ship to a certain circulate vibration, to synchronize your ships 'movements' with those of subspace, as subspace has a very stong field effect itself (which is what holds the tunnel open, if used correctly) - so any attempt to create a shield there is doomed to fail.
note: I can't explain today, and my language is messed up, so i'll probably try again later.
