Re: At the edge

On 14 Jun, 15:10, Lance <LanceG...@xxxxxxxxx> wrote:
Peter Ashby wrote:
Lance <LanceG...@xxxxxxxxx> wrote:

Philip wrote:
"Lance" <LanceG...@xxxxxxxxx> wrote in message
news:1181737034.786433.320610@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Jun 11, 3:37 pm, Mark.Wri...@xxxxxxxxxxxxx wrote:
Lance <LanceG...@xxxxxxxxx> wrote:

: OK - but the measurements would still show the curvature of space that
: a doughnut would necessitate - and the articles by physicists and
: astronomers themselves say that the space in which we live seems to be
: flat - i.e., Euclidean.

How about a higher dimensional equivalent of a Mobius Strip? There are a
number of higher dimensional shapes that appear flat when viewed from the
lower dimensions because the curvature is contained entirely within the
higher dimensions.
See also:http://en.wikipedia.org/wiki/Compact_space

It seems very clever, but doesn't it fall foul of Ockham's razor?

Rather the opposite, I would have thought, since it suggests that the "edge
of the universe" and all the problematic speculations that involves is a
needless multiplication of entities.

Ah dear Philip, patronising as ever.

I would have thought the big bang theory brought all those
"problematic speculations" into being. And indeed, the same point
applies to Mark's answer. If the Big bang happened (and many
astonomers think it did), then the universe is NOT infinite, whatever
the horizon of events that we can perceive may be. And if the universe
is not infinite, then it has a boundary, even if it is not one we can
reach. So go patronise yourself for a while, do.

The problem is Lance is that your idea of an edge fails to take several
things into account.

1. Geometry of space time.

2. there can be no 'outside' to form the other side of this 'edge'

You are applying the idea of space that your brain has evolved to enable
you think about without any other tools. Cosmologists and physicists
have developed tools, largely mathematical, to enable them to think
about it differently that renders your tools inadequate. This causes
people to ask such questions as yours as well as what was there 'before'
the big bang? Such questions serve simply to display the ignorance
and/or lack of understanding of the questioner.

Peter

--
Add my middle initial to email me. It has become attached to a country
www.the-brights.net

Again you patronise me because in fact cosmologists DO ask the
questions I ask. I have, for example, seen articles by cosmologists on
the question of what came before the Big Bang - and if I recall
rightly the cosmologist speculated wildly by suggesting that the Big
Bang was just one of many that have happened in sequence.

Peter's comments are in line with the Standard Model. But that assumes
the equations of General Relativity hold all the way back to 'time
zero'. But the equations are thought to break down, and a new model is
needed for very sghort times after the Big Bang -- a Quantum
cosmology. So this allows the concept of "befoe the Big Bang" to creep
back in, and your sequential models become possible.

about what might lie outside (hence the notion of an edge) of the
universe created by the Big bang has also been considered. For example
I saw a TV program in which learned cosmologists speculated about two
or more "universes colliding", with the collision producing certain
effects in the time and space we experience. I understand that there
may be no good answers to these questions...

The problem is there are many different models, and unless you specify
your model precisely people are likely to come back with "it's a ball
there's no edge!", or "it's infinite there's no edgt!" 'cause they are
using different models. So you need to specify and ask "In Dr
Strangeboy's model with an edge, what happens if you go to the edge
and...." The ideas of what might be an edge may differ between models,
so you need to know what edge you are talking about. The colliding
universe model you mention sounds like the colliding brane models that
string theorists go on about. You need to specify which model you are
using exactly - 11 dimesnional string? Euclidean Universe? Which
dimensions are you approaching the edge along? One of the curled up
ones? The definition of edge may vary so much between models that you
need to get specific.

... I had been reading some "metaphysics" on
the nature of space and time.

Which metaphysic, how did this edge thing come up specifically?


.

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