I don't think that anyone wants them to be easy or safe.
But the explanation from Forgotten History doesn't really work within the framework we've seen for time travel in the Trek universe.
You point to Tomorrow is Yesterday as an example. In the episode, the ship isn't so badly damaged that they can't repair it in a time where they have no facilities and this is after an unplanned slingshot. Four hours is the repair estimate from Scott.
But I did explain in the book why the Enterprise was uniquely able to withstand the stresses of a slingshot, due to the alterations its engine underwent as a result of the temporal accident in "The Naked Time." A different ship probably wouldn't have survived at all.
Maybe it's the way Starfleet is presented in the book that's the problem...
I just found it hard to believe that they couldn't figure out and replicate the experiment. And seemed to consistently leave out the new intermix formula used at PSI 2000. It just seems like they couldn't make it work but had never used another ship to attempt to replicate the first time travel incident.
You misunderstood.It's not about just using the intermix formula. It's that the formula introduced permanent changes in the Enterprise's reactor and warp coils that somehow enabled them to generate a protective chroniton field. Starfleet did try to replicate that effect multiple times, even modifying warp coils from the exact same production run as the Enterprise's warp coils (in case it was the result of some specific impurity or parameter variation in that run), but there was still something missing that they couldn't figure out how to replicate. And that's because they didn't have the theory yet. As we saw in Watching the Clock, there were certain aspects of temporal theory that weren't worked out until the latter half of the 24th century. So the T'Viss of 2383 was able to figure out how to modify the Enterprise's engines to get a desired temporal effect because she knew the right mathematics to use, because her era had the theoretical underpinning that would enable her to solve the equations. But the scientists of the 23rd century didn't have that mathematical or theoretical underpinning, so they couldn't crack the mystery.
This is how science often works. It builds on what's been established already, and sometimes the tools to solve a problem just don't exist yet. Einstein's forebears couldn't have figured out General Relativity until they'd had tensor calculus and Reimann's geometry of curved surfaces to work with, and wouldn't even have known that there was a need for a theory of relativity until they got the results of the Michelson-Morley experiment. Sometimes a problem can't be solved until the right theoretical and mathematical groundwork has been laid.
No, the Orb pretty clearly did send the Defiant back to Space Station K-7.
He's saying that the Orb did send them back Christopher. You're disagreeing with him while saying the same thing.
That explanation doesn't cover how they could slingshot around the sun in a creaky, old Bird of Prey with nothing more than some calculations by Spock unless he knew how to compensate for the differences between the BoP and the Enterprise.. If he knew how to do that, why would he keep it to himself. Would he not be duty bound to revel this information to Starfleet?
I guess it just comes down to a degree of suspension of disbelief. I'm more open to simply accepting what is shown, taking it at face value. To me, the vision of Star Trek is about the people, not making sure the tech fits into real world physics. I know it's not an either/or situation but my balance point is just in a different point than yours is.
If I can accept a red jelly that makes black holes then time travel is really not that big a deal.