Wednesday is a travel day for me, and one with little chance to do any posting here. I’ll leave you, then, with a quotation, and get back to normal posting tomorrow.
Interstellar travel is incredibly difficult, perhaps as difficult to us today as a flight to Mars would have appeared to Christopher Columbus or other would-be transoceanic navigators 500 years ago. Indeed, the ratio of the distance from Earth to Mars compared to Columbus’ voyage from Spain to the Caribbean — 80,000:1 — is roughly the same as the ratio of the distance to Alpha Centauri compared to a trip to Mars. Thus, the key missions required to establish humanity successively as a Type I, Type II, and Type III civilization all stand in similar relation to each other, and if the 500 years since Columbus have sufficed to multiply human capabilities to the point where we now can reach for Mars, so a similar span into the future might be expected to prepare us for the leap to the stars. Actually, it should not take so long, because with its much larger population of inventive minds and better means of communication, the Type II civilization that will spread throughout our solar system over the next several centuries should be able to generate technological progress at a considerably faster rate than was possible by the emerging Type I civilization of our recent past.
I’m all for breakthroughs in physics that will give us capabilities as yet unknown. We may well get them someday. But even without such, methods can already be seen in outline by which currently known physics and greatly developed and refined versions of currently understood engineering can get us to the stars. That development and refinement will occur as part and parcel of the process of maturation of humanity as a Type II species.
Robert Zubrin, Entering Space (2000), pp. 188-189.