"..contravenes the laws of physics..."
No. Think of an ejection seat.
With no (or a hard) cushion, the initial upwards acceleration of the seat is instantly (or almost instantly) transferred to the ischial tuberosities and thence to the spine and rest of body.
With a soft or air cushion, the seat starts accelerating upwards but the cushion compresses, delaying the transmission of force to the bum.
By the time the cushion is fully compressed and can transmit it's impulse to the bum, the ejection seat has already had time to accelerate quite a bit and when it finally transmits it's impulse to the bum, it is travelling a lot faster.
Much bigger shock load then, as the pioneers of ejection seat technology Like John Paul Stapp) found out to their discomfort.
Last edited by Mac the Knife; 11th Aug 2013 at 06:50.