 Why had Harry left Earth?
But with the Procyon shuttle arriving yesterday, there was no telling what might turn up. For eighty years now, they’d been sending out the little ships that vanished at greater than the speed of light, equipped with every conceivable device to make them return automatically after taking pictures of wherever they arrived. So far, none had ever returned or been located. Harry had been born just before Earth passed the drastic birth limitation act and his mother had spoiled him. He had no desire to spend ninety years cooped up with a bunch of callow young emigrants, even in one of the improved Exodus shuttles. And even if Exodus ever got the super-light drive working, there was no reason he should give up his work. The discovery that men could live practically forever had put an end to most family ties; sentiment wore thin in half a century—which wasn’t much time now, though it had once seemed long enough. Earth was becoming a backwater world; no real progress had been made in two centuries; the young men were sent out as soon as their first fifty years of education were finished, and the older men were too conservative for really new thinking. That missile reached Sirius in less than ten days. It took two accidents to get the thing back to us—and with a half-light-year miss that delayed it about twenty years before the Procyon shuttle heard its signal. Dubbins was at his side almost at once, with a hand under his arm to guide him toward his suite.
 the law stated that he must leave due to overpopulation
 to get married and start a family  the law stated that he must leave due to overpopulation  he had committed a crime that required him to emigrate to another place  he had been born illegally on Earth