Let’s say we left one single very smart guy (not necessarily with the knowledge: they may be able to understand hard stuff when taught it, but not know it already) alone on a copy of the earth. That person is also immortal. Could that person, by themselves, gain back all knowledge, maybe also experimental, or even surpass that is already available to us right now, before the planet gets inevitably engulfed by a sun turning red giant?
If he has infinite time and can’t be hurt at all I think why not. If we assume one discovery or invention takes one lifetime, and some lifetimes don’t produce inventions or discoveries because he’s working alone, he’ll still have time to gain back all the knowledge and more. Especially if he’s consciously working towards it and since he will at some point discover ways to archive information his knowledge doesn’t have to fade away. He can do pretty much anything that science allows because well he has infinite time. People seem to be stuck on collectivity but we have to depend on collective information and culture because we are mortal beings. We wouldn’t have a way to remember what previous members of society thought or did if they didn’t leave any data. It could be a different story if we experienced it ourselves
Edit: word