This has bothered me for some time, and since bad tags are on the table, I think this is a good time to do it. The original burninate request got good traction, and all that remains is to implement it.
The general-physics tag is absolutely terrible, because it adds absolutely no information. It is no more descriptive of a question than the fact that it was posted in this site. Moreover, if absolutely no other tags apply to the question, then it is essentially guaranteed to be off-topic here.
There were about fifteen questions that had that tag only, of which only this tricky example remains. There's still about thirty questions with the tag and there's a slow process to remove the tag from those questions. (That could be speeded up by just burninating the tag, as originally requested, but for some reason, despite the upvotes, it hasn't happened.)
- Update: it's done: the tag is no more. All the posts that had the tag (60 at the time this question was posted) have been retagged with more descriptive tags, and the tag is currently empty. As things stand, the tag will expire in a few days, but there's still a definite danger that some new user will re-introduce it if they can't find a tag that will fit their post.
Once that's done, though, can we blacklist the tag to make sure that it doesn't come back? Seriously, it adds nothing to the site, and it only works as a misleading marker to some people that their bad questions are on-topic here.