Life in the Loop: a Ringworld essay
Richard Brook Cathcart
The hallmark of Gaia theory is control
of Earth's surface to some significantly large degree by life – briefly,
life is in the loop (a biology-dominated planetary geologic rock cycle).
By AD 2100, demographers expect Earth's human populace
to begin to decline in number from its 21st century peak of 10 billion persons.
Still, Homo sapiens has been titled "the world's greatest evolutionary force." Our tool-using electromechanical civilization, to survive in the long-term, must spread life – however it is ultimately defined – and beautify the physical Universe. Mindful of the deadly physical threats imposed by mere existence in this Universe, life ought to be widely dispersed lest an extinctive mind-Gotterdammerung occur. Is it possible intelligent life will progress from being merely geologically in-the-loop to actually emerging from a star-bound hoop?
Figuratively, Gotterdammerung ("twilight of the Gods") extends to situations of world-shattering destruction marked by extremely chaotic alterations. Whilst "Music of the Spheres" is an ancient Greek concept, it was the German composer Richard Wagner (1813-83) who popularized this term when he chose it as the title of the last opera of his sequence Der Ring des Nibelungen/The Ring of the Nibelung (1876). Fantasy, because it may be unique to Homo sapiens, is an identifiable trait of which people can be proud. Described by mechanical engineers, a person is a 10-cycle, closed-loop, sensing, computing and performance system in a 100 kg chassis with a 75 W motor. This system has a normal duty cycle of 10 hours on to 8 hours off and is limited to a ~100-year design life. Intuition and inspiration aside, all science and art results from a 1.2 kg brain's thoughts, which most certainly include dreams, powered by quite small energy expenditures – usually ~5% of an individual's metabolic rate.
One such doable dream, disseminated as a science fiction novel, is a very popular book, Ringworld (1970) by Larry Niven (aka, Laurence van Cott Niven). Born in 1938, Niven created science fiction's most famous Big Dumb Object – a hoop-shaped machine that is discovered by Homo sapiens approximately 1,000 years hence encircling an imaginary star designated EC-1572. Ringworld was, evidently, created from all the materials that once naturally existed within the gravitational field of EC-1572; in other words, some kind of intentional geophysical Gotterdammerung occurred to create the new world named Ringworld!
Rings of dust and asteroids do circle stars – perhaps the observed ring that most resembles Ringworld in appearance is the star HR4796. Solid machine worlds with geometrical shapes like Ringworld could orbit Kerr black holes. A rotating Kerr black hole encircled at its equator by a spinning ring-city can provide a long-lasting source of energy; such a Kerr black hole-sited ring-city, converting dumped waste materials into useful energy, was diagrammed first by Charles Misner (b. 1932), Kip Thorne (b. 1940) and John Archibald Wheeler (b. 1911). In their learner's Exercise 33.10, "Angular momentum vector for infalling particle", in Gravitation (1970, at pages 907-913), they unambiguously demonstrated that a Ringworld of some kind is a practical civilization base. Properly, their rotating construct ought to be labeled a Kardashev type II civilization, a civilization built by masterful structural engineers. [Since 1969, Roger Penrose (b. 1931) envisions a civilization partially encrusting a Kerr black hole.]
Structural engineering is anything in the Universe that embodies the interaction of stress and strain; wherever there is gravity, there is stress and strain and, thus, all things must concern the structural engineer. The duty of all structures is to maintain the status quo and so each structure must somehow generate adequate deflective forces to oppose the loads that they have to carry because there is, and there can be, no truly rigid material. Imaginatively, Larry Niven transmuted planetary materials into "scrith," a new material of extraordinary strength able to resist the stress and strain caused by centrifugal forces. Situated exactly at the event horizon of a Kerr black hole, transiting material such as urban detritus sent into collision by intent may send its annihilation energy outward (away from the hole) to the intercepting Ringworld-like civilization; garbage, trash and other wastes sent into a Kerr black hole would permit the extraction of energy from the shell-region, called the ergosphere, located between the stationary limit and the event horizon. Lin-Xin Li at Princeton University Observatory announced, during AD 2000, his model for a Kerr black hole energy-production device (with an efficiency of ~29%) that can, theoretically, operate for an indeterminate period of cosmological time.
Larry Niven's novel Ringworld is located about a Sun-like star far from Earth's Sun. Ringworld mysteriously protects itself with an automatic movable anti-solar flare screen. It is a fictive ~2 × 1030 g topless box-shaped metal band around EC-1572's equator. Niven conjured a dense, unreflective, gray-colored metallic Ringworld construction material-dubbed with the invented appellation "scrith" – which endows Ringworld with material near-indestructibility. Now obsolete, a "crith" is the mass of one liter of hydrogen at 273.16 K and pressure of 101,325 N/m2. Someday, Niven's scrith may be manufacturable through quantum-mechanical bonding between artificial atoms; designer atoms formed of artificial molecules, may result from promising R&D pioneered since 1997 at the Walter Schottky Institute (founded 1986) in Munich, FRG. A perfected scrith might become the first uniform construction material humans ever get to work with! An 10 April 2000 report convincingly indicates that when an electron in a hydrogen atom is accelerated to nearly the speed of light, the electron behaves as if it were a large ring of electric charge around the atom's nucleus-pictured in computer simulations, it looks like Ringworld in sub-microscopic form!
The density of an atomic nucleus is ~1014 g/cm3 if the Earth had the same density, it would be a sphere ~240 m in radius. Supposedly abandoned by its alien macroengineer-constructors, a derelict Ringworld, with an area equal to ~3 × 106 Earth surfaces, awaits settlement by ~3 × 1015 humans or their descendents. Ringworld's locks and fluid pumps maintain brine and freshwater circulations; soil erosion must be minimized, and ultimately reversed, in order to maintain the arranged biological functions of the interconnected ocean, rivers and lakes. Since the inner surface of the open-top box is never averted from EC-1572, Ringworld cannot dissipate solar heat. Exterior finned radiators extend outward into interstellar space, lending Ringworld the visual appearance from a distance of a spiky hula-hoop. It might be assumed that Ringworld is prepared for a modification if its primary becomes a Kerr black hole! Since the star it uses as an energy resource is Sunlike, Ringworld will sometime have to shorten its length eventually when EC-1572 becomes a rotating Kerr black hole with a diameter of ~3 km! Ringworld may be safer for life than a Dyson sphere because it would be a more effective shield against high-energy radiation produced by any gamma-ray burster within < 200 million astronomical units. Made of fabulous scrith >1 km thick, Ringworld is a protective shelter for radiation-sensitive life.
If exploration of the Universe leads to the discovery of a usable nearby Kerr black hole, then what kind of biological and material science experiments can be done and what kinds of products can be made using a Ringworld facility as a central base of transformational operations? genetic engineering in interplanetary space aboard the Space Shuttle has demonstrated microgravity's utility in introducing DNA into living plant and animal cells. New kinds of carefully conducted biological experiments and, especially, materials research and processing may be accomplished in a Kerr black hole's mega-gravity field. There, a mega-gravity field >294 m/s2 will be useful in creating compressed metallic products, replacing old-fashioned explosive forming as, for example, "scrith plus"! Also, new kinds of solid explosives may result since a good explosive has high initial density so that as much material as possible fits into any given volume, and after detonation it turns into products that have the largest possible number of gas molecules. Structural engineering uses explosives to destroy as well as to construct things; in effect, Ringworld may become the source of life's neo-Big Bang!
1. Wolfgang Lutz, W. Sanderson and S. Scherbov, "The end
of world population growth," Nature 412: 5433-545 (2 August 2001).
2. Stephen R. Palumbi, "Humans as the World's Greatest Evolutionary Force," Science 293: 1786-1790 (7 September 2001).
3. Peter Nicholls, "Big Dumb Objects," pp. 118-119 in John Clute and P. Nickolls, The Encyclopedia of Science Fiction (1993, St. Martin's Press, NY).
4. Allen Tough, "Interstellar Contact: A Thousand-Year Perspective," Journal of the British Interplanetary Society 52: 324-327 (September-October 1999).
5. Li-Xin Li, "Extracting Energy from a Black Hole Through The Transition Region," The Astronomical Journal 540: L17-L20 (1 September 2000).
6. R.E. Wagner, Q. Su, and R. Grobe, "Relativistic Resonances in Combined Magnetic and Laser Fields," Physical Review Letters 84: 3282-3285 (10 April 2000).
7. Raymond J. Bula, R.A. Vierling, S.L. Goldman, "Genetic engineering in a microgravity environment," Chemical Innovation 30: 30-33 (January 2000).
8. Tsutomu Mashimo, "Exploitation of New Materials Processing in a Mega-gravity Field," Acta Astronautica 48: 145-151 (January-February 2001).
9. See the theme issue "Combustion science at the end of the millennium," edited by K.N.C. Bray and N. Nikiforakis, Philosophical Transactions of the Royal Society London A 357: 3481-3696 (15 December 1999).
10. This WWW site has data about Nivens Ringworld: