The philosophical understanding of Gödel theorems says that a theory (including Einstein's) is still not the reality.
1. The achievement of Einstein is still not final, his theory is not perfect. The most important drawback is that there is no perfectly rigid body: it has already been shown at Ehrenfest paradox. Consequently, Einstein has no standards (of metrology). (Fortunately, the God as the Creator would have ideal standards.)
2. Take the Friedman closed universe model: the volume is limited, but there is no borders. Let the matter in this model be practically absent (so you can fly forever). There is only the observer E and the observer K. Both are flying without a motor, it is the inertial movement. Since the universe is closed, then after
years (E's time) the K will be back again. Our E believes that the observer K got aged
years (since flew only the K). But K also used the Einstein's algorithm and is sure, that the E got aged
years (since flew only the E).
The stationary universe is possible due to (non-interactional) Dark Energy and Dark Matter. Thank You, the comments are welcome. Is there an Editor among You or a kind man to suggest a willing science-popular magazine for this contribution?
Further DEVELOPMENT
Suppose that according to observer M holds the Friedman metric
, where
is spherical element. The investigator E flies with constant velocity v in one direction (v in reference of M), the same time investigator K flies with same velocity but in opposite direction. Because the movement is the inertial (as the M reports), so there is no gravitational pull, so no redshift, i.e.
. With coordinate transformation a constants one can write under differentials. Therefore every investigator observes the same form of metric:
, where constant
is connected with modified size of universe. Because the metric is the same, there is no asymmetry detected and this universal twin paradox is still active.