You will go only as far as you are motivated to go.
kirkmc wrote:There's no doubt that learning is much more difficult as one ages.
I don't think that this is necessarily true. Learning, IMO, should be a lifetime pursuit, and thus become easier the older one gets since you have more knowledge and experience to draw upon. Learning is a skill that someone can develop even at an old age. I personally believe that the most inhibiting factors are time, memory, and patience/motivation. Maybe just time and patience/motivation, since there are ways to improve memory.
Bantari wrote:With age, learning gets harder.
However - this is not really such a decisive factor. You can still run fast, its just slightly more uphill.

My 2c is that it gets harder, but by no means impossible. The argument about pros is slightly off since pros usually reach the peak of their intellectual capabilities, when age lowers these capabilities, as it surely does, so the strength of a pro decreases. With amateurs, especially weak amateurs (up to low-high dan, I'd say, 5d and below) - this should not be that much of a factor since our limitation is not really our mental abilities.
Point #1:
I would say that unless you really aim at the very top level and wish to realistically devote your life to the game, the biggest obstacle is simply the time. As you get older, you find yourself to devote more and more of your time to other things: family, career, further education, putting food on the table, etc. The change is especially visible with young adults - when they finish college, when they get married, when they have the first kid, etc. This is why you have so many strong young players who seem to stagnate when they get older.
Point #2:
Another obstacle is simply motivation. You need to study more and more to get stronger and stronger.
At some level you need to study more and more to simply stay where you are. 
Taking into account that most of us don't enjoy studying hard (no matter how 'cool' we think the game is) and that motivation is derived by playing, at some point you reach a saturation point - the sweet spot of balance between how much you are willing to study vs. how much you like to play... And this usually determines the rank you finally settle on. It is different from person to person... and even from age to age.
Given the limited time stipulated by Point #1, I see Point #2 to be the decisive factor on how strong you can get, not really your age per se (although age has some influence.)
I agree with 99.9% of what you said. The only things that I disagree with are bolded and have an exclamation immediately after them. Regarding learning, see above. About the second point though, my study time for chess is practically zero. With that being said, I've stayed within a range of ELO points on FICS ever since I've signed up back in 2006. I haven't improved much. I think studying is only linked to improving, based on what I've experienced.
topazg wrote:I cannot believe someone starting at 28 can't make it to virtually professional strengths given a) enough natural talent, b) enough time, and c) enough motivation.
I agree with this. I think that motivation will go a long way in determining your final go rank.
JoazBanbeck wrote:The older ( post 35 yrs ) brain does not so much get worse as it gets different. The number of brain cells that you have maxes out sometime in your teens or early twenties at about 10^11, and weight maxes out at about 1400 grams.
We lose about a gram of brain weight every year thereafter. The is sometimes incorrectly translated to the alarming conclusion that we lose a million brain cells a day. We don't. Some of the loss is brain cells, some is glia ( the support cells ), and some is myelin ( the sheathing ).
The trade-off is that the connections get denser. You will have fewer cells, but more connections between them. You will suffer some decline in the ability for high speed linear calculations - like reading in go - but gain the ability to handle more subtle and complex ideas - like getting along with women.
You can learn go at any age. You will just learn it differently.
All very interesting. However, I would like to add one thing. The Human Brain will make all the connections it will ever make by the ripe old age of 23. Given that information, I started this game a little late at 21-22 ish.
I also want to take issue with the statement, "You will suffer some decline in the ability for high speed linear calculations". IMO, this is one of those half-truths that can be dangerous, especially if you grab the wrong half. Let me explain, in chess the young players tend to do better at tactics which are high-speed (almost) linear calculations. In the book
How to Become a Deadly Chess Tactician, the author, David LeMoir writes, "I too am a player who delights in tactical play. Particularly in my earlier days, I played daring attacking chess with little concern for the material situation on the board. As I got older (I've now passed the half-century), I started to believe that my tactical flair was receding faster than my hairline. Oddly, I think that I was wrong."
He then explains his reasoning. He spent a lot of time over the summer of 2001 collecting sacrificial games, and studying them. In his chess season when the summer ended, five games out of the first nine were sacrificial efforts. He then shows the readers three of the games, and after that he concludes that the sacrificial desire just needed to be reawakened and that he still had what it took.
I, in fact, would argue that older players learning the game will experience a similar phenomenon.
"Just compare the language learning ability of young children with adults. Why should Go be any different? The way of thinking is of course not the same but instead of learning words and phrases, you learn shapes, patterns and sequences. The aging effect could be even worse."
--entropi
"It makes sense, biologically, for children to learn quicker than adults. They're blank slates and need knowledge to survive as quickly as possible. From a certain age, when the basic patterns are there, the brain can switch focus to fine-tuning, rather than raw learning."
--HermanHiddema
It goes without saying that I think this is wrong, and I believe it all comes down to motivation. I think that adults just don't have the same fiery passion that they once did and that their children do. I know, at least from my experience, my drive for learning as I've gotten older has waned. In high school, I was more motivated so I learned at a faster pace than I do today four years later. The things that I'm motivated to learn, I still snatch up like you wouldn't believe though.
Please do not worry about whatever ceiling a twenty something start implies - just strive and enjoy the journey.
I think that everyone regardless of rank, as hard as it might be (for me it's nearly impossible), should try to achieve this level of commitment for just about anything one can accomplish.