Wikipedia

This is a good article + discussion at Cognitive Daily that focuses in large part on Wikipedia's strengths and weaknesses: Is there really wisdom in crowds?

It helps explain why some Wikipedia articles are excellent while others are hopeless.

I can hardly bring myself to read many music articles at Wikipedia these days: I grab the trivia and run with it, check it somewhere else, but too many music entries are written by The Fan who has no idea about writing a reference article. The riposte to that is, "Why don't you edit it?" but I don't have the time or energy to be constantly cleaning up this stuff, especially when The Fan is likely to go back and mess it up again anyway.

Some excerpts from Cognitive Daily's discussion:

I think Wikipedia works pretty well when it is only discussing the dry technical details of some theory, such as the lambda calculus, because only those who actually know something about it will tend to contribute. It works less well when the subject is controversial.

The key is this: if only experts are interested in a topic, then they will be the only ones to contribute. But if the topic is of interest to those who know nothing about it, that's a situation ripe for bad Wikipedia articles.

and:

They say that while Wikipedia is fine for basic factual information you might find in a newspaper, when you get to the level of serious academic research, the information quality breaks down. ...

This is very true. It's particularly true in scientific areas where there are large, vocal, pseudoscientific activists. Autism is one area. Vaccination is another. Evolution, too. This results in "edit" wars, with activists trying to push their pseudoscience. In fact, this "selection" in Wikipedia actually can work against accuracy, because the "selective forces" (I.e., editors altering or correcting what they think to be incorrect or poorly stated information) tend to favor the cranks (creationists, quacks, Holocaust deniers, 9/11 conspiracy theorists, etc.), who tend to have a lot more time and passion to edit and create Wikipedia articles than those who would remove their dubious information have to correct them. An inherent admission of this problem comes in the form of how many Wikipedia articles tend to have moratoriums on new edits in these topics.

and

The worst part of Wikipedia's physics coverage, in my experience, has been the introductory stuff. The really knowledgeable people aren't interested in writing material at the high-school level, and it's easier to write about some facet of advanced mathematics than it is to organize a useful presentation of a topic like "force" or "energy".

I suspect that this may be contributing to the woes of your "physicist friend" and his misinformed students.

and

I'd be interested to know what kinds of physics errors the students are getting from Wikipedia, and as for the historian, does he know he can correct the errors?

These are busy people, with grants and book contracts. Why would they waste their time correcting something that will likely be "corrected" back by someone with fewer qualifications but more time than them?

That's my point about music articles, though I can't say it's "grants and book contracts" holding me back.

Obscure topics can also be a problem: for some little known musicians the Wikipedia article - and its writer - might be the only source on the planet, which makes peer review almost redundant, but any little clues are valuable when you're researching a difficult topic, and if I find them at Wikipedia I'm grateful, however much I have to proceed with caution.

In spite of misgivings and annoyances, Wikipedia is still often my first stop for basic information, and if I'm lucky I'll find some decent links to use as a springboard.