Originally Posted by
Fyraltari
Pete's logic has some big leaps to it, though. First, the notion that a shot would be limited to lightspeed when FTL is a thing, hell the thing that started this line of thought was receiving an FTL message. Second, even if the beam does travel back through time, he assumed it did so at a one-to-one rate for no real reason. And finally he's using out-of-character knowledge.
I really don't see how the GM could have expected them to figure that out, when time travel had never even be a part of the setting beforehand!
My best guess with this is that, aside from the general ludicrousness of the ultra-laser,
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It's an attempt to set up SOMETHING so Palpatine's return can have some level of coherence. Likely with whatever mechanism is enabling time-things getting destroyed in the process, so it gets mostly ruled out.