A helmets main purpose is to increase the length of time of impact. This decreases the max accel. of the brain reducing its impact against the inside of the skull. There are coup and countra coup brain strikes. The coup is when the brain injury is on the side the skull was struck in, contra coup is when the injury is opposite the strike point. If you don't think a helmet works, sign my waiver and I will gladly whack you, in the head, with a pick handle. It is hickory and has ten inches cut off the big end for a quicker swing.