I am currently working on a character backstory for somebody whose fictional character gets sent back in time an era before his species existed (essentially to bronze-age times or even earlier, it's not specified) and sets himself the task of building a spaceship by the time his original self is born again.
The character has been augmented in every way possible - strength, agility, intelligence - and has also been mentally force-fed every piece of knowledge known to his species. Essentially he's a true polymath by the time he has this spaceship-building task to do. He's also completely alone with no technology, not even wreckage.
I strongly suspect it's ludicrous to expect a lone character in the wilderness to build a spaceship, however much he might try to do so from the ground up, but I don't know exactly how it's ludicrous. I've tried pointing this out to my client but am having difficulty convincing him as he believes that his character could do it because he's just that much of a genius. Please can somebody help me out with specific snag points that this character would have?
Just to add to the fun, this character is also mindful that he mustn't do anything that influences the timeline.
I have tried reading up about this but haven't found any sources that give enough information about how a spaceship, or its supporting infrastructure, is made.