My brain is definitely full. Every new thing I learn comes at the expense of something else I know (I guess this should be past tense). The funny thing is I still remember when my brain had spare capacity - I used to fill it with arbitrary facts like what page I was up to when I was reading dozens of books at once. When I was young I never read one book at a time or used bookmarks. I would just remember the page I wa…
Technically, our brains do get full, even this article basically says so.
It's just that we don't experience error messages or shut down when that happens - instead, old memories are replaced with new ones.
The total capacity is limited, but the ability to create new memories is unhindered.
I wish we could choose what we forget, but it seems it's possible to choose what you remember - just relearn that stuff or recall it more often, then it will be at the top of the search results, so to say :-)