Hi Derek,

The question of many universes was raised -as far as I know- in physics for the explanation of the EPR paradox. It was Hugh Everett that came with the possibility (underpinned with mathematics). Somewhere in my files I have a nice review of Everett's adventures with Wheeler and Bohr.

I simply do not know if there are other universae and the relation to physical law. In addition it is not necessary anymore to entertain this idea for the solution of the EPR paradox.

On the contrary I would propose a consistent solution of the EPR riddle by pointing at the weak interaction parity non-conservation (demonstrated in beta decay) and the fact that Lorentz invariance was introduced in the equations of quantum theory exactly to match special relativity to quantum theory. Schroedinger tried that first when he was seeking for a mathematical model but he failed.

The bi-sector hypothesis of a single universe is sufficient at this moment to explain the EPR paradox in 'classical' causal terms. The global Lorentz invariance (parity is a Lorentz transformation) is theoretical evidence. Dark matter observations could provide the experimental evidence (plus the DAMA/LiBrA observations and gravity anomalies).
 
Now that is already hard enough to understand. Not only on the level of physics but also on the more conceptual level. Aparently the paradox in quantum theory can be explained with postulating two instead of one 'sectors' in a single universe. What do we know about our single observable universe and is it already enough to say something interesting about other universae? Think about matter and anti-matter in a single universe. The bi-sector cosmology points at matter plus anti-matter in one sector and mirror matter plus mirror anti-matter in the other sector.

I think we do not know enough about the observable universe. The bi-sector explanation e.g. is already hard to grasp and experiments are very difficult to interpret. You are in Australia so you clould ask Robert Foot. He works at the astrophysics department of ANU I believe.

About the colourful Viking story. No, analytical philosophy is just one of the instruments man can use to get grasp on (his position in) the universe. Sometimes A.Phil. will be the most important thing to do, other times it could be a nuisance. Yes indeed Cosmology and Philosophy and Astrophyiscs and Astroseismology and what have you ... all contribute to the agenda of the journey. Do you think that those colourful Vikings would be arguing about whether it makes sense to repair the boat? No they would repair it and then do something else.

Now nobody can have knowledge of the he unknown. Otherwise we would not be calling that so. Agreed? I know I am on a philosophers site so this will be laughed at but try to argue against it.

I can think about what could lie ahead to plot a voyage but that does not mean to say that the Ocean is friendly enough to behave the way I think it should. Knowledge is an instrument to get somewhere. It can be a beautiful thing of art this knowledge of ours but still it is an instrument to survive.  

We learn about our own Universe by imagining different ones. In this way we could  learn why the constants are as they are and whether there are laws that remain unchanged -because otherwise no physical reality- or whether some can be changed. In that way we have learned laws of the basic fabric of physical universe. 

The Ocean so to speak will be a mystery after each next 'wave'. Do not cry about the fact that you lost sight of the shore. It is already washed away. The philosophy of washed away certainty as a replacement of the philosophy of analysis (because there is the need of something to analyse in analytic activity).

Han