Theoretical and epistemological approaches

 

22-24 March 2010, Paris

CNRS Auditorium
3, rue Michel Ange
Paris 75016

Our understanding of the large scale structure of the cosmos has achieved a spectacular progress during the last 10 years; cosmology has left the realm of philosophical speculation to become high precision science. Furthermore, since the Universe evolved from a state of extremely high energy and density one can use the knowledge obtained in the study of the elementary particles to approach the origin of the Universe.
 

According to this view, as one probes smaller and smaller distance scales, or equivalently higher energies, one discovers particles and interactions of higher symmetry. A different set of particles and interactions reveals itself at each scale, up to the highest energies where the unification of gravity and subatomic physics promises to derive particles, forces and even space-time properties from a minimal set of fundamental entities, as it is the case, for example, in the recently developed super-string theories.
 

Conversely, as the Universe “cools down” from its original high temperature state a series of successive phase transitions break the initial symmetries to form our present-day asymmetric but sufficiently eventful cosmic structures. An intensive experimental program tries to trace these transitions and the particle content that they correspond, using a series of different instruments from accelerators to gravitational wave antennas. Furthermore, since the vacuum contains virtually the higher energy physics, one can study the latter through “radiative” precision corrections to low-energy observables.

Concurrently, a philosophical point of view has gained strength recently, wondering whether one should make a distinction between the origin of things and the origin of their organisation. This standpoint criticises what it sees as the will to designate a fundamental entity as ultimate source of all things. It points to the fact that the question of the origin of laws and the organisation of matter in large scales has achieved also considerable progress through the refinement of the concepts of emergence and complexity. The idea of “protection” of the order of the emergent level from the details of the process of the level below, coming from condensed matter physics, permitted the understanding of several laws hitherto unexplained.
 

In this view, there is a symmetry between emergent levels: one should not distinguish between a “substratum” scale equipped with “fundamental properties” and a higher scale whose laws can be reduced to a variety of dynamical relationships between the “fundamental” entities of the scale below. The “emergentist” school puts thus in question the distinction between levels and would like to generalize the relational or organisational model to all scales, including the scale of “elementary” processes. The idea of an ultimate foundation of things is also put in question. If there is no difference between fundamental and emergent levels, the first should not receive any theoretical priority.
 

To these arguments, those accused of being “fundamentalists” answer that far from giving priority to the “fundamental” level they simply believe that different processes should be examined at their pertinent scale and that new mathematical laws can be explored at each scale.
 

This workshop has the ambition to trigger a high level discussion of the above views; they do correspond after all to the two meanings of “arche”, the Greek word for origin, both foundation and organisation principle.