L E C T U R E A T P O L Y T E C H N I C O F R I O D E J A N E I R O 1 0 0 5 The eminent physicist finished his lecture, referring to the three predictions of his theory susceptible to verification: that of the displacement of the orbital axis of a planet that of the bending of light rays under the influence of the Sun’s gravitational field, observable on oc- casion in eclipses and, finally, on the displacement of red rays in the light spectrum origi- nating from the Sun’s matter, when compared to the same matter on Earth. While the first two predictions were confirmed by observation, it has not yet been pos- sible to observe with precision the displacement referred to in the last prediction due to its extremely small value, which requires a more rigorous measuring tool. […]