The Lure

Postscript

The question ‘Are we alone?’ is, at present, unanswered. Serious people deploy apparently sound arguments to reach opposite conclusions: these arguments, for and against, are given by the various fictional characters who populate The Lure.

The Galaxy is ancient. If civilisations were common there would have been adequate time for them (or even one of them) to have spread everywhere, including here on Earth. But they are not here, nor do we see any sign of them elsewhere. Therefore we are alone. This is consistent with the stunningly improbable series of chemical flukes needed to create life from dead matter.

The Galaxy is vast, and teeming with stars. There may be a hundred planets for every human being, many of which will be Earth-like. Given the speed with which life took hold on Earth, its development in the right environments must be commonplace. Given the selective advantages of a central nervous system all the way to a brain, intelligence must be found everywhere in the Universe where conditions are right. Therefore the Universe is teeming with intelligent life.

Both arguments are persuasive, but they can’t both be right!

At present, the search for extraterrestrial intelligence (SETI) beyond our solar system consists of a dozen or so independent programs spread around the globe. Strangely, nearly all of this funding is philanthropic, in spite of the fact that the question touches on some of the most profound issues of human existence (here). There are two types of search program, namely sky surveys and targeted searches. In a project funded by the Planetary Society and the SETI Institute, whole-sky data from the giant Arecibo radio telescope in Puerto Rico are routinely analysed by about four million computer owners worldwide, running a ‘screensaver’, background program. Another major sky survey, Project Argus, consists of about a thousand amateurs operating a number of small, ‘backyard’ radio-telescopes. Project Phoenix, on the other hand, uses the world’s largest radio telescopes. It is a targeted radio search, concentrating on about 1,000 nearby stars, that is within 155 light years of us. The project is well advanced, but so far it has met only the Great Silence.

Plans exist for a targeted search of 100,000 stars over an eight-year period. This may be a prelude to a search for signals from a million stars using the extremely powerful SKA, a square kilometre array of 500 to 1,000 radio telescopes yet to be built. Ultimately it is hoped to search a billion stars in the expectation of finding the strong, transient signal which will tell us that there are other sentient beings in the galactic wilderness.

These searches all take place at radio wavelengths. In recent years, however, a few searches involving small (again some almost backyard) optical telescopes have taken place for laser pulses coming from the nearest 1,000 or so stars. As we go to more and more energetic particles, more information can be packed into a signal of given duration. This leaves one with the nagging feeling that, maybe, civilisations a thousand or a million years older than ours may not communicate with such primitive devices as smoke signals, radio telescopes or lasers. It is true that the energy needed to send a signal increases pro rata with the energy of the carrier particle. However, the energy available at the start of the twentieth century was dwarfed by that available at its end (compare the Wright brothers’ Kitty Hawk with a Boeing 747), and it is reasonable to suppose that the huge energies required for particle beaming will be available to alien civilisations.

That there may be a subtle interplay between the Universe and the life it contains is hinted at by Freya (p.171). The fine tuning which she describes is real and baffling. It may imply that the universe we inhabit is only one of many, the whole ‘multiverse’ being an infinite ensemble of universes with different properties, only a tiny proportion of which have the properties to harbour life. Or it may be that our universe has arisen (if it ‘arose’ at all) as part of a process which allows new universes to grow within it, each with its own properties, some of them suitable for life. Or (unfashionable thought!) the Universe may have been created for the purpose of harbouring life. It has even been suggested that life itself structured the Universe to favour its own continuation. Whatever the merits of such ideas, we may well agree with Shakespeare’s Hamlet that

The bizarre ‘wheels of light’ at sea are real, and the descriptions quoted are genuine. They have no known explanation. Petrie’s apparently mad theorising about astral phenomena and altered states of consciousness in the Book of Revelation is in fact a respected opinion amongst Biblical scholars.

Bill Napier