the little animals fly with equal speed towards all sides <strong>of</strong> the cabin. <strong>The</strong> fish swims indifferently in all directions; the drops fall into the vessel beneath; and, in throwing something at your friends, you need to throw it no more strongly in one direction than another, the distances being equal; jumping with your feet together, you pass equal spaces in every direction. When you have observed all <strong>of</strong> these things carefully (though there is no doubt that when the ship is standing still everything must happen this way), have the ship proceed with any speed you like, so long as the motion is uni<strong>for</strong>m and not fluctuating this way or that. You will detect not the least change in all the effects described, nor could you tell from any <strong>of</strong> them whether the ship was moving or standing still. 16 For the philosophers <strong>of</strong> <strong>Galileo</strong>’s times, this page is definitely revolutionary and heretical; it really establishes a new physical principle, depriving God <strong>of</strong> the fundamental property to be at absolute rest, but it does not introduce, as is generally believed erroneously, in <strong>Galileo</strong>’s mind, the principle <strong>of</strong> relativity, fully enunciated by Newton, about 60 years later, and correctly attributed to <strong>Galileo</strong> by him. This is a new fundamental paradigm, which however is not yet considered as such by the scientist who is describing it so well and clearly. On the other hand, <strong>Galileo</strong> considers the manifestation <strong>of</strong> tides as the consequence <strong>of</strong> the diurnal variation <strong>of</strong> the velocity vector on the Earth’s surface relative to a reference centered in the Sun which results by adding the centripetal motion to the tangential motion, (<strong>The</strong> resulting motion being highest at midnight and smallest a noon). For this reason the ocean’s basins, in <strong>Galileo</strong>’s mind, behave as a shaken pail in which the water moves. Thus <strong>Galileo</strong> unknowingly devises an ideal experiment that would allow an observer to establish state <strong>of</strong> rest or motion <strong>of</strong> a reference system, negating in fact the principle <strong>of</strong> relativity he had just expressed. <strong>Galileo</strong> is convinced that the manifestation <strong>of</strong> tides is the long-searched physical pro<strong>of</strong> <strong>of</strong> the Earth’s own motion substituting <strong>for</strong> the one he was never able to find, i.e. the stellar parallaxes, and derides Kepler’s hypothesis <strong>of</strong> the lunar influence on tides: But amongst all the great men who have thought about such admirable natural phenomenon, I am most surprised in Kepler, who, gifted with an independent and acute intellect, and who had originally grasped the Earth’s laws <strong>of</strong> motion, subsequently listened to and agreed with the idea <strong>of</strong> the influence <strong>of</strong> the Moon on the tides, and superstitions and other childish fads. 17 We may conclude that the trail <strong>of</strong> scientific discovery is not at all simple but as Kepler affirms Per Aspera ad Astra, i.e., it is possible to reach the stars passing through difficulties, and <strong>Galileo</strong> made a remarkable step <strong>for</strong>ward. ACKNOWLEDGEMENTS: THE AUTHOR WISHES TO THANK DR. CINZIA ZUFFADA FOR HER HELP AND SUGGESTION AND FOR TRANSLATING THE GALILEO INSERTS. 16 Galilei, G. Dialogo…. (Florence 1632) GG, VII, 212 (Translation by Cinzia Zuffada) 17 Galilei, G. Dialogo……. (Florence 1632) GG, VII, p. 486 (translation by Cinzia Zuffada) 9
Challenging the Paradigm: <strong>The</strong> <strong>Legacy</strong> <strong>of</strong> <strong>Galileo</strong> 10