> Let's say the universe is closed. Is there any way we can make it
> open? I was thinking about reconfiguring the mass in it. (As you
> already know, I tend to side with the open universe side.)
Fun that you ask, I regularly ask how we could close an open universe :-)
I have so far not heard a good suggestion in this area, there are
unfortunately too few experts on global relativity on this list. I
think there is a theorem somewhere, mentioned in Tipler's Physics of
Immortality, that says it is not possible to open a closed universe.
This is a rebuttal to Freeman Dyson's proposal in his paper "Time
Without End" where he wonders if this is possible:
I only raise one question which may offer us a thin chance of
survival. Supposing that we discover the universe to be
naturally closed and doomed to collapse, is it conceivable
that by intelligent intervention, converting matter into
radiation and causing energy to flow purposefully on a cosmic
scale, we could break open a closed universe and change the
topology of space-time so that only a part of it would
collapse and another part of it would expand forever? I do
not know the answer to this question. If it turns out that the
universe is closed, we shall still have about 10^10 years to
explore the possibility of a technological fix that would
burst it open.
I think the basic problem is the topology change; general relativity
doesn't allow the drastic change in topology from S^3 x [0:1] to
R^4. However, all is not lost since there are plenty of people who
study how topology change could occur in quantum gravity. It it can
occur, at least we might be able to make basement universes that are
open or closed depending on our cosmological preferences.
-- ----------------------------------------------------------------------- Anders Sandberg Towards Ascension! asa@nada.kth.se http://www.nada.kth.se/~asa/ GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y