It _is_ special but we cannot perceive it correctly. We do not have an absolute sense of "down" (and our absolute sense of "forward" and "backward" are based on

It _is_ special but we cannot perceive it correctly. We do not have an absolute sense of "down" (and our absolute sense of "forward" and "backward" are based on a assuming fixed "down"). We sense "down" based on assuming that 1G of acceleration is the "down" position. This is fine if you're stationary. This is fine if you're moving in 2d. But accelerate in 3d and all of a sudden you can get completely disoriented because the "down" you're latching on to could be any acceleration vector. We _can_ manage this, but it is an acquired skill and we need instruments to help us. Pilots (and especially fighter pilots or astronauts who truly experience a lot of 3d acceleration) need to train for years to acquire this skill. Can you imagine training an average person years just to _use_ a jetpack? That's why we have jetpacks and yet most people don't care.