12/16/24

Author's notes



1.

Mislabeling in Principle of Relativity diagram 
and associated text (editions 1 through 6)


Corrected diagram and associated text:



The distance from mirror QA to QB is 0.8 light second 
(contracted from 1 light second due to P's absolute speed of 0.6).

P2 is where P is at the moment his light beam reflects at QB2.  
Remember -- this is the God's eye view, where simultaneity (a moment) 
is not something that is a perception of the parties involved.  
Observations made by an omnipresent God are not dependent on the 
speed of light.  And that omnipresent being need be nothing more 
than the reader viewing this static diagram.



2.

As part of the preparation for writing my journal article, I decided 
to confirm for myself, by way of diagramming, my assumption that 
there was a necessarily unconscious skewed aiming of a pulse of
light as discussed on page 22 in the second and third editions 
(and not mentioned in the fourth and fifth editions).

But my diagram quickly confirmed that there could be no such 
unconscious skewed aiming.

Therefore, I write (conservatively) in my journal article:

"Although a moving source of light-emission cannot impart additional 
speed to light, it is reasonable that it would affect the vector 
components of the beam's motion, creating a vector component in 
the direction of motion of the source, while the perpendicular 
vector component is diminished.  A photon does, after all, have a 
non-zero amount of momentum, and we can therefore imagine that a 
moving source of emission can have an effect on light's trajectory."



3.

In editions 1 - 5, I made incorrect commentary on the role of 
acceleration on non-kinematical time-keeping.  Acceleration 
itself does not affect non-kinematical time-keeping, despite 
being otherwise indistinguishable from a gravitational field.

Acceleration does, of course, result in a change in kinematical
time-keeping.