The Publisher Says: In a universe filled by chaos and disorder, one physicist makes the radical argument that the growth of order drives the passage of time — and shapes the destiny of the universe.

Time is among the universe's greatest mysteries. Why, when most laws of physics allow for it to flow forward and backward, does it only go forward? Physicists have long appealed to the second law of thermodynamics, held to predict the increase of disorder in the universe, to explain this.

In The Janus Point, physicist Julian Barbour argues that the second law has been misapplied and that the growth of order determines how we experience time. In his view, the big bang becomes the "Janus point," a moment of minimal order from which time could flow, and order increase, in two directions. The Janus Point has remarkable implications: while most physicists predict that the universe will become mired in disorder, Barbour sees the possibility that order — the stuff of life — can grow without bound.

A major new work of physics, The Janus Point will transform our understanding of the nature of existence.

I RECEIVED A DRC FROM THE PUBLISHER VIA NETGALLEY. THANK YOU.

My Review: On the Solstice, I think a lot about time. Why time's arrow only points in one direction, for example. I am always bothered by the implication inherent in the laws of physics that we presently understand that this is an observational artifact, not part of the structure of physics.

While I sit and ponder the strange dichotomies between what we observe and what theory tells us is possible, Author Barbour sets himself the task of learning the why, and questioning the how, of all the factors in physics that determine this issue's boundaries. That is an immense task.

It is also one well beyond most people's educational, vocational, and experiential capacities. The author isn't writing an academic paper in this book. He is, however, presupposing a lot of knowledge on the reader's part...if you don't know what a Boltzmann brain is, for example, this book will be lost on you...and even for those with the requisite grounding in at least the people who created the outlines of the Standard Model of particle physics, the need for frequent research breaks, aka "fallings down the many rabbit holes", is ever-present.

Very much not a Wikipedia-level treatment of an immensely important topic being argued, studied, researched, and pondered by some of the best-furnished minds in the field of physics today; yet it does not repel boarders with its case-shot loaded cannons of erudition. Author Barbour is quippy and quotable. The problem is quoting him won't help. This is someone with a very broad grasp of physics, history, cultural anthropology, etc. He lays out arguments that I suspect I only dimly grasp for his new model of endlessly repeatable order, ie creation of matter instead of its inevitable and complete decay, grounded in all the currents of thought there are.

Not, as you'd expect, a mere bagatelle to be consumed of an evening. Took me two years to read it, and I regret not a page or a minute of it. I was rewarded with a greatly expanded idea of what the science of physics is reaching for in its quest for a unified theory.

At this #Booksgiving moment, self-gifting this immensely challenging and deeply absorbing book is a great way to invest in your brain's expansion in entirely new ways and directions. It will be a Project. It is also well worth your eyeblinks. ( )

Viewed as a cosmology book, this volume will remind some readers of Sean Carroll's _From Eternity to Here_ (2010) and its idea of different baby universes having different time arrows. But Barbour proffers much, much else, including the bringing in of advanced concepts like shape dynamics and a radical rethinking of thermodynamics. Saying that he "aims to overturn the doctrine that it is entropic disorder on a cosmic scale that puts the direction into time," he introduces a pure-number quantity called "entaxy" that is entropy-like but, for the universe as a whole, tends to *decrease* and allows for "the growth of structure and complexity." Many of the details remained beyond my comprehension, partly because I was reading a defective copy of an ebook version.

Time? There is only the ever present now - the past no longer “is” and the future not yet “is”.

As it so transpires it turns out that that which we consider to be the passage of the river of time is nothing other than the persistence of our own personal memories of events that we each have already experienced and which now exist only in our memory of them, while the future is an imaginative projection of past memories into what we expect to experience in the next series of ‘nows’ as we step, one by one, into them. A corrected understanding of everything here inside our universe - time, space, matter, energy, entropy, motion, inertia, sentience, knowledge and knowing (to less than exhaust the list) not only clearly debunks the Einsteinian understanding thereof, but even, gulp, dethrones the Newtonian one also, as with this corrected understanding it becomes eminently possible to recognise that matter - that all material being, both animate and inanimate alike - is a fully self-organising phenomenon; is a fully self-powered, self-moving, self-directed, self-timed, sentient/self-aware phenomenon in all of its many and various instantiations. Among other corrected understandings, it shows that we live in a panpsychic universe. Because no information exists outside our universe - presumably that sphere or realm where the creator/sustainer of it all resides (if there is one), along with its reasons for so doing (if it has any), sadly there is no way we can apprise ourselves of any of these ‘externalities’. But with ‘information’s’ corrected identity factored into the reality equation it becomes amply apparent that we no longer need to grapple with either a Newton or Einstein perspective. Indeed, ‘information’ aside, there is now essentially ample and fully conclusive hard evidence that our universe is a plasmatic one, one in which electromagnetic phenomena shape everything, and which phenomena is roughly forty orders of magnitude stronger than gravity, making the latter almost totally impotent, almost totally irrelevant, in regard to any good and proper understanding of ourselves and the demonstrably plasmatic universe in which we live, and move and have our being. General Relativity is derived from looking at the very largest of scales. Quantum Mechanics is derived from looking at the tiniest of scales, and its approach is fundamentally different from GR, being 'probabilistic' in nature (which inherently necessitates time). Both of them extrapolating from their point of view - towards the other end. Is it surprising that the 'two ends of the tunnel' don't quite meet up? ... Not really :)

Nice try Julian, but around forty orders of magnitude off the mark. ( )