Really well written article, especially as someone who is interested in the topic but not an expert.
Expert: I am an expert on Dark Matter. Me: What is it? Expert: I have no idea but I think it exists. Me: Ok, you must be really smart.
My glib little dialog contains no sarcasm. No doubt they are very smart. Expertise is measured differently in different fields.
Expert on Oak Island knows all the rumors and theories but not where the treasure is. Expert flat-earther knows all the wrong facts. Expert politician might know .0001% due to the vastness of government. Experts on religion know the experts in other religions are wrong. Expert MLB hitters fail more than succeed.
I guess it gives me hope I may one day be an expert at something.
It is very difficult for a poser to fool actual experts. It is a lot easier for a poser to fool non-experts. Also it's often more lucrative.
Experts may disagree with one another without either party risking be considered non-expert by her or his peers.
Experts, also, having a decent overview of the literature (which includes observational and experimental results) will generally have a decent understanding of what they don't know. It is very rare for a poser to admit what he or she does not know. It's also fairly common for non-experts, who are not experts in some other discipline, to have no idea the amount of knowledge experts have been exposed to during the course of developing their expertise.
> No doubt they are very smart
Really, it's more that actual experts are excpetionally well-read in their narrow little disciplines, and along the way have lots of practice writing as well. The key to expertise in theoretical physics is actually reading theory (and the results of tests thereof). A lot. Writing enough will probably result in a dissertation. And, perhaps, getting a paper published, writing a book or a chapter of a textbook, and so on.
The other thing you have right is that experts can be wrong. But being wrong usually offers up an opportunity for more writing that other experts are likely to get around to reading. So being wrong can increase expertise, as one learns from others' mistakes and how they were caught, and as one thinks about how to avoid similar mistakes in the future (which offers up another opportunity for writing... and so on and so forth).
> I guess it gives me hope I may one day be an expert at something.
Noone becomes an expert without effort.
The great hitters from decades ago did not have access to video footage of themselves, their rivals, and opposing pitchers, for example. So while some of them were exceptionally skilled at hitting baseballs (and not just home runs) (and also running bases and being competent in field positions usually) they were not really experts for want of a body of rigorous literature.
Conversely, one can of course have sub-major-league skills but enormous expertise -- there are batting coaches and sports science academics after all, and even popular analysts. And sports skills decay with age.
Nobel-prize-winning scientists can get senile dementia too; sadly that not just wrecks their skills, it also wrecks their expertise as they forget much of what they've read and studied.