[Stephen]

Originally Posted by General Maximus

we've never heard of time crystals though so as with the spore drive, if they exist in the past why aren't they in the future? Rather than them conveniently making something up which has never existed if they need to time travel I would prefer them to use something more science and established in scifi lore and do something like a slingshot round the sun.

Who says they don't exist. Maybe the stories just didnt require them so they never needed to be mentioned.