“It is also worth noting that the earth gravitational field though locally ‘vertical’ is globally radial as the centrifugal field in the carrousel is. However, the big difference between the two is that the former decreases in intensity with distance from its center, while the latter increases its intensity with distance from the rotation center. But … (think about it a little), the farther from the center of rotation, the closer we are to the rest of the Universe!”

“The universal character of the centrifugal forces leaves us impotent as to discern whether what is going on inside the carrousel is because we are rotating with respect to terra firma (remember my eyes are closed), or because – for some unknown reason unrelated to motion – radial gravitational field has temporarily emerged while the carrousel is as in repose as it was before the given impulse. The latter would have certainly been the interpretation adopted by an intelligent being, had s/he been born and grown up inside the carrousel, without any access whatsoever to the exterior world.”

“When we say two bodies 'touch', what we mean (without knowing it) is that both electromagnetic fields are interacting to avoid physical interpenetration and ... that happens well before subatomic particles touch!”

“As we already pointed out, 'special' means 'restricted to Inertial Frames of Reference', i.e. this theory cannot describe the Universe from an arbitrary reference frame. This restricted scope is not to be ignored, though not overemphasized either. ...Ironically, and precisely because of the great success of this simple version of Relativity Theory, most of its detractors have chosen to ignore (out of ignorance or malice -- you judge case by case) its philosophical foundation and restriction to Inertial Frames, so as to declare it invalid.”

“... One can know very much but comprehend very little and, besides, ... different objectives require different levels of knowledge - though always with the maximum possible comprehension suited to the purpose.”

“The notion of Local Inertial Frame is crucial to understanding Nature and, in particular, General Relativity. Notwithstanding, very few popular science books (not even textbooks) emphasize enough its fundamental character.”

“Such is how Science makes progress: not destroying the past, but learning from it, and building on it.”