To add one more fact to what Tim has stated....By the way, I have 5 credit hours in Anatomy which qualifies me to be an expert...A brain traveling 100 mph suspended in fluid does need a "buffer". If the head is surrounded securely and with the addition of neck restraints, will not move, when the head comes to a sudden stop the brain will still impact the skull (because the brain is still traveling 100mph)....Thus, a brain injury can occur without the head making contact with an object.

Totally off this subject but having the same idea of something to slow down an impact versus a solid object to stop a car traveling 100mph....Everyone would agree that the Catch fence at Eldora and Lawrenburg are the "best" in the mid west, and almost all would agree that the Catch Fence at North Vernon(Twin City?) is the worst....Provided the front stretch has ample strength to protect the spectators....Would you rather contact a solid object at 100mph or something that would catch your car like a net (Ask Levi, the tumble he took years ago at Twin City was HUGE, but when he got to the catch fence it sit his car down like a mother laying a baby in a crib?) Maybe, just maybe, short tracks would be safer with a Catch Fence that absorbed the impact versus solid pools to contact? Also, at Twin City you are not going to bounce back to the track to have impact with other cars?