There’s a quiet revolution underway in theoretical physics. For as long as the discipline has existed, physicists have been reluctant to discuss consciousness, considering it a topic for quacks and charlatans. Indeed, the mere mention of the ‘c’ word could ruin careers.

That’s finally beginning to change thanks to a fundamentally new way of thinking about consciousness that is spreading like wildfire through the theoretical physics community. And while the problem of consciousness is far from being solved, it is finally being formulated mathematically as a set of problems that researchers can understand, explore and discuss.

Given that it is a phenomenon of information, a conscious system must be able to store in a memory and retrieve it efficiently.

It must also be able to to process this data, like a computer but one that is much more flexible and powerful than the silicon-based devices we are familiar with.

Tegmark borrows the term computronium to describe matter that can do this and cites other work showing that today’s computers underperform the theoretical limits of computing by some 38 orders of magnitude.

Clearly, there is so much room for improvement that allows for the performance of conscious systems.

Next, Tegmark discusses perceptronium, defined as the most general substance that feels subjectively self-aware. This substance should not only be able to store and process information but in a way that forms a unified, indivisible whole. That also requires a certain amount of independence in which the information dynamics is determined from within rather than externally.

Most scientists are confident that consciousness emerges from unconscious complexity. We have compelling reasons for believing this, because the only signs of consciousness we see in the universe are found in evolved organisms like ourselves. Nevertheless, this notion of emergence strikes me as nothing more than a restatement of a miracle. To say that consciousness emerged at some point in the evolution of life doesn’t give us an inkling of how it could emerge from unconscious processes, even in principle.

I believe that this notion of emergence is incomprehensible—rather like a naive conception of the big bang. The idea that everything (matter, space-time, their antecedent causes, and the very laws that govern their emergence) simply sprang into being out of nothing seems worse than a paradox.

To say “Everything came out of nothing” is to assert a brute fact that defies our most basic intuitions of cause and effect—a miracle, in other words.

Likewise, the idea that consciousness is identical to (or emerged from) unconscious physical events is, I would argue, impossible to properly conceive—which is to say that we can think we are thinking it, but we are mistaken. We can say the right words, of course—“consciousness emerges from unconscious information processing.” We can also say “Some squares are as round as circles” and “2 plus 2 equals 7.” But are we really thinking these things all the way through? I don’t think so.

Consciousness—the sheer fact that this universe is illuminated by sentience—is precisely what unconsciousness is not. And I believe that no description of unconscious complexity will fully account for it. It seems to me that just as “something” and “nothing,” however juxtaposed, can do no explanatory work, an analysis of purely physical processes will never yield a picture of consciousness. However, this is not to say that some other thesis about consciousness must be true. Consciousness may very well be the lawful product of unconscious information processing. But I don’t know what that sentence means—and I don’t think anyone else does either.

Hyl. I frankly own, Philonous, that it is in vain to longer. Colours, sounds, tastes, in a word all those termed secondary qualities, have certainly no existence without the mind. But by this acknowledgment I must not be supposed to derogate, the reality of Matter, or external objects; seeing it is no more than several philosophers maintain, who nevertheless are the farthest imaginable from denying Matter. For the clearer understanding of this, you must know sensible qualities are by philosophers divided into Primary and Secondary. The former are Extension, Figure, Solidity, Gravity, Motion, and Rest; and these they hold exist really in bodies. The latter are those above enumerated; or, briefly, all sensible qualities beside the Primary; which they assert are only so many sensations or ideas existing nowhere but in the mind. But all this, I doubt not, you are apprised of. For my part, I have been a long time sensible there was such an opinion current among philosophers, but was never thoroughly convinced of its truth until now.

Phil. You are still then of opinion that extension and figures are inherent in external unthinking substances?

Hyl. I am.

Phil. But what if the same arguments which are brought against Secondary Qualities will hold good against these also?

Phil. You are still then of opinion that extension and figures are inherent in external unthinking substances?

Hyl. I am.

Phil. But what if the same arguments which are brought against Secondary Qualities will hold good against these also?

Hyl. Why then I shall be obliged to think, they too exist only in the mind.

Celebrated neuro-thinkers like Daniel Dennett and Paul and Patricia Churchland are reluctant to give the "inside" of awareness or experience much explanatory weight, insisting that objective accounts of consciousness are far superior if you want to understand how the mind actually works. Such thinkers argue that subjectivity may have an undeniable intuitive appeal, but our own experience is an unreliable source of information, a morass of illusions and myths that cloud the quest to describe reality.

Yet in his 1991 book The Embodied Mind, co-written with Evan Thompson and Eleanor Rosch, the celebrated neuroscientist Francisco Varela insists that experience is an irreducible component of the study of the mind. "To deny the truth of our own experience in the scientific study of ourselves is not only unsatisfactory; it is to render the scientific study of ourselves without a subject matter." Varela and crew argue that while cognitive science continues to dig into the material foundations of cognition, researchers should balance their resulting models against the "disciplined, transformative analysis" of experience itself -- an analysis provided by, in their case, Buddhist meditation and philosophy. A serious student of Chogyam Trunpa, as well as the organizer of a number of formal dialogues between the Dalai Lama and Western scientists, Varela believes that Buddhism provides a sort of finely-tuned introspective tool that has been neglected in the West.