We do not think that Robert Grosseteste anticipated the modern notion of the Multiverse in his de Luce of c.1225
The reason for the short version is that I have learned that a good number of commentators on these pieces seem not to have read past their titles, let alone the actual research paper that the articles point to which in journal form in the Proceedings of the Royal Society is here and in green open access on the arXiv here.
So what do we say, and how do we say it?
While saying very clearly that Grosseteste is not doing ‘science’ as we define it now, I am equally deeply suspicious of ‘discontinuous’ theories of the history of science that suddenly have the fog being blown away around 1600. It just took much longer than that to work out what questions might be worth asking (and which of these are ready to yield fruit with the tools currently at hand), how we might find out some answers, whether mathematics had anything to do with nature at all, what might constitute a solved problem (I note that different sciences disagree on this one even today).
It’s also important to realise that the Ordered Universe collaboration runs two quite different activities that spring from its interdisciplinary collaboration around the reading of medieval manusscripts on natural philosophy:
(1) scientists work with humanities scholars on the 13C mss so that mathematical and physical aspects of the content receive more attention than is typically the case in commentaries – this has uncovered a number of previously unappreciated ideas such as Grosseteste’s 3-dimensional conceptual colour space (this is not a retro projection – he works through the combinatorics explicitly).
(2) we allow that interaction to inspire new calculations or investigations. That’s not ‘presentist’ either – science is allowed get its ideas from anywhere, and we don’t pretend that any of it was in the mind of our 13C author. The toy calculations of the medieval cosmos are an example of that.
But the point is that by doing (2), the whole group is forced into much closer examination of texts than before. So, for example, the idea that Grosseteste held, that the same underlying laws might lead through a dynamical process to the very different worlds above and below the sphere of the Moon (we would call it a broken symmetry), while obviously nonsense as an account of the actual world (we don’t live in a geocentric cosmos), is nevertheless a profound insight that resonates strongly with Newton’s anzatz that gravity might operate both on orbital motion in the heavens and on parabolic trajectories of falling objects on earth.
More is true however – we have found repeately that the second class of investigations, while differently-framed from the first, can nevertheless inform them. A goog example of how task (2) can inform task (1) is to be found in the interpretive work we have done on De Iride (on the rainbow). The application of modern optical, diffraction, atmospheric and colour perception theories together, show that the three aspects of rainbows that Grosseteste describes (refraction angle within a rainbow, different types of rainbow – by droplet size, different colours of solar illumination – by solar altitude) do indeed sweep out a sizeable region of our three-dimensional perceptual colour space. A real interpretive puzzle set by the de Colore is solved by employing modern science to the conjectures articulated in the de Iride.
The (medieval) cosmological calculations using our “mathematical translations” of Grosseteste’s de Luce are rather different in context. The 13th and 14th centuries had a theory of multiple universes, but not as a cosmological question; it is a useful parallel to draw on, but it seems easy to confuse people on this one. We do find that it is possible to compute quantitatively with the alternative physics in the treatise, and that this (with precise choice of parameters) can result in a 10-sphere universe. But the text itself is rock-solid that the actual universe does indeed conitain just 10 spheres (and Grosseteste calls on a strange Pythagorean numerology to ‘explain’ the number). The mathematical calculations actually refer to a small part of the text – the earlier sections are addressed at the extensive properties of solid matter, and the role of infinite generation of light in sustaining solidity. We will be taking a holistic look at the text when the project’s edition, translation and commentary is published.
Is Grosseteste doing science as we would define it today? No he is not. Is he making an important step on the critical path towards the assumptions and methodologies of the activity we now call science? Very much so. We might say that he is writing a vital chapter in the book whose chapter we are currently reading is called ‘science’. Does establishing this require the intensive engagement of the scientist-inheritors of that history of thought with the historians, philosophers and philologists who can unlock the language and context of these fascinating records of imaginative thought? We are finding that it does.