On July 25, 2017, at 1:29 PM, Bruce  Johnson <xxxxxx@pharmacy.arizona.edu> wrote:

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>> On Jul 25, 2017, at 5:47 AM, Phil Pugliese (via tml list) <xxxxxx@simplelists.com> wrote:
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>> Even during 'The Long Night'?
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>> If they didn't have a high enough TL & "the starships just stopped coming", they wouldn't have much choice.
>> I believe in CT, TL9 allows J1 but suppose that's not good enough cuz' they's need J2+.
>> Or the system is TL8 & can't make their own J-drives?
>The Long Night is an ENTIRELY different scenario than what we were discussing. When Route 66 was supplanted by the interstate system trade didn’t cease; it merely bypassed certain areas.
>Under the pressures of the Long Night, any system that wanted or needed to build a jump drive could have put forth the effort.
>Being TL8 in the Imperium (1st, 2nd or 3rd) doesn’t mean ‘We don’t know Jump Drive exists or how to build it’; it means ‘We don’t have a Jump Drive factory in our system’. Now low-Pop TL8 world may not have that capability, but Pop9? certainly.
>It might be difficult and/or very expensive to build such a drive, but the knowledge is there, almost certainly. By the time of the Long Night, Jump Drive had been in use for MILLENNIA. The knowledge wasn’t lost. If NYC was suddenly cut off from the outside world, they wouldn’t forget how to make steel; it would just be expensive to build a plant from scratch.
>The Long Night also didn’t mean that all interstellar trade ceased; it’s just that what there was contracted enormously. The Vilani maintained a large multi-system trade network the whole time. What wasn’t there was a unified government over the entire Imperium.
>--
>Bruce Johnson
>University of Arizona
>College of Pharmacy
>Information Technology Group
>Institutions do not have opinions, merely customs
>-----
There's also another thing to consider: once you know how something is possible, you can build it with lower tech. It'll be much bulkier, and have some quirks to it, such as a computer built with colored pebbles.
A world with just steam power could be handed the engineering theory behind an M-Drive, and they could build one powered by a steam engine. It, and the power plant, would be a huge percentage of the ship,  but it would work.
It just wouldn't be economical when you have a TL9+ world within 3-5 jumps, and you can buy Imperial Standard drives from them.
But I digress. Backsliding to the level that one can't build based on engineering theory or old textbooks requires the loss of that knowledge. That requires instability, and that's something the Long Night had in plenty. Even a few generations of dealing with political instability at home, loss of economic activity, and day to day matters with no drive to go into space can cause it to become lost.