Originally Posted by
surgeonstone
1) doesn't matter
2) don't know
3) yes for reasons stated. Whole population data do not support their statements. Physicians, as you realize I am sure, have often been wrong.
I'm having trouble buying that your answer to 1) is truly genuine.
You would grant me that the force your brain gets exposed to in the crash is based on Delta V of your head, the change in Velocity, and Delta T, the time over which that change occurs.
I think you'd also grant me that the crushing of the foam in the helmet elongates the Delta T.
Now you can't know in advance, without mathematical values, for any given impact whether the change in Delta T from the crushing is going to be enough to make a difference in the occurence or severity of an injury, but why wouldn't you want give yourself the benefit of that ride down effect, and the chance that it maight make a difference in a particular accident?