Jason
In response to above. You have it quite well but must consider this;
It's not that 'Index of refraction can DO it', the diffractive process can do very little, it's all about the fact that the index of refraction CAN'T STOP it!
A super massive toroid black hole spits the galactic matter back out as plasma at unbelievably high energies. Remember, the jet itself is quite big, many light years wide, and it ends up millions of light years long.
The first ejections are soon decelerated to 'c'.
The next ejections go quicker (to the outside observer) as the bit they're injected IN TO is already doing nearly 'c'!, but when the reach the jet 'head' they too are slowed down by the speed limit.
The next ejections find a nice 'moving pavement' and manage to avoid the 'n' until they too reach the jet head and the speed trap! and so on.. and on.. and on.
The outer edges of the 'tubes' are being slowed down progressively by 'n' all the time, but as you say, the power of n is limited and 'spread out' compared to a smbh. It always wins in the end, but obviously can't even 'get at' the sneaky central globules to slow them down till some time after ejection.
I've just returned to the UK from the Caribb, and we found a 150mph jet stream in our favour. It was very bumpy near the edges, but we got back around an HOUR earlier. That was because we did what those crafty central globules do!!
Look at my recent post on my essay string explaining the logic of the solution. And I've just realised I haven't rated you yet - top mark coming - I hope you have for me too!
Visualise some pictures and think it through a few times and it should stick. Then you can build the hyperexpressway. Actually there is one very central to us already, but we need to get there, and ride it safely!
How does it sound now?
Best wishes
Peter