The Direction of Acceleration is Up-Inertia Down. The sensation of an observer in an accelerating spacecraft is that of “being pushed down” to the floor.

 

-         When an integral member of an accelerating frame has no outside reference and cannot see herself accelerating, a released object will appear to accelerate when it is actually moving in the velocity it had attained at the point of release.

The above statement is very important to understand. An object dropped in an accelerating spaceship does not accelerate even though acceleration can be measured. If the observer in a ship with no outside reference to make comparison developed complete amnesia that observer would think that a dropped object was accelerating to some kind of magnetic floor.

An observer cannot make a determination of direction of acceleration unless he/she is completely aware of his/her own frames magnitude and direction of acceleration.

An observer inside a closed box cannot determine his or her own magnitude nor direction of velocity. (Galileo)

An observer inside of a closed box cannot observe nor directly measure his/her own magnitude nor direction of acceleration. However, that observer may make determination if he or she is actually accelerating by measuring the apparent acceleration of a released object within the box even though that object is moving at the velocity it had attained at the time of release (and is no longer accelerating). What is actually being measured is the relative motion between the two. The simple plumb bob is the initial indicator that the observer is a member of the accelerating frame (the box). The observer holding a plumb bob is therefore an integral member of an accelerating frame (the box) that is moving in a direction opposite that of which the plumb bob is pointing. The Universal Properties of Acceleration state that this phenomenon is universal and may be applied everywhere in the universe including on the surface of planets.

The above statement leads to a probability basis for even larger invisible frames.