Geoscience Reference
In-Depth Information
In the extreme case of a planetary system, the limit again becomes
pertinent (the summit of the atmosphere, if there is one, or the soil
surface, or the sea surface), since there is a great contrast between a
medium where, under the effect of gravitational attraction, the density
of the matter is high (the interior of the system, atmosphere included)
and a medium where the density of matter is close to zero (the planet's
exterior, interplanetary space). However, unlike living beings, such a
system is not “reproducible” in a biological sense; in other words, it has
no equivalents. Despite that, it can, like living beings, have global
characteristics essentially invisible to the non-scientific observer,
notably in terms of self-organization, regulation and adaptive evolution.
1.1.2.
One system is necessarily built into another
A multicellular organism is, as the name suggests, an organized
living being; in other words, it is composed of organs that interact
with each other in that they maintain the existence of the organism as
a whole. But the organisms themselves are composed of specialized
(somatic) cells that have interactions between them. It is therefore
evident that the arbitrary limit of the internal components of a system,
which amount to subsystems but not necessarily to organs, depends
directly on its external definition, that is to say on the identity that we
attribute to it.
The natural systems are therefore like Russian dolls on the small
just as on the large scale, the absolute theoretical limits only being
imposed on a small scale by: the indivisibility and the indetermination
of the most fundamental quantum particles (e.g. quarks), the
indivisibility of the information
(quantum information, Boltzmann
constant
h
) or
the indivisibility of time
(“Planck” time = 10
-43
s). On a
large scale, they are imposed by the spatio-temporal frontiers of the
observable universe, in the case of the Big Bang, 13.7 billion years ago,
and the finite speed of light,
places or events that have occurred at a
great distance from us. However, there is a theoretical intermediate
limit between the ensemble of “macroscopic” components, dominated
by interactions that can be described in a
mechanistic way (contacts, flux of matter and energy), and that of
“microscopic” components, dominated by
interactions that can only
