Warning: Undefined array key "visitor_referer_type" in /var/www/vhosts/wordinf.com/core/app/libraries/Core.php on line 98 Charles Kettering - Why is the human skull as dense as...
Why is the human skull as dense as it is? Nowadays we can send a message around the world in one-seventh of a second, but it takes years to drive an idea through a quarter-inch of human skull.