The Sphere Observer can now be defined as a scientist trying to determine under which conditions subjective observation is scientific. I will assume here that in the distant past the Sphere Observer was familiar with the various forms and types of motion.


Given that people like us do not feel that the Earth is moving, and that we see the Sun and all the other stars orbiting around us, it seems to us that Earth, and thus the Sphere Observer, is sitting motionlessly in the centre of the universe.

Note 5 This is the geocentric world-view, formulated by Claudius Ptolemy in his Almagest, which was adhered to until the 16th century. A nice visualization of the motions of Sun and Venus from a stationary Earth can be viewed on YouTube.

If that is the case, the frame of reference of the Sphere Observer suffices. That is, his subjective observation is already scientific, as long as he takes the restricted field of view into account, that is described by his frame. It is, as mentioned earlier, the southern half of the earth's sphere and the southern part of the sky, bounded by the EW-axis, the southern horizon and the upper half of the Sun's orbit.

In this case, it will do if the Sphere Observer is realizing that he himself as a subjective scientific observer can only examine a quarter of total reality!

 

Continue to: 2.2. Reference frame rotating Earth around stationary Sun