🚀 go-pugleaf

In article <C1CGp7.Jo7@well.sf.ca.us>, metares@well.sf.ca.us (Tom Van Flandern) writes:
> 
> Earlier, I wrote:
> 
> >> In short, in a big bang universe matter can change its distance in two
> >> ways: (1) directly, by the curving of spacetime by gravity, which causes
> >> matter to start moving through space; (2) indirectly, by the addition or
> >> subtraction of space between unmoving packets of matter.
> 
... stuff deleted ...
> 
>      I agree that (2) is not what GR predicts; it is what the big bang
> predicts.  I gave four citations in my previous post.  This is common
> knowledge among cosmologists.  Maybe they all have the same very common
> misconception as I do?  :-)

Actually I think it is probably a combinations of misconceptions and sloppy
analogies.  In GR (and quantum theory) on very large (and very small)
scales spacetime (particles) behaves in ways that never occur on a human
scale that we can directly experience.  Our ability to describe physics on
these scales is accurate mathematically but not linguistically.  This leads
to common misconceptions that are often fed by inadequate descriptions and
sloppy sloppy analogies.  The big bang is further complicated by multiple
equally valid metrics, ie. Friedman-Roberston-Walker and Minkowski.

GR is part of the foundation of big bang models.  The behavior of spacetime in
a big bang model is described by GR.  The analogy that an expanding universe
corresponds to a balloon with dots is only one way to view what the theory
tells us.  This analogy breaks down when applied to the solar system.  The
problem is with the analogy and not the theory.

Since we agree that option (2) is not predicted by GR, then it is also not
predicted by the big bang.  Statements that use the analogy of expanding 
spacetime are accurate only in a limited context but are often very useful in 
these contexts.  Unfortunately they can be very confusing when used in the
wrong context.  The limits of this analogy are determined by the theory.

> 
>      The big bang is not my theory -- I have no interest in this point
> beyond pinning down what the theory says so that it can be falsified. Shall
> we pose my statement to some senior big bang cosmologists and ask them if
> it is true, false, or ambiguous?  How else can we resolve this impasse?
>      -|Tom|-
> 

On the scale of the solar system a big bang model says it's all GR and GR says
its almost newtonian.

Pat