Hugh Everett’s ‘many worlds’ interpretation of quantum mechanics spawned not just the idea of a multiverse, but apparently quite a few interpretations on what a multiverse implies. If you’re intrigued by the notion that our cosmos is one of what may be an infinite number of universes, you’ll want to read Dan Falk’s report in Sky & Telescope on the recent multiverse conference held at the Perimeter Institute for Theoretical Physics (Waterloo, ONT). Particularly interesting is the growth of multiverse thinking as string theory has come to the fore, with all the controversy that implies.
And then there’s the notion of ‘eternal inflation,’ which conceives of endless big bangs, each creating a separate cosmos. Laura Mersini-Houghton (University of North Carolina) is concerned about how multiverses spawned by quantum theory, string theory and inflation can be reconciled, as Falk notes:
…it’s not at all clear how these different kinds of multiverses – grounded in quite different physical theories – may be related to one another. Still, the fact that three different lines of reasoning, all rooted in modern physics, seem to be pointing the same way makes some feel there must be a connection. “My gut feeling is that these multiverses have to be related,” said Mersini-Houghton.
Nor should we forget the interesting philosophical questions such thinking suggests. What happens if every possible outcome happens with 100 percent probability? A many-worlds quantum theory leads to that result, but how does quantum theory live with the disappearance of probability itself? Hilary Greaves (Oxford) went at that one in this small session (about twenty participants) that examined not only the concept of a multiverse but the possibility that it doesn’t exist. Thus the Perimeter Institute’s own John Moffat, a specialist in general relativity, who says the multiverse “…is not the kind of science we’ve been doing since Galileo.” A good multiverse has plenty of room for skeptics.
If things closer to home carry more appeal, last month’s conference The Great Planet Debate: Science as Process got into familiar and controversial terrain in its discussion of how to define a planet. We now have eight planets as per the International Astronomical Union, but feeling at the conference seems to have been widespread in favor of revising that definition. The trick, of course, is in just how to do that. Possible definitions are all over the map, and I send you to this Planetary Science Institute news release to get the overview. Personally, I prefer the wider perspective that Larry Lebofsky (PSI) has to offer:
“We all have a conceptual image of a planet. Therefore, we need a term that encompasses all objects that orbit the Sun or other stars. The debate is a great teaching moment. Whether dwarf planets are grouped together with the classical planets is not as important as the process by which scientists arrived at their conclusions. Scientists look at the same information in different ways; there may be more than one ‘answer.’ Facts change. What we know now may not be what we know in two or three years. Learning to think critically and understanding how scientists organize facts to develop theories are lessons that will serve students for a lifetime.”
I’m assuming that what Lebofsky means is not so much that facts themselves change, but that our data continue to bring us new information about those facts. In any case, a call to think critically about the data influx is a worthwhile reminder that the way we do science carries implications for thinking and learning in any discipline.
This brief squib from the BBC relates European plans for a potential mission known as Marco Polo, now in feasibility studies. It’s an asteroid lander with the possibility of sample return, involving a small near-Earth asteroid of less than a kilometer in size. Mission launch would be approximately 2017. As I’ve often opined in these pages, an asteroid mission is a needed first step as we begin to develop the understanding — and the tools — we may one day need for possible asteroid deflection. The more we learn about the objects that could someday collide with Earth, the better prepared we’ll be should the need ever arise.