When Celestial Dynamics becomes Kinematics Again - General Relativity Quotes

“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.”
― Felix Alba-Juez, When Celestial Dynamics becomes Kinematics Again - General Relativity

“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.”
― Felix Alba-Juez, When Celestial Dynamics becomes Kinematics Again - General Relativity

“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!”
― Felix Alba-Juez, When Celestial Dynamics becomes Kinematics Again - General Relativity

“Such is how Science makes progress: not destroying the past, but learning from it, and building on it.”
― Felix Alba-Juez, When Celestial Dynamics becomes Kinematics Again - General Relativity