My wife and I are 57 years old, so I think I can address this. We finally got the younger child through to grad school and paid off all our debt, and now we can devote our time to what we want to do. Mostly, anyway - I'd like to be doing coding for pay, but instead I do technical translation.

But in terms of study - academic work - we're free. She's got a PhD in theoretical physics and has finally had the time to start publishing, including picking up quantum chromodynamics.

I've picked up my original doctoral work, too, which was on hold for thirty years while I supported the family. I've had no problems whatsoever tackling difficult topics - in fact, I've had less difficulty. I'm calmer, partly because I have to be in order to keep my blood pressure under control. I think I can do less in any given day, but I'm not even sure about that, because when I look back at items checked off over a week or a month, it's about what I wanted to get done.

So putting off study until you're 55 is not a bad plan. Keep reading about things in the meantime, of course. Take good notes. Keep things where you can find them in ten or twenty years. Write down your daily thoughts. You'll thank yourself later, trust me on this.

Love this! I’ve been mostly doing my hobbies as work for 20 years, but I’ve been having a blast getting back to deep pure math and PL research in the last 6-12 months which absolutely topped everything. It’s fully targeted towards my business goals which is ideal for me as I need a concrete problem to solve when learning. I’m 40 and this has been intellectually more productive than anything else I’ve done (feels like x times more than what I remember). It’s exciting and inspiring to see others doing it later in life as I wish I could keep doing it too.

Thanks a lot. I really appreciate your sharings. I'm glad that both of you manage to work on things you are interested in.

Did your wife get the PHD recently or when she was young? Reading through the lines I feel it was when she was young but I could definitely be wrong.

I also feel I don't have much to write down every day. Most of the time is spent on work chores or family chores. There are a few happy moments but that's it. May I ask what type of information do you retain?

She got her PhD in 1999, shortly after the birth of the kid who just finished his first year of grad school.

Sure, you're working, I totally get that. But you're also sometimes reading about stuff relevant to your eventual academic interests, if only articles you see on HNN or whatever. Sometimes you'll have a thought in the car. Develop the habit of journaling them when they come, in some place you won't lose over the intervening years.

You will be astonished at what you both do and don't retain over those years. It's mostly still down in there somewhere, but if you've got a few clues to unravel the threads, it'll help more than you think now.

Thanks for the tip. I'm thinking maybe I should at least register for a few pre-requisite courses and see what happens. I did have a Math Master degree but I forgot pretty much everything except SV Calculus and basic Matrix computation. Or I could just use Coursera to advance my learning -- for hell, the topics I'm interested in, e.g. General Relativity, do not need experiments so I might not even need a degree.

Regarding the last paragraph -- yeah I recalled that my first programming adventure was Foxbasing in the mid 90s. I definitely forgot all of those!

Good luck to you too.

> Write down your daily thoughts.

Can you elaborate on this? What sorts of daily thoughts did you write down and how did it help you?

I keep a notebook of ideas I want to pursue later. A lot of times if you don't write them down they'll be forgotten over the years, unless they're of major importance.

Over enough years, they will be forgotten, just like the names of the people you went to school with, unless you've got a way to rehearse them.

So a million years ago (the mid-90's), I was working with Doug Hofstadter and I had some ideas I wanted to follow up. Over the intervening years of raising a family, none of which do I regret, I never had the opportunity to actually do that - but I've done a lot of pieces of it, sometimes forgetting exactly where it fit into that original big picture.

Unfortunately, a lot of those pieces were logged on paper, but I've got electronic notes from about 2011 on, and a good content index has come in really handy for pulling out earlier ideas on various topics.

I've been working on that for the past year, and also scanning in a lot of the paper notes and starting to transcribe some of them. Looking back, there are some ideas I have every five or ten years, every time thinking I'm quite innovative.

Now that I've had the time to collate all that (and to read an absolute metric ton of literature I missed, an ongoing process), I've started to make consistent progress towards my original goals.

But just as a for instance - I have my readings and research bibliography from 1995 in machine translation. Most of that is dead as Carthage from a technical standpoint, obviously, but the philosophy has been invaluable as a starting point for recalibrating where I'm going.

But I've also got a lot of notes on related projects and just noodling thoughts I've had over thirty years of driving kids around in cars. I think the most important aspect of this is just keeping your mind active and focused on the things you find interesting, even if you don't have anything like the time you'd need to pursue them properly. Because sooner or later, the stars will align and you will. And when you do, your notes will be absolutely vital.

But I'm kind of obsessive about notes, so your mileage may vary.

I’m envious, reading EGB in the ‘70s is what put me on the path of computer science. I may yet try copycat or other creative analogy project in Elixir. I have the time, I’m retired :)

For the most part I'm staying near my field of study, programming, programming languages, theory about programming etc. In that way, just about everything I see I can relate to something I've learned before, I'm in true "I've seen it all before" mode at my age. For example the pattern matching and recursion-based "looping" navigation is just like when I went through my Haskell/Ocaml/Common Lisp/Scheme phase in the mid 2000's, so it was easy to pick up. The only new part of it is the actor-based concurrency model.

My foray into Category Theory so far has been reading "The Joy of Abstraction", which is a layman's book to CT. So far what's she's written makes perfect sense and would be mostly obvious to anyone who hangs out on HN. Moving up and down various levels of abstraction, the idea of "functions", as I read this I'm basically thinking it's what I've been doing for the past 40 years, not a big deal. We'll see as I continue in it.

Circling back to the original question, it's hard to assess my learning ability since I'm not venturing out into totally new territory for me.

When you have a job it's hard to fit in as much exercise etc. as you want, it's easier when you're retired. But also when you're retired it's easy to fill the time with other things, errands, as you get older medical appointments, and motivation is a little harder since you don't have deadlines on your projects. Work comes in spurts interlaced with reading, which is important but doesn't move the projects forward.

I do exercise regularly, especially after the heart attack. "Make these changes or you'll die" makes a great motivator.

Thanks a lot. I do agree that staying in familiar ground requires less brain work.

I do agree with the "more time without a job" observation. That's part of the motivation to pick up serious stuffs when I go semi-retire.

I hope you get well (the heart attack thing), but I'm happy that you make those changes when still young (relatively).

Out of curiosity, what was the trigger for the heart attack? I see you enjoyed your work, so I wonder if the stresses were beyond that? Or was it a diet/lifestyle issue?

I’ll chime in on this - my wife and I were just talking about it yesterday.

I’m mid 50’s. I had perfect 20/20 eye sight until about age 50, and now I can’t read almost anything without reading glasses - it came on quickly, but doesn’t seem to be worsening. I’ve always been a perfect speller (for the vocabulary that I use), but I’m finding I misspell 1-3% of what I type now (not typos). I’m also starting to misread headlines which I never did before (inserting words, misreading a single critical word, etc). It does feel like a tiny bit of haze is setting in, and I feel like this is probably normal.