Just how many passwords can one brain handle? Is it possible to keep stuffing in more passwords, usernames and log-in words? Or is the human brain like a suitcase, a vessel with finite space that will burst at the seams if you try to pack too much in. If someone sat on your head, would it free up more space for another few passwords? Perhaps, but then what? Where would you put the next password to come along? And the next one? And the next one? For more on this 21st-century memory problem, go here