The Arrow of Time

Published on by Catherine Toulsaly

What I see is four temporal dimensions: that which is, that which has passed, that which will be, and that which is always in the state of becoming. The first three are subjective. The latter is timelessness.


This past October, I mentioned that I would read Julian Barbour’s latest work. Lee Smolin is quoted to have said that it is simply the most important book he has read on cosmology in several years. What I appreciate in anyone’s writing — and I am only at the beginning of it — is the wealth and the extent of information that creates a sense of harmony. Barbour reminds us that Sir Arthur Stanley Eddington, known for his insightful description of individuals as four-dimensional objects of greatly elongated form with “considerable extension in time and insignificant extension in space,” coined the expression ‘arrow of time.’ At this juncture, I feel the need to write another series of transitional thoughts triggered by the start of Barbour’s essential work. They will help, I hope, with reorganizing concepts and ideas in my head. Needless to say that I will devote the next few posts to it. 


My previous article on Neptune brought me back to the utmost importance of the act of experiencing. Barbour lost his wife and daughter in the midst of writing his latest book on time. I can’t imagine that those tragic events did not mold his personal view of both worlds, the physical and the experiential. It is not that we need to paint the Universe with one brush instead of the other. We need both for the picture to be whole and complete. We feel so powerless as we experience the passage of time on a one-way ticket to a point of no return, whether that be nothingness or whatever we call the other side. The bond between Consciousness and the Physical Universe is, I feel, the most important subject within the mystery of time.


The signs of age are on the moon. It seems pitted, torn, and rent by the past action of long-dead fires, till its surface is like a piece of porous cinder of a planet, which rolls through the void like a ruin of what has been...

S.P. Langley, The Planets and the Moon

How the “arrow of time gets into things so profoundly” is as much a scientific puzzle as it is a philosophical enigma. Scientists struggle to reconcile symmetric laws with irreversible series of events that produce asymmetric results. Janus point  — that is the title of Barbour’s book — refers to the Big Bang “on either side of which the universe’s size increases.” Barbour seems to point to a process that happens simultaneously. Time no longer has one direction, but instead has two “from a common past at the Janus point to two futures in the two directions away from it.”The laws of Nature, writes Vlatko Vedral, are information about information, and outside of it, there is darkness. In a way, Barbour is investigating what ‘darkness’ may be. The reason why it feels like time is unidirectional is the seemingly infinite length of the arrow we stand on, which left us unable to fathom what the other side looks like. 


Barbour introduces an entropy-like quantity called entaxy that reflects the growth of complexity. The expansion of the Universe seems concomitant with the increase of its complexity. The thing with complexity is that it lacks uniformity across the Universe. From our limited observational capabilities, life as we know it is far more likely to get stuck at the bacterial level of complexity, asserts Nick Lane. We could allow our poetic selves to compare complexity-based systems such as a comet, a planet, or a star with Earth-based biological organisms, but that would not be the same. Complexity is darkness.


The planets must find their way through the void like the birds through the air.

Johannes Kepler

Reading gives me a chance to look through an optical prism from a different angle, with each time a new sense of wonder. Astronomers, writes Barbour, “do not see the Universe expanding; they see it changing its shape and from that deduce its expansion.” It reminds me of what Sharon Glotzer said, that there’s “something much more  fundamental to understand about the organization of matter, and by focusing on shape and entropy, we’re getting to the core of that.”Since entropy is, along with agency, one of the most difficult terms to understand, I’d like to review what ‘entropy’ means.  As time emerges from timelessness at the Big Bang and every time a particle/antiparticle pair is created or a new life begins, writes Kerri Welch, gravity emerges from a microscopic description “that doesn’t know about its existence,” adds Erik Verlinde so eloquently. The link between the Universe without gravity and the Universe with gravity is information  “measured in terms of entropy.” The expansion of the Universe reveals three intertwined fundamentals: gravity, information, and entropy in a process that has allowed the synchronic conversion of information into energy. 

I have intentionally formed the word entropy so as to be as similar as possible to the word energy; for the two magnitudes to be denoted by these words are so nearly allied in their physical significance that a certain similarity in designation appears to be desirable.

Rudolf Claudius, quotation from Janus Point, p.40



On the one hand, if entropy is a transformation value, shouldn’t it imply a primary focus on processes rather than on entities? Flows within one flow are processes occurring in the phenomenological realm of the Universe from one given time to the next. In the discussion on content and process, the avant-gardist Carlo Rovelli seems to be instinctively aware that there is neither space nor time, only processes that transform physical quantities. If entropy is indeed so abstract and difficult to visualize, it may be because, in the organized manifestation of the life of feelings, there is not just a difference of form but also content. We can think of the state of a system in the past as a 'preparation' and the future as the outcome, hoping to predict what ‘darkness’ or ’complexity’ is. On the other hand, if entropy is regarded as a probability of particle arrangement, it relates to a state of arrangement and particle movement and, in that sense, reminds me of what agency means, that is the setting of physical associations and the implied ability to make choices from one given time to the next.


With that being said, entaxy refers to the growth of complexity in the Universe that includes “the formation of previously nonexistent subsystems that become effectively self-confined,” writes Barbour. Even those subsystems appear to form in the two directions simultaneously. Barbour not only follows Ludwig Wittgenstein’s footsteps for whom the “sense” of the Universe lies outside the reality of the one coherent and public Universe where “everything is as it is and happens as it does happen.” As he zooms out of the Universe and surveys it from a higher vantage point,  what he has done is following the footprints of time. Events still occur within some form or another of space or/and time. It appears to differ from what Stuart Kauffman defines as res potentia that is before the Big Bang outside of any space but inside of time. 


Could an observer, convinced that the “sense” of the Universe must lie beyond, crawl outside and come back with the tale of the zygote constrained within the walls of a transparent membrane? If space-time is the record of physical reality, it is only one aspect of reality in the infinite game of space, time, and gravity.

The Process of Becoming

Never mind Rovelli and others’ idealism. Reason had become our chief instinct and caused us to act as transcendental correlationists for whom what exists outside the correlation is nothing but indeterminacy, as Alexander Wilson noted. Blurred vision, when faced with the absence of spacetime, explains our failure to distinguish not just what is unknown but what is unimaginable. If time existed on the other side of a cosmological singularity, no matter which fundamentals of reality take part in the circle of concepts and whether some are co-emergent,  it would bring me to the same conclusion of my first transitional thoughts that time comes first. Timelessness hosts the passage of time. From a point in the past — a pre-big-bang phase — remnants of a black hole gave birth to a primordial white hole bursting at once in a bouncing scenario.


Human consciousness, when it stands on the edge staring into oblivion, still can’t quite conceive any notion beyond spacetime. If neither space nor time exists, then can our experiential selves be the only ones to know? I remain cautious, once again, keeping in mind that I ought to go deeper. Barbour’s book provides me with the opportunity to do so. I’ll see what his take is on matters such as white holes crossing over through spacetime or from one universe to the next, wormhole structure between a black hole and a white hole, and the role of dark matter in the Early Universe.  


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