One wonders if eventually - historians will plug all the content from a person's personal notes, their diary, their chat logs, into an LLM, and perform research by talking to the AI about the person's life?
If you trained an LLM against all the recorded discussions of Einstein - is it that different from talking to Einstein himself?
In theory, you may be able to ask the LLM about the person's life, as if it was the person, but you won't get more facts out than you provide as input. It may still make up credible info.
Regarding your last question, it wil lack an enormous ammount of data that make up a person's experience. Moreover, talking to sound like <X> isn't the same as thinking like <X>.
It reminds me of the later part of the book Accelerando, where synthetic personalities made up from historical records (could be anyone from Cleopatra to Newton) keep being reincarnated in a near, post-singularity future. They are handed out an FAQ that tries to bring them up-to-date on the current state of affairs.
Of course you can not do any research - discover new things - by doing this. The AI can only repeat what it has been fed or make up lies. You cannot discover new material by using AI.
One level further: the historian asking questions is itself an AI meaning as soon as primary sources are provided, interesting history insights flow out.
If you trained an LLM against all the recorded discussions of Einstein - is it that different from talking to Einstein himself?