Free Nemesis by Isaac Asimov

It’s
conceivable
, however unlikely, that Nemesis and the Sun might collide, but I recognize that it’s very unlikely they will. The trouble is that a close approach, even without collision, might be fatal to Earth.”
    “How close is a close approach?”
    “I don’t know. It will take a great deal of computation.”
    “All right, then. You suggest that we take the trouble to make the necessary observations and computations and, if we find out that the situation is indeed fraught withdanger to the Solar System, then what? Do we warn the Solar System?”
    “Well yes. What choice would we have?”
    “And how would we warn them? We have no means of hypercommunication and, even if we had, they have no system for receiving hypermessages. If we sent out a luminal message of some sort—light, micro-waves, modulated neutrinos—it would take over two years to reach Earth, assuming we have a beam powerful enough, or sufficiently coherent. And even then, how would we know if they had received it? If they had and bothered to answer, that answer would take another two years to return. And what will be the final result of the warning? We will have to tell them where Nemesis is and they will see that the information is coming from that direction. The whole point of our secrecy, the whole plan for establishing a homogeneous civilization around Nemesis, free of interference, would be lost.”
    “Whatever the cost, Janus, how could you consider
not
warning them?”
    “Where’s your concern? Even if Nemesis is moving toward the Sun, how long would it take for it to reach the Solar System?”
    “It could reach the neighborhood of the Sun in five thousand years.”
    Pitt sat back in his chair and regarded Insigna with a kind of wry amusement. “Five thousand years. Only five thousand years? Look, Eugenia, two hundred and fifty years ago, the first Earthman stood on the Moon. Two and a half centuries have passed and here we are at the nearest star. Where will we be in another two and a half centuries, at this rate? At any star we wish. And in five thousand years,
fifty
centuries, we will be all over the Galaxy, barring the presence of other intelligent forms of life. We will be reaching out to other galaxies. Within five thousand years, technology will have advanced to the point where, if the Solar System were really in trouble, all its Settlements and its entire planetary population could take off for deep space and other stars.”
    Insigna shook her head. “Don’t think that technological advance means that you can empty the Solar System by a mere wave of the hand, Janus. To remove billions of people without chaos and without tremendous loss of lifewould require long preparation. If they are in mortal danger five thousand years from now, they must know
now
. It is not too soon to begin to plan.”
    Pitt said, “You have a good heart, Eugenia, so I’ll offer a compromise. Suppose we take a hundred years in which to establish ourselves here, to multiply, to build a cluster of Settlements that will be strong enough and stable enough to be secure.
Then
we can investigate Nemesis’ destination and—if necessary—warn the Solar System. They will still have nearly five thousand years in which to prepare. Surely a small delay of a century will not be fatal.”
    Insigna sighed. “Is that your vision of the future? Humanity squabbling endlessly over the stars? Each little group trying to establish itself as supreme over this star or that? Endless hatred, suspicion, and conflict, of the kind we had on Earth for thousands of years, expanded into the Galaxy for thousands more?”
    “Eugenia, I have no vision. Humanity will do as it pleases. It will squabble as you say, or it will perhaps set up a Galactic Empire, or do something else. I can’t dictate what humanity will do, and I don’t intend to try to shape it. For myself, I have only this one Settlement to care for, and this one century in which to establish it at Nemesis. By