Rifles haven't changed in 100 years
Supposedly with the human race as a whole, we double our knowledge every 7 years. * * *
Not really, ... so a quick philosophical quibble, if I may.
Not saying it's yours, but that assertion has always been an academic fiction, and not a very persuasive fiction.
It's more akin to some community college professor's off-hand remark which, over time and through repetition, eventually attained the status of an urban legend.
Your 401K, if maintained and added to, doubles every 7 years. The "human race as a whole" advances nothing. Knowledge - or at least beneficial and practical knowledge - only advances individually, when some creative thinker, inventor, craftsman, mathematician, industrialist, scientist, etc., comes up with a new idea, or a new application of an existing idea, and then pursues it to completion and success.
During the Dark & Middle Ages, the human race regressed culturally and scientifically for several
centuries from what its "collective knowledge" had been during the Greek & Roman periods. Not until the Renaissance did the (re-)discovery and dissemination of science and invention (technology) lead to a restart of human progress.
History has many similar periods where progress and the discovery and development of knowledge went stagnant for a lot more than 7 years. When you actually study history, there's nothing magical about that number as it applies to human affairs.