The Sun in Hal Jus's day was becoming a closed star. Long since the X-rays had ceased. Gradually the ultra-light and the blue light had diminished; the red and infra- reds had been accentuated; for the light was changed by the passage through that intense gravitational field. Hal Jus had, less than two thousand years ago, predicted the exact time of the Sun's final decay. After ten more years the Sun would be unable to support its family. The planets they now inhabited--Earth, Venus and Mercury--were supported artificially. The atmospheres of all the planets had long since slowly dissipated into space, and with them had gone the water. These vital things were being replaced constantly by transmutation of the elements of the rocks of the planets. Long ages ago Earth had had a large satellite, which had been used through the ages to supply energy for the factories of man, and to supply the necessary atmosphere. The satellites of Mars had gone as had Saturn with its rings, Jupiter with its satellites, along with the asteroids; but before it escaped, much of Neptune had been freighted to the habitable planets. And now, since Mars had grown too cold, it too, was being sacrificed. Already it was honeycombed with great caverns that had been used as sources of materials and energy. Now it was being split up into small parts, and freighted to the other planets. Already the work was well under way. Mars was furthest from the sun, and smaller than either Venus or Earth. But when men were assured that there was no hope of life in the solar system for more than half a lifetime, they began an even more frantic search for still another way to overcome this last crushing blow of Nature. But at last a thing was announced that switched the endeavor of the scientists to a new line. The impossible was done. Einstein had said that it was impossible to signal faster than light. But it had at last been done. A scientist had signaled the seventy-five million miles from Earth to Venus in so short a time that the carefully prepared cathode ray oscillograph could not detect it. The signal was sent by radio and by the new method exactly simultaneously, and when they reached the station on Venus, the difference in time was just long enough for the radio to make the trip. It was a modification of something that we know in our day, a modification possible only to these descendants of ten billion years of science. Phase velocity we know. When X-Rays pass through certain materials, the index of refraction is less than one, and this can only be true if the velocity in those materials is greater than the velocity of light. The true velocity of the rays is not, but there is a second velocity, the phase velocity, that under those circumstances is greater than the velocity of light.