John Barrow has been on my mind these past few days, for reasons that will become apparent in a moment. In my eulogy for Barrow (1952-2020), I quoted from his book The Left Hand of Creation (Oxford, 1983). I want to revisit that passage for its clarity, something that always inspired me about this brilliant physicist. For it seemed he could render the complex not only accessible but encouragingly pliable, as if scientific exploration always unlocked doors of possibility we could use to our advantage. His was a bright vision. The notion that animated him was that there was something in the sheer process of research that held its own value. Thus:

Could there be any shortcuts to the answers to the cosmological questions? There are some who foolishly desire contact with advanced extraterrestrials in order that we might painlessly discover the secrets of the universe secondhand and prematurely extend our understanding. Such a civilization would surely resemble a child who receives as a gift a collection of completed crossword puzzles. The human search for the structure of the universe is more important than finding it because it motivates the creative power of the human imagination.

You can see that for Barrow, the question of values was not separated from scientific results, and in a sense transcended the data we actually gathered. He goes on:

About 50 years ago a group of eminent cosmologists were asked what single question they would ask of an infallible oracle who could answer them with only yes or no. When his opportunity came, Georges Lemaître made the wisest choice. He said, “I would ask the Oracle not to answer in order that a subsequent generation would not be deprived of the pleasure of searching for and finding the solution.”

Image: Cosmologist, mathematician and physicist John D. Barrow, whose books have been a personal inspiration for many years. Credit: Tom Powell.

Leave it to Lemaître (and Barrow to quote him) as we reach beyond the immediately practical to unlock what it is about human experience that compels us to push into new terrain, whether it be physical exploration or flights of the imagination as we pursue a new hypothesis about nature. Barrow comes to mind because we’ve just been talking about the scales by which a civilization can be measured. Some of these are well established, as for example the Kardashev scale, with its familiar Types I, II and III keyed to the scale of a civilization’s energy use. In Clarke’s The Fountains of Paradise we find an alien scale based on the use of tools. It’s possible to imagine other scales, and Barrow’s own contribution takes us into the nano-realm.

As best I can determine, Barrow first floated the scale in his 1998 book Impossibility: The limits of science and the science of limits (Oxford University Press). Inverting Kardashev, Barrow was interested in a civilization’s ability to control smaller and smaller things, relying on the observed fact that as we have explored such micro-realms, our technologies have proliferated. Nanotechnology and biotechnology are drawn out of our ability to manipulate matter at small scales, and in fact the development of nanotech is one marker for a Barrow scale IV culture.

Barrow I: The ability to manipulate objects at the same scale as the person or being involved. In other words, simple activities involving basic tools.

Barrow II: The control of genetic information.

Barrow III: The ability to control molecules.

Barrow IV: The ability to control individual atoms.

Barrow V: The manipulation of atomic nuclei..

Barrow VI: Control of elementary particles.

Barrow Omega (Ω): The ability to control fundamental elements of spacetime.

Table: Energetic and inward civilization development. Kardashev’s (1964) types refer to energy consumption; Barrow’s (1998, 133) types refer to a civilization’s ability to manipulate smaller and smaller entities. Credit: Clément Vidal.

I’ve drawn the above table from a paper by French philosopher and SETI scientist Clément Vidal, who is one of the few who have explored this realm (citation below). Here we get both Kardashev and Barrow at once, a convenience, and central to Vidal’s argument that black holes are going to draw advanced civilizations to extract their energies and explore what he calls “the computational density of matter.” On this score, it’s interesting to note that Freeman Dyson proposed in 1979 that a civilization exploiting time dilation effects near black holes could survive effectively forever (a later revision had to take into account the accelerating expansion of the universe).

What all this means for SETI is intriguing – almost punchy – and I’ll send you to Vidal’s superb The Beginning and the End: The Meaning of Life in a Cosmological Perspective (Springer, 2014) for a deep dive into the concepts involved. But consider this for a starter: Dysonian SETI assumes civilizations far more advanced than our own, the reasoning being that their works should be apparent even at astronomical scales. Thus searching our astronomical data as far back as we can could conceivably flag an anomaly that merits investigation as a possible civilizational marker.

What Clément Vidal has been investigating is where such markers would turn up, and for this he deploys the scales of both Kardashev and Barrow. I think the easiest assumption is that we would find an alien civilization at its home world, but of course this needn’t be the case. Vidal speaks of ‘attractors’ as those sources of energy that an advanced civilization would increasingly exploit. Take a culture a billion years older than our own and ponder energy needs that might require it to exploit things like the energies of close binary neutron stars or black holes themselves. Such a civilization would be far flung, with operations well beyond its local group of stars.

Now ponder Barrow Type Ω. This ‘omega’ culture is free of the constraints of spacetime, having achieved the ability to manipulate both. It’s anyone’s guess whether such a civilization would be noted by achievements on a truly celestial scale, or whether its works would actually be embedded in the nature of space and time themselves, so that to us they appear the simple functioning of nature. In this mode of thinking, the more advanced a civilization becomes as it moves up the Barrow scale, the more it begins to effectively disappear. Barrow thus channels Richard Feynman and anticipates Lee Smolin’s notions about cosmological evolution, a kind of self-selection for universes.

I’m going to swipe the chart below from Vidal’s 2010 paper on black hole attractors, showing the entertaining fact that as he puts it, “from the relative human point of view, there is more to explore in small scales than in large scales.”

Table: That humans are not in the center of the universe is also true in terms of scales. This implies that there is more to explore in small scales than in large scales. Richard Feynman (1960) popularized this insight when he said “there is plenty of room at the bottom”. Figure adapted from (Auffray and Nottale 2008, 86). Credit: Clément Vidal.

Futurist John Smart has dug into what he calls STEM Compression, with STEM in this case meaning Space/Time/Energy/Matter, and the compression being the idea that in terms of density and efficiency, we can as Vidal puts it “do more with less.” For going deeper into the Barrow scale, we see that as things get smaller, we are not hampered by the speed of light problem. In fact, our endgame barrier is at the Planck scale. A Kardashev II civilization extracting energy from a rotating black hole using technologies far up the Barrow scale may well be indistinguishable from an X-ray binary of the sort that has been cataloged in the astronomical literature.

Such speculations are on the far edge of SETI (and again, I refer you to Vidal’s book), but it’s also true that whether or not extraterrestrial civilizations exist, our own ability to chart futures for an expanding civilization may well come in handy if we can somehow punch through whatever ‘great filter’ may be out there and become a species that survives on the scale of deep time. There is no knowing whether this is even possible, and it may be that the galaxy is filled with the ruins of those who have gone before us.

It is also true, of course, that no one may have gone before us. Maybe N really does equal 1. But I return to Barrow: “The human search for the structure of the universe is more important than finding it because it motivates the creative power of the human imagination.” And the human imagination is currency of the realm in matters like these.

The Vidal paper is “Black Holes: Attractors for Intelligence?” presented at the Kavli Royal Society International Centre, “Towards a scientific and societal agenda on extra-terrestrial life”, 4-5 Oct 2010 (abstract). The Dyson paper is “Time Without End: Physics and Biology in an Open Universe,” Review of Modern Physics 51: 447-460 (abstract). My eulogy for Barrow is On John Barrow. John Smart contributed a fascinating essay on cosmic evolution in these pages in The Goodness of the Universe.