Mining the Depths

The ultimate source of power?  Published by Fontana 1974.  Cover photograph of the Trifid Nebula by Rolf Schurch/Camera Press

The ultimate source of power? Published by Fontana 1974. Cover photograph of the Trifid Nebula by Rolf Schurch/Camera Press

Our civilization needs a lot of power to survive. And if our descendants eventually spread throughout the Galaxy, their energy requirements will dwarf anything we need today. Every possible source will need to be considered, and they will almost certainly turn their attention to those concentrations of matter and energy where the gravitational field is so strong that spacetime is completely curved back on itself and nothing, not even light, can escape – black holes.

In one of the earliest popular accounts on the subject published in 1973, Black Holes: The End of the Universe?, John Taylor, professor of mathematics at King’s College London, devoted a chapter to the challenging topic of “taming black holes”. He discussed several approaches to extracting the gravitational energy that could be considered as existing at the black hole’s surface, possibly from the radiation that might be dispersed when two or more black holes undergo fusion, and the potential for creating small black holes that might be usable as sources of power.

Professor Taylor was not too optimistic, but recognised that one has “to be careful about blanket statements about what can or cannot be done in these matters.” Amazing developments in science and technology may indeed become realities in the future and, in one of its early issues, the magazine Omni published an article Star Power for Supersocieties (Omni, April 1980). Here, the science fiction writer and commentator Jonathan V Post described a future mission approaching the accretion disk of an immense spinning black hole.

As a transmitter of gravity waves, the black hole in Post’s imagination could be the hub for a galaxy-wide communications system, but also providing the long-term solution to a galactic civilization’s energy needs. He gives us the image of large stars being triggered into supernova explosions, and the resulting black holes undergoing fusion to generate power. Black hole technology is seen as the entry point into a true Kardashev Class III society – a civilization living with a galactic level of energy.

In his 1974 postscript to his book, Professor Taylor referred to the then recent suggestion by Stephen Hawking that some particles could escape the intense gravitational field at a black hole’s event horizon as a result of quantum tunnelling – the phenomenon that has since been called “Hawking radiation”. This raises the possibility of “mining” this radiation whilst, for obvious reasons, staying at a suitably safe distance oneself.

In Can We Mine a Black Hole? (Scientific American, February 2015), Adam Brown, a theoretical physicist at Stanford University, talks about the possibility of extracting thermal energy through lowering down to the event horizon a variation on the space elevators which Arthur C Clarke made familiar to us in his 1979 novel The Fountains of Paradise, and which were discussed in last month’s BIS symposium on the subject. Dr Brown provides a sense of the potential methods that could be used in such an endeavour, but sadly concludes that even the strongest material that is ever likely to be available using foreseeable technology – the fundamental strings that exist as a consequence of string theory – will not be strong enough to resist the gravitational pull at the event horizon. The string might just about be able to support its own weight, but not that of any cargo as well.

So it doesn’t look too hopeful, but the imagination of our descendants may yet rise to the challenge in ways that we can’t envisage today. Or perhaps black hole technology may one day become a reality. As Professor Taylor put it so succinctly in his 1973 book, “To have one’s mind boggled at least once per day is a very important part of increasing flexibility and dispelling mystery in our attitude to the world around us.” Well put, professor.

Richard Hayes, Assistant Editor (Odyssey)

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