Relevant XKCD: https://xkcd.com/505/

Infinity by its very nature in a sense guarantees all possibilities. Perhaps even a dumb person with infinite time would recreate all technology and beyond.

It reminds me of this disturbing video.

https://www.youtube.com/watch?v=RbCerMBxUFM

One person alone on a planet is quite busy with feeding himself and all personal needs.

Not enough time for doing science.

If they are just reinventing stuff they already know about, then possibly.

If the have to start from scratch and with no prior knowledge then definitely not. Two significant drivers of invention are necessity and interactions with/observations of environmental factors and those will likely be missing.

Eg the role of cowpox in the smallpox vaccine.

While my initial reaction was "Yes", I think that it's rather "No".

There are massive amounts of things to build and stuff to discover. And almost all of it, especially the physics, chemistry etc. stuff needs experimentation. Plenty of people had died or chronically made it difficult to do anything because of scientific experiments (think of Marie Curie or imagine what happens when you try to rediscover nuclear energy).

In our scenario, we say, that the person is immortal, but it could always happen, that they get stuck with certain illnesses or co. which significantly reduces their possible auctions. at some point they may be so limited, that they cannot do certain experiments at all and get stuck there forever.

Without other people, they'd spend their entire time trying to invent something that can kill an immortal being. Whatever that takes is as far as they'd get.

As much as people on the internet love to imply they know everything I don’t think the human brain has enough neurons or any sort of capacity to deal with all of that knowledge and expertise to get even close. Even with unlimited time.

If they have almost unlimited time, I don't see why not

By themselves? I'm not entirely sure. Some manufacturing processes would be so difficult or physically demanding that they'd require someone to help. But those would be necessary to advance to the next stage of tech...

No. Think of how big the category of technology involved in keeping the human body alive. Ok our immortal wants to recreate the pacemaker but there is no one else but them around. How would that work exactly? Presumably as an immortal they wouldn't need one. So how would they test it?

Then you add in things that only make sense if there are multiple people in the world. You don't exactly need passenger side airbags if there are no passengers. Tandem bicycles would be strange for this lone immortal to make. Everything involved in childcare from the simple (how to swaddle a baby) to the surprisingly complicated (breast milk pumps) to the obvious (diapers).

Is the guy still immortal after being engulfed by the sun?

I think be smart isn't enough to find the motivation to do something. More harder is the goal and much motivations are need it. Human race actually have evolved during crieses and inventions was maded to fix immediate needs, like market at beginning of trades in the babilonian cities. One single guy left alone even with infinite time can do nothing, or actually, you say about the sun turning a red giant, he will find the way to build a rocket probably a couple of years before that happen, just in time to flew like a rat motivated by survival instinct.

Did you just start watching/reading Dr Stone?
If not, give it a shot, it's obviously not realistic but it's basically an anime answer to your question lol

Probably not if you subscribe to https://en.m.wikipedia.org/wiki/Planck%27s_principle

Thinking back about it, it's pretty much Factorio's plot, isn't it?

Hed probably go insane, but maybe? Hed have to run logistics all by himself, so possibly not.

Special productive power of cooperative labour. So, even if intellectual ability was not a limiting factor, I don't believe it would be possible. Can't prove it, though.

I think it's possible given an infinite amount of time that they could recreate any previous human technology, but would they want to?

It might get kind of boring spending every day for thousands of years just trying to recreate old technology.

Are they the last person on earth? If so I can't see anyone wasting too much time building tech meant to assist people who don't exist anymore.

I guess what I'm saying is it's pretty certain they could do it, but only if there were some motivation like saving humanity after an apocalypse

I'm going to say no. A body immune to life threatening illnesses means they cant properly test medicines and get them right. And if they're not immune, exposing themselves to life threatening illnesses will put a stopper on that when they fail to get their medicines right on tbe first go.

I think with infinite time it would probably be possible in theory, but so much of todays technology relies on economies of scale that doing it the same way would not make a lot of sense for a single person.

So A smart person would probably create technology that looks very different from the stuff we are using today