The British physicist Julian Barbour is one of those admirable people who, having gained his PhD, realised that concentration on research and scholarship is incompatible with working in the modern university, and has had a very successful career as an independent researcher in the foundations of physics.
Most notably, starting from the observation that we experience time flowing in a single direction while such a unique direction of time does not feature in any of the fundamental theories of physics, he has formulated a view of the universe without time as fundamental feature. His published papers are rather hard going for those without a background in physics and mathematics, but his two books for the general reader go into a good level of detail. The end of time: the next revolution in physics (1999) sets out his idea of a timeless universe, while The Janus point: a new theory of time (2020) presents the idea that the appearance of a flow of time is associated with the expansion of the universe and by growth of complexity within it.
Barbour’s ‘timelessness’ viewpoint has not by any means met with general acceptance in the physics community. Typical is the perspective expressed by Sean Carroll in a blog post, ‘Timelessness’, from 2009: “The problem is not that I disagree with the timelessness crowd, it’s that I don’t see the point. I am not motivated to make the effort to carefully read what they are writing, because I am very unclear about what is to be gained by doing so. If anyone could spell out straightforwardly what I might be able to understand by thinking of the world in the language of timelessness, I’d be very happy to re-orient my attitude and take these works seriously.”
To my mind, some of Barbour’s theories, developed over several decades, have a resonance with the idea that information and documents, understood very broadly, are fundamental features of the universe, and it is this, for me, which makes his ideas intriguing and worth attention.
Newton regarded the flow of time as a fundamental feature of the word: “Absolute, true, and mathematical time, of itself, and from its own nature, flows equably”. Einstein’s theories of relativity, and quantum theory, has qualified this simple formulation, but without removing the fundamentality of time. Barbour replaces this with the fundamental idea of the “instant”, a single moment capturing the whole configuration of the universe. The history of the universe (or rather multiverse, since Barbour’s theory is quantum in nature) comprises a collection of such instants. The reason we experience a flow of time is that each instant contains records of some events, which we call the past. There is, in fact, no passage of time, only a series of instants, but each instant contains records, including human memories, which give the impression that time is passing. The direction of time is fixed by the growth of structure, information, and records. In The end of time, Barbour writes “Records, or apparent records, play a vital role in my idea that time is an illusion… My position is that the things we call records are real enough, and so is their structure. They are the genuine cause of our belief in time”.
A full account of the creation of records in this sense is given in chapters 20 and 21 of The end of time. These are typically things like tracks of subatomic particles in cloud chambers; what we would normally regard as ‘raw data’. But they lead naturally to a broader account of records “I use records primarily in the sense of, for example, fossils which occur naturally and are interpreted by us as relics of things that actually existed. Less directly, all geological formations, rock strata in particular, are now invariably interpreted by geologists as constituting a record (to be interpreted) of past geological processes. Finally, there are records that people create deliberately: doctors notes, minutes of committee meetings, astronomical observations, photographs, descriptions of the initial and final conditions of controlled experiments and so on. All such things, and many more, I call records.” (The end of time, pp30-31). Remarkably similar to the idea of documents, as analysed in the document theory of Otlet and Briet, set out in Niels Lund’s recent book. And indeed Barbour, in The Janus point, makes the connection explicit: “Bodley in Oxford is one of the world’s great libraries, but we have been born into the ultimate library. It’s all around us. It’s the universe.” Perhaps just a coincidence of terminology, but worth considering I think in any consideration of ideas of information and documents in different realms.
Barbour’s theory also deals with another troubling problem; the conventional view that the passage of time is equated to the growth of entropy. This envisages the universe beginning in a state of uniquely low entropy, and hence higher order, and the steady growth of entropy through time; for a good survey of this, see Lena Zuchowski’s From randomness and entropy to the arrow of time. This view seems strangely at odds with our experience of the growth of order and complex structures as time passes. There is a complicated, and not well understood, relation between information and entropy, and equally between information and complexity.
Barbour, in The Janus point, finds it a “flagrant contradiction” that the current consensus is that for some reason the universe began with a very low entropy and high order that has been undergoing degradation according to the second law of thermodynamics “yet all around us in the universe we see a wonderful growth of structure and order” …”. There are records – for example, documents, fossils, and stars (considered as “fossils” of stellar evolution), which have remarkable mutual consistency, and give evidence for quite the opposite of what is claimed: that the history of the universe is not one of increasing disorder but rather of the growth of structure. “The cosmos begins with near perfect uniformity and evolves to increasingly rich complexity.”
He introduces the concept of entaxy, analogous to entropy, but suitable for an unbounded universe, whereas entropy is always defined for bounded systems “in a box”. In contrast to ordinary entropy, entaxy decreases with time, rather than increasing; what increases is complexity rather than disorder. With complexity, structures are created which become effectively self-contained, and it is within these that conventional entropy increases. Barbour suggests that complexity, formally defined, is more important than entaxy; it reflects what we see in the universe, and makes it possible to define entaxy. A detailed description is given in The Janus point, and, with more mathematics, in a paper in ArXiv and a video lecture.
Whether or not Barbour’s ideas enter into the mainstream of physical theory, they offer much food for thought for anyone interested in the place and significance of information, records and documents in the physical world.
The Occasional Informationist 