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

[Stephen Horne]

On 2 Nov 2003 10:16:20 -0800, mis6 at pitt.edu (Michele Simionato) wrote:

>Stephen Horne <steve at ninereeds.fsnet.co.uk> wrote in message news:<b1d9qvogqc424j0rkr00kq0lk4hdlj29id at 4ax.com>...
>> OK - but if you are describing superfluidity as a single macroscopic
>> effect then you must describe it within a macroscopic framework. At
>> which point it has nothing to do with quantum effects because it isn't
>> within a quantum framework - it is just that the macroscopic
>> phenomenon called electricity (distinct from electrons moving en
>> masse) is not subject to the macroscopic phenomenon called resistance
>> (distinct from energy loss through the electomagnetic interactions
>> between electrons and atoms en masse) when the macroscopic phenomenon
>> called temperature (distinct from the kinetic energy of atoms en
>> masse) is sufficiently low.
>> 
>> There is nothing wrong with this per se - it is the limit of most
>> peoples (mine included) understanding of superconductivity - but it
>> has nothing to do with the framework of quantum mechanics.
>> 
>
>I am sure I am misreading you again, but the equation is not
>microscopic=quantum, macroscopic=classical. It can be very
>well quantum=macroscopic. For instance, there is no classical
>theory able to describe superfluidity, it must be quantum.
>If I am misreading you again, let's say that I am doing this
>remark for the other readers here ;)
>
>                 Michele

But within a framework you don't explain the effects described in that
framework - at best you quantify them. e.g. Newton did not give an
explanation for how gravity works - he just quantified it. If you want
to explain the classical concept of gravity, you need to look at some
other model that predicts it - e.g. gravity is created by gravitons
(an old quantum theory which IIRC has been abandoned) or gravity is
space-time curvature (a relativistic theory).

If you are describing superconductivity as a single effect (rather
than explaining it in terms of quantum effects working en masse) then
it is certainly a macroscopic effect (you can look at it), but
basically in that framework you are saying 'this is how it is, get
used to it'.

This is the same as giving a formula for electrical resistance rather
than explaining it in terms of the many interactions of electrons and
atoms within the wire. The formula belongs in the macroscopic
framework. I'm not saying a single quantum effect cannot be
macroscopic, but superconductivity is explained by the way that
electrons interact with atoms at low temperature - it is only a single
effect in itself in a macroscopic framework where you say "here is how
it is, get used to it".

If you are explaining how superconductivity arises, then it arises out
of microscopic quantum effects acting en masse.

However, now that I think harder, I just countered myself in a way.
There isn't just one QM framework exactly - there are layers within
that too (e.g. quarks relative to protons) so a macroscopic quantum
effect can be explained in terms of a microscopic quantum effect and
so on. It really depends on whether you call superconductivity a
quantum effect even though you aren't looking at simple interactions
between quanta.

Maybe my definition of 'quantum' is odd, in other words, taking a
principle too strictly and ignoring normal conventions.


-- 
Steve Horne

steve at ninereeds dot fsnet dot co dot uk