© 1975-1979, 2008 Robert A. Freitas Jr. All Rights Reserved.

Robert A. Freitas Jr., Xenology: An Introduction to the Scientific Study of Extraterrestrial Life, Intelligence, and Civilization, First Edition, Xenology Research Institute, Sacramento, CA, 1979; http://www.xenology.info/Xeno.htm

19.2  Extraterrrestrial Habitat Engineering

Most of the discussion thus far has centered on the technical advances that could be achieved by Type I civilizations. Domiciled on a planet, living space will not be a major problem for such cultures. But emergent Type II societies will find no such ready-made living quarters in orbit. A species that wishes to expand its energy base and move into space must learn how to design and construct its own artificial habitats with a closed ecology and a controlled environment.

Yet ultimately the key to all technological accomplishment is energy. We have discussed this at great length in an earlier chapter, but it is now necessary to make explicit the critical difference between energy and power.

Simply stated, energy defines what a civilization can do whereas power defines how fast the civilization can do it. The distinction is important because the maximum technical achievement of any race is energy-limited, not power-limited.

In Chapter 15, in the interests of straightforward exposition, we made the tacit assumption that the rate of hydrogen fusion burning in stars was the maximum rate at which energy could be delivered to a technical culture from its sun. This assumption may not be valid for many advanced extraterrestrial societies.

Table 19.1 gives the total energy available to each class of civilization. The alert reader will have noticed that the energy figures on the one hand, and the power and lifetime figures on the other hand, cannot be reconciled. The reason for the discrepancy is this: Some alien cultures may choose to use up their total energy reserves in a manner which is far more efficient than a stellar furnace normally permits. In other words, by tampering with the normal processes within its sun a technical civilization can increase the total amount of energy that is available to it. Over its normal lifespan the typical star will convert its hydrogen to energy with a net lifetime efficiency of perhaps 0.06% -- a far cry from the 1% efficiency that may be had if the aliens turn off their sun and use their own fusion plants to burn the fuel.

Furthermore, ETs may elect to burn their hydrogen legacy at a faster rate than natural processes would normally allow. This will inevitably result in a shorter lifetime for the civilization, but this penalty is offset by the grander technological feats which may be accomplished with the vastly greater power expenditure (Table 19.2). To take a simple example: By accepting a lifetime of only one million years, and by tampering with its sun, a Type II civilization should be able to boost its useful power output to 6 x 10³¹ watts -- an increase of nearly six orders of magnitude over the nominal value.

The situation is rather like a suicide mission, Since shortened life has been accepted, one is free to devote more resources to the present. There is much less future to save for. While this may be viewed as irresponsible by some, it may also be argued that it is better to experience a brief but glorious career than a drawn-out bland existence.

In the final analysis, an intelligent race that chooses to expand into space is ultimately limited only by the amounts of energy and raw mass that are available to it.

Last updated on 6 December 2008