Re: Open/Closed Universe

Bradley Graham Weslake (
Wed, 26 Nov 1997 17:10:15 +1100 (EST)

> >At 17:18:46 Tue, 25 Nov 1997 +1100 (EST) Bradley Graham Weslake
> <> wrote:
> >>>>There are a multitude of other observed phenomena which align
> >>>>well with the theory of a closed universe, as well as theoretical
> >>>>reasons for believing that such a case is probable.
> >>>
> >>> Doesn't this contradict your initial statement?
> >>
> >>No it does not. In the first instance I said that *observations* tend at
> >>this stage to support an open universe. In the second instance I said
> >>that there are many *theoretical* reasons for believing a closed
> >>universe is probable.
> Don't want to nitpick too much, but your statement was "There are a
> multitude of other observed phenomena which align[sic] well with the
> theory of a closed universe, as well as theoretical reasons for believing
> that such a case is probable." (The statement this contradicts is your
> qualified admission that "...I agree that current observations tend to
> suggest an open universe...") The first part of that sentence seems
> to me to translate into there being _evidence_ for a closed universe.
> What is this evidence?

I am sorry - I used the term in it's non-empirical sense, which is what
has caused the confusion. There is such a thing as theoretical evidence
yes? I don't want to get into semantics; I concede that I worded my
statement badly. My only excuse is that I generally read the list email late
at night when, I am beginning to suspect, my mind has already began the
processes necessary for sleep.

> And why would there be good theoretical
> reasons if somewhere the theory did not match up with some facts?

If, for instance, there are fairly good empirical results from which
theoretically pleasing models can be made, but the models do not
completely and utterly explain all phenomena. This type of thing occurs
often in a science such as cosmology where a small amount of very
important observations (microwave background radiation, expanding
universe, etc.) are the basis for a great deal of theory. An analogy on
a smaller scale: we don't even understand how our own solor system
formed, even though we know a great deal about how it works.

> It appears the universe is open, but I'm interested in why, if it does,
> do some still maintain otherwise. What reasons do they have? And
> are these reasons valid and tractable? In the interim, we might do
> well to discuss/try to understand the idea of an open, globally
> hyperbolic universe -- rather than be shackled to the current
> Standard model, which might become obsolete.
> One, but by no means the only, model of an open universe is that
> of David Layzer. But even if his model is found to be faulty, any
> good theory of cosmology should be able to account for the fact
> that the universe has a lot less mass than would needed to close
> it -- given current observations.

Or be so fitted to other observations that an examination for other
matter besides the observed matter is warranted.

> Please do not take the above to mean that I think science is
> ruthlessly empirically driven. It is not -- at least, not in the
> fashion pure empiricists would have us believe. Instead, I
> think it rest not on accumulating evidence, but on
> explaining/integrating wider fields of evidence. (This is
> why, to try to add something to the quantum physics
> debate, classical mechanics has been superseded. Post-
> classical theories (QM, QFT, QED, QCD, ST, GT, etc.) are
> able to explain more with less: more facts with less ad hoc
> hypotheses.)
> An aside: What are the probabilities and how are they
> measured in this area?

Which probabilities and which area?

> Eagerly,
> Daniel Ust