Getting our act together
Thanks to the existence of star catalogues, we would indeed get this kind of early warning as the light reaching us would become increasingly distorted. How much of a warning of course depends on the speed by which the black hole is moving towards us. But let us say we got two hundred years. What would we do?
Two hundred years is a lot of time from a human perspective but a second when it comes to cosmic timekeeping. In two hundred years we have moved from the first trains to Shinkansen and Maglevs, from the first manned balloon flight in 1783 to the Airbus A380, and from the prototype of the telegraph in 1828 to the Internet. On the other hand, between the year 700 A.D. and the year 900 A.D., not much improved in terms of technology. As we should know by now, progress is never inevitable or teleological but a choice that depends on our social institutions. But let’s say that we understood the danger. What would be a reasonable course of political action? Well, given the overwhelming enormity of the threat and its unambiguous nature, it is obvious that any hope of survival would depend on our ability to advance sufficiently in our understanding of the natural universe and in our ability to develop highly sophisticated technology. For this specific scenario, I could imagine two mutually supporting tracks, one into spaceflight which would examine the possibility of evacuating Earth and its inhabitants and one that would look into ways of directly changing the space-time fabric with the aim of possibly neutralizing the black hole.
Either track would require unbelievable investments to stand any chance of success. It would require nothing short of our entire global society getting its act together and putting its energy into these projects. To put hundred millions of people into school to learn physics would require again hundred millions of other people supporting them. And let’s think further about it. Would we stop fighting wars or would there be different factions fighting for different “solutions” (including religious factions suggesting that we should not do anything but rely solely on God)? Or would this be the time when we finally realized that we are one single species? More than anything, I think a threat of this magnitude would make us understand that people are an asset and not a liability, that what we call “unemployment” is a false problem and that our survival would depend on our ability to make massive social investments.
So, yes, indeed, I think humanity would stand a good chance of actually surviving. But the path to that survival would be one that would teach us what we fail to understand today: our shared cosmic vulnerability, our common interest and why we need each other. In a sense, we are in fact facing problems of this magnitude (in particular the risk of nuclear annihilation) but also other and more subtle threats such as the risk of planetary entrapment whose consequences are ultimately not that different. But still, we are so very far from getting our act together.