>> Weight it in space (measure it's mass, to be precise).
> 3) The period goes inside the closing parenthesis.
OK, I'll even understand this is the form considered acceptable in English (as if that language could go lower in my judgment...).
But care to explain why?
The way I see the structure of the phrase is "assertion (accessory comment ) [terminator-sign]", where [terminator-sign] is the period.
Why would it be pushed inside the brackets if it does not belong in the comment?
Because it helps with physical typesetting machines. It is American English, not to be confused with English. And yes, it is illogical, and if it bothers you just put the period where it belongs.