Friday, April 11, 2014

A multiverse suggestion from the 13th century?

by Salman Hameed

It is generally a good practice to be highly skeptical of people claiming to find ideas from modern science in literature written centuries or millennia before. However, here is an interesting inter-The Ordered Universe Project, that deserves more attention. It deals with a 13th century treatise, De Luce (On Light), by English scholar Robert Grosseteste (1170-1253 CE). What is interesting in Grosseteste's work is his idea that the same physical laws govern both the Earth and the heavens - something that went against the accepted wisdom of the time. Here is a bit from Nature:
disciplinary project,
De Luce (On Light), written in 1225 in Latin and dense with mathematical thinking, explores the nature of matter and the cosmos. Four centuries before Isaac Newton proposed gravity and seven centuries before the Big Bang theory, Grosseteste describes the birth of the Universe in an explosion and the crystallization of matter to form stars and planets in a set of nested spheres around Earth. 
To our knowledge, De Luce is the first attempt to describe the heavens and Earth using a single set of physical laws. Implying, probably unrealized by its author, a family of ordered universes in an ocean of disordered ones, the physics resembles the modern 'multiverse' concept. 
Grosseteste's treatise was translated and interpreted by us as part of an interdisciplinary
project led by Durham University, UK, that includes Latinists, philologists, medieval historians, physicists and cosmologists (see ordered-universe.com). Our experience shows how science and humanities scholars working together can gain fresh perspectives in both fields. And Grosseteste's thesis demonstrates how advanced natural philosophy was in the thirteenth century — it was no dark age.

By the late twelfth century, Aristotle's observation-oriented science had burst afresh onto the European scene, transmitted in a long series of cross-cultural translations from Greek to Arabic to Latin. Great questions arose in the minds of scholars such as Grosseteste, Averroes (in Cordoba) and Gerard of Cremona (in Toledo). What is colour? What is light? How does the rainbow appear? How was the cosmos formed? We should not underestimate the imaginative work needed to conceive that these questions were, in principle, answerable. 
Grosseteste (c.1175–1253) rose from obscure Anglo–Norman origins to become a respected theologian and Bishop of Lincoln. He was one of the first in northern Europe to read the newly translated scientific works of Aristotle, attempting to take forward the big questions of what we can know about the natural world (ontology) and how we know it (epistemology). The late thirteenth-century philosopher Roger Bacon called him “the greatest mathematician” of his time. Grosseteste's work on optical physics influenced mathematicians and natural philosophers for generations, notably in Oxford during the fourteenth century and in Prague during the fifteenth.
The authors provide several examples of Grosseteste's work dealing with science. However, the most interesting one deals with something that looks like an idea for the Big Bang. But I think here we also have to be very careful. Remember, that Grosseteste is working in a geocentric universe - and a universe that is dominated by planets that are visible to the naked eye (separate spheres for Mercury, Venus, Mars, Jupiter, Saturn, and yes, the Moon and the Sun). Here is the bit about the Big Bang:
The third remarkable ingredient of De Luce to modern eyes is its universal canvas: it suggests that the same physics of light and matter that explains the solidity of ordinary objects can be applied to the cosmos as a whole. An initial explosion of a primordial sort of light, lux, according to Grosseteste, expands the Universe into an enormous sphere, thinning matter as it goes. This sounds, to a twenty-first-century reader, like the Big Bang. 
Then Grosseteste makes an assumption: matter possesses a minimum density at which it becomes 'perfected' into a sort of crystalline form. Today, we would call this a phase transition. The perfection occurs first at the thinnest outer edge of the cosmos, which crystallizes into the outermost sphere of the medieval cosmos. This perfect matter radiates inward another sort of light, lumen, which is able to push matter by its radiative force, piling it up in front and rarefying it behind. An analogous process in today's physics is the inward propagation of shock waves in a supernova explosion. 
Like a sonata returning to its theme, that finite ratio of infinite sums reappears, this time as a 'quantization condition' — a rule that permits only discrete solutions such as the energy levels in atoms — that limits matter to a finite number of spheres. Grosseteste needed to account for nine perfect spheres in the medieval geocentric cosmos: the 'firmament', the fixed stars, Saturn, Jupiter, Mars, the Sun, Venus, Mercury and the Moon. By requiring that the density is doubled in the second sphere and tripled in the third, and so on, a nested set of spheres results. 
In an impressive final stroke of unification, he postulates that towards the centre of the cosmos, the remaining unperfected matter becomes so dense and the inwardly radiating lumen so weak, that no further perfection transitions are possible. He thus accounts for the Aristotelian distinction between the perfect heavens and the imperfect Earth and atmosphere. 
To our knowledge, De Luce is the first worked example showing that a single set of physical laws might account for the very different structures of the heavens and Earth, hundreds of years before Newton's 1687 appeal to gravity to unite the falling of objects on Earth with the orbiting of the Moon. Our translation has also cleared up a misconception in some previous studies that the light in Grosseteste's treatise travelled both inwards and outwards.
This is an interesting work. You can read the Nature article here (you may need subscription to access it). 

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