AI and cognitive psychology rant (getting more and more OT - tell me if I should shut up)

[Michele Simionato]

Stephen Horne <steve at ninereeds.fsnet.co.uk> wrote in message news:<1589qvcdv9bni5fr8opactkgj9n5hecpj7 at 4ax.com>...
> And yes, even classical mechanics could not have been our first model
> for simple commonsense reasons. How often, for instance, did ancient
> Greeks get to observe objects moving through a frictionless
> environment?

It is a bit strange that Ancient Greeks did not discover classical
mechanics. Actually, entire books have been written on the subject,
trying to elucidate the economical and psychological mechanisms behind
this failure of the genial Greeks. 

> I find the 'infinite' theory dubious - if the expansion rate has
> remained finite since the big bang, then how can space have grown to
> become infinite? The only way I can understand it is if space was
> always infinite. That wouldn't necessarily mean it can't 'expand',
> just as it isn't necessarily impossible to multiply infinity by two.

You are perfectly right. 

Notice that the expansion should not be taken to its
extreme consequences: at a certain scale the Universe enters in its
quantum gravity regime and we don't know nothing about its behavior
then. There are string-inspired models in which the so called Big Bang
does not exist and never happened. Many feel this perspective more
appealing.

> I guess 'expansion' relating to the universe is a metaphor too, really
> - after all, the universe isn't an object within some other space. The
> 'expansion' is really just rewriting of the scale factors on the
> dimension axes of the universe, I suppose. 

You are right.

> That being why the speed of
> light isn't a problem in inflation - nothing is actually moving faster
> than the speed of light, even though the distances between things is
> expanding faster than the speed of light.

That's pretty tricky. The maximum velocity for transmission of information
is always the speed of light, but depending on how you define distances 
(which is tricky) you can get (apparently) speeds higher than that. I
find impossible to get an intuitive picture of how velocity compose
in the early Universe, even if I understand well the mathematics
involved (nothing more complicate than solving a differential equation
for the geodetic lines). It's the interpretation the real issue, as
always in modern Physics ;)

Also, a thing that confused me was Hubble law: if the speed of galaxies
increases with distance, one would naively think that at a certain moment 
it will get higher than c. The solution of the paradox is that the linear 
Hubble's law only works locally: there are corrections for far away 
galaxies, so the maximum speed is always c. 

Interested people should look at Weinberg's book on General Relativity,
the chapter on cosmological distances: however, be warned that it is
non-trivial!

> Hmmm - I wonder if 'expansion' or 'scale' is a continuous value in
> space-time, like curvature? Well, I guess it must be really - just
> write the model in those terms and hey presto - but what I mean, I
> guess, is "is there a function that can define that 'scale' in terms
> of local physics to explain things we don't currently have an
> explanation for?".

I do not understand what you are trying to say here.

> And as has already stated, there are other explanations
> of waveform collapse that don't require consciousness to take a
> special role. Explanations that make more sense, as the observer never
> had any control over how the waveform collapses - it is a mechanical
> process that follows clearly defined non-mystical rules.

Agreed.

                  Michele Simionato