Luc Brisson

> Babelio : https://www.babelio.com/livres/Brisson-Inventer-lunivers-Le-Probleme-de-la-conna...
> Érudit (Philosophiques, 19(1), 150–155) : https://doi.org/10.7202/027183ar

> Touwaide Alain. Luc Brisson et Walter Meyerstein, Inventer l'univers. Le problème de la connaissance et les modèles cosmologiques.
In: L'antiquité classique, Tome 62, 1993. p. 410. … ; (en ligne),
URL : https://www.persee.fr/doc/antiq_0770-2817_1993_num_62_1_1176_t1_0410_0000_1

> INVENTER L'UNIVERS, Le problème de la connaissance et les modèles cosmologiques, de Luc Brisson & F. Walter Meyerstein. — Luc Brisson, chercheur au CNRS, est l’auteur d’un livre sur le Timée de Platon : Le Même et l’Autre dans la structure ontologique du Timée de Platon; F. Walter Meyerstein est philosophe des sciences. Leur ouvrage, d’une grande originalité, a le mérite d’oser mettre en parallèle la conception du monde de Platon exposée dans le Timée et la version cosmologique, majoritairement acceptée, du Big Bang standard. Les deux modèles, celui de Platon et celui de cette science de pointe qu’est la cosmologie, s’élaborent tous deux sur une suite bien précise de principes mathématiques. Selon les auteurs, ces principes sont des axiomes qui par définition sont a priori et arbitraires, donc “inventés”. Mais peut-on ramener à une axiomatique, au sens moderne du terme, autant les idées du Big Bang standard que celles du Timée de Platon ? Car enfin, si un grand nombre d’observations astrophysiques corroborent le modèle standard du Big Bang élaboré aux fins d’en fournir une explication cohérente ; nous restons là en plein mystère lorsqu’il s’agit de s’expliquer comment et pourquoi Platon - et tous les néoplatoniciens après lui - a élaboré un tel modèle. Pas sur des observations que nous appellerions “objectives”.., c’est certain ! Alors : sur quelque naïve croyance…?! C’est ce que l’on ne peut plus, honnêtement, sous-entendre aujourd’hui. Et la question doit être posée avec insistance : sur quel type d’intuition ou d’inspiration fut élaborée la cosmologie platonicienne ?… C’est ce type d’interrogation qui donne, à 3e millénaire, son orientation si particulière : la rencontre science et tradition. Et cet ouvrage judicieux, s’il ne pose ni ne répond à cette question, lui permet de se formuler avec plus d’acuité et de nombreux éléments de synthèse. Ed. Les Belles Lettres - Collection « L'âne d'or », 1991 - 205 p.
—3e millénaire, (22), Hiver 1991… (altro)

File under Epistemology, Philosophy of Science, and Plato Gets There First.

Inventing the Universe is an impressive and illuminating examination of two fundamental cosmological models, Plato’s Timaeus and the contemporary standard Big Bang model. After tracing the construction of the two models and noting the similarities, appraising the gap between perception and explanation then firing off some fairly high-powered mathematics and deploying the Algorithmic Theory of Information, Brisson and Meyerstein conclude that "there is no logical relationship between the sensible perception of the world and a formalized system of axioms called ‘scientific explanation.’ The kind of knowledge called ‘scientific’ ultimately rests on a set of irreducible and indemonstrable formulas—pure inventions of the human mind." This is not an original conclusion, but it is another good reminder of the boundaries of knowledge, even (and especially) the scientific kind.

As Brisson and Meyerstein note, no scientific knowledge is possible without some formal axiomatic framework, a set of propositions that are assumed without proof for the sake of studying the consequences that follow from it. The real surprise is how the list of axioms proposed by Plato in the Timaeus in the 4th c. BCE and the list of axioms underlying the Big Bang model rely on the same abstract concepts: notions of order, harmony, symmetry, measurement, stability, invariance, eternity and the universality of the laws of nature. Remarkably, the axioms that constituted Plato’s theory of matter read like a neat summary of modern particle physics: the entire universe can be reduced to discrete, elementary components; these components are simple, indestructible, and infinitely small; all observable phenomena in the universe can be reduced to interactions between these elementary components.

Plato assumed that the universe was characterized by abstract properties which could be mathematically formulated. (This is why a modern physicist like Roger Penrose can call himself a “Platonist”). Plato also knew that a mathematical model devised by common mortals could never be more than a plausible copy of true reality (he called his model in Timaeus “a likely story”). Modern science shares this predicament, write Brisson and Meyerstein: "every theory is at best a provisional explanation of some phenomenon, which remains open-ended, since a theory can only resist falsification, but can never be verified."

Einstein proposed the first modern model of the universe, based on a system of fundamental laws formulated in mathematical equations relating the matter and energy of the universe to the cosmic geometry. The geometrical approach (having evolved more complexity since Plato’s time) inevitably breaks down, however, as some parameters approach infinity at particular points in space-time. These points, called ‘singularities,’ are not directly observable, and no known physical theory can describe what happens at the singularity itself. (The most famous Singularity is the Big Bang). Thus, according to Brisson and Meyerstein, the modern cosmological model, like Plato’s Timaeus, rests upon some rather bold axioms: the universe is assumed to be ‘simple’ (galaxies and clusters of galaxies, for instance, are considered to be point-like), and the mathematical laws that apply to physical phenomena are assumed to be valid “everywhere and everywhen” throughout the universe.

The mathematics behind the standard Big Bang model’s first nine axioms, summarized, read like this:

“The universe is modeled by a Hausdorff separable, C∞ four-dimensional manifold, connected and without boundary. Everywhere on this manifold, a Lorentz signature metric function can be defined.”

Whew. Surely the ideas contained in those two sentences are a monument to the creativity of the human mind. Inventing the Universe does an admirable job of tracing the process by which generations of mathematicians and physicists built on the initial insights of Einstein to arrive at such a conception.

It is amazing how much Einstein (and Plato before him) got right, without recourse to the technologies that scientists have today. Yet even with Hubble’s detection of the ‘red shift’ and observations of cosmic microwave radiation and the abundance of light elements in space, sense-perception data cannot lead to any intelligible explanation independent from a formalized axiomatic theory. Assumptions will be made. Any theoretical model derived from said axioms remains undecidable, according to Brisson and Meyerstein, because the mathematical laws underlying the model cannot be verified, since the differential equations by which they are expressed describe elementary interactions taking place in an infinitesimal region of space-time. Relying exclusively on observations, then, and taking for granted minimal assumptions, it remains impossible in principle to determine all features of the space-time structure of our light-cone (for instance, whether or not space-time is spherically symmetrical about our position)—not to mention what lies outside of the light-cone. The best we can come up with is ‘a likely story.’… (altro)