Chalupa's dangerous idea is that, while the unrelenting barrage of neuronal activity caused by the cacophony of modern life probably eradicates any benefit presumably to be had from brain exercise, developing a habit of absolute solitude is needed to attain optimal brain performance, brain exercise or no brain exercise.
By "absolute solitude" he means no verbal interaction with another human being. No spoken, written, live, recorded or other interactions of any kind.
I suppose that could be a day alone in the wilderness with no electronics, no books, no paper to write on. Nothing. It could be a day alone at home with everything turned off and put away.
There must be lots of possibilities for achieving "absolute solitude" for a day.
What to do to fill the waking hours? That's a question that each person would need to answer for him/herself. Unless you've spent time in a monastery or in solitary confinement it's unlikely that you've had to deal with this issue. The only activity not proscribed is thinking. Imagine if everyone in this country had the opportunity to do nothing but engage in uninterrupted thought for one full day a year!
A national day of absolute solitude would do more to improve the brains of all Americans than any other one-day program. (I leave it to the lawmakers to figure out a plan for implementing this proposal.) The danger stems from the fact that a 24 period for uninterrupted thinking could cause irrevocable upheavals in much of what our society currently holds sacred. But whether that would improve our present state of affairs cannot be guaranteed.
I think the dangerousness of Chalupa's idea is mitigated by the tiny likelihood that sufficient numbers of people could be induced to participate. The idea itself, though, from an individual perspective, seems very appealing.
I'll have to try it some time. Maybe I can refine my own dangerous ideas (or better yet, dispense with them).