The latest Carnival of Space offers several posts with an interstellar bent in addition to our own discussion, linked to from the Carnival, about antimatter rocketry and the recent thinking of JPL’s Robert Frisbee. I notice that Gerald Cleaver and Richard Obousy’s ideas about warp drive continue to get play, with particular reference to the amount of energy that this purely theoretical construct might demand. As with Alcubierre’s own warp drive speculations, the energy levels are daunting, in Cleaver and Obousy’s case the equivalent of converting the planet Jupiter into energy (that actually beats many Alcubierre demands!).
Thus NextBigFuture‘s comment, rising naturally from this conundrum:
…it makes no sense to assume being able to convert a planetary mass into energy without having increased control of technology and information and increased economy. It is like assuming a group of cavemen get the designs for a supersonic plane but only have the economy of their tribe of six to fund it. The assumptions would also be that they need to transport their rock caves and the woolly mammoths and buffalo herds that they hunt.
A point well taken, and one reason why blogger Brian Wang looks to laser propulsion as an alternative, a prospect that appeals to near-term thinkers because it takes us back into the realm of known physics. Moreover, in its various manifestations, beamed power leaves the propellant at home so that the spacecraft can carry a greater payload. What we need to learn, of course, is how sails behave in space, an examination we’ve yet to begin — let’s hope SpaceX can help us get the duplicate NanoSail-D package (whose existence was revealed in these pages) onto an upcoming Falcon flight. The ill-fated Cosmos sail built by the Planetary Society was itself capable of being used for microwave beaming experiments, and the sense here is that a world of useful experimentation awaits if we can just deploy that first true sail.
Mike Simonsen at Simostronomy takes a look at recent computer simulations from Edward Thommes and team that model planetary formation, with results that some have found unsettling:
What they found is that our solar system represents the rare cases, where gas giants form, but do not migrate to the inner planetary system, and the final orbits of the planets in the system are fairly circular and stable. In many simulations, lots of gas giants formed in chaotic environments with collisions and eccentric orbits. In other simulations, plenty of smaller rocky planets formed, but hardly any gas giants materialized out of the proto-planetary disk. Only under specific, unique conditions do planetary systems like ours evolve.
We’ve discussed the Thommes work with interest here, but failed to catch a National Science Foundation interview, in which the scientist described Earth-like planets as fairly common: “…they’re almost like weeds, they’ll sprout up under almost any conditions.” The uncommon aspect of our Solar System, then, is the existence of those gas giants in their particular orbits, posing the question of what happens to Earth-like worlds when gas giants migrate inward, as they seem to do in many simulations.
In a wider context, what happens if we do find out that a planet like ours really is rare? How would we cope with the overthrow of yet another paradigm, the Copernican perspective that has us constantly assuming we are living on an average planet in an average galaxy, and that given enough time we will inevitably find other intelligent species on similar worlds? Not that the Thommes team takes us anywhere near that conclusion, but it does offer a challenging look at planet formation theories that will only be confirmed or refuted once we have the resources in space to perform small exoplanet detections. And let’s just say it twists the tail of the Copernican assumption rather provocatively.