I'll give the mirrors idea a little possible merit.
There are some scientific hypotheses I've read that essentially suggest that our section of the universe, the local neighbourhood of solar systems so
to speak, is in a bubble of some sort. That our bubble might be moving at a different pace or time is moving in a different manner than the universe
around it.
That we are inside of a membrane inside (inside out of?) our universe membrane.
Now why this is I suppose could be due to an external conscious act on the part of another sentience, I suppose. Why would such a sentience use
something akin to "mirrors?" Well low tech requires way less upkeep over time....maybe vast amounts of time.
What lasts longer? A well constructed foot bridge, or a super computer? Well, my computer is already on its way to being obsolete and my laptop
would have a hard time finding people skilled to still fix it or have parts available. But their are foot bridges in the World that have lasted for
millenia. That's why "low tech."








