if we exist in a plane like 2d flatworlders we would be unable to perceive a
spatial 4th axis. The fact that relativistic travelers are unaware of time
dilation or that the 3 out of 4 dimensions they experience as spatial are not
the same as the ones we experience at low velocities suggests that all
dimensions are spatial. When a spaceship is at .707C it appears from our
perspective to be at 45 degrees between time and space,it starts contracting
faster and losing velocity if it goes any faster BUT from the perspective of
the spaceship occupants they are at 0 degrees -part of what they see as normal
space is OUR time axis - when they accelerate to C we see them come to a stop
while they travel into the future which they perceive as a spatial volume. I
think we have to consider the proposal that time is actually a spatial
dimension as possible.
Regards
Fran