Introductory Remarks and the Growing Interest in ETI

The idea that extraterrestrial intelligence could be behind some elements of the great mixture of experiences lumped together under the term "UFO phenomena" has rarely been seriously discussed by the scientific community s1Sagan & Page 1972 s2Hynek 1972 s3Condon 1969. It is natural that this silence has been taken by other academics and the educated public as an indication that the position is not worth taking seriously. Given the tenor of our debates upon extraterrestrial intelligence elsewhere in the galaxy, this is a peculiar and certainly inappropriate state of affairs. This paper will attempt an overview of the status quo of facts and hypotheses which are most relevant to the subject of ETI and the odds on life elsewhere visiting nearby space. It will try to place ufology and its extraterrestrial hypothesis into this context.

Since the 1960s, a growing group of scientists has directed a significant amount of thought and writing to the question of ETI. They have debated the odds of the existence of such beings, the possibility of their travelling between the stars, and the means of contact between them and ourselves. Carl Sagan and Frank Drake have become the leading proponents of the belief that our galaxy is teeming with intelligent life and technologically advanced civilizations s4MacGowan & Ordway 1966 s5Shklovskii & Sagan 1966 s6Sagan 1973 s7Drake 1976.

Despite the intelligence and prestige of many of the leaders of this optimistic view, the vision had an air of complexity yet lack of concreteness which made it easy to disregard as unfocused speculation. Many conservative scientists felt that the field of study was not a field at all. The major tool which has swung the atmosphere of opinion has been the "Drake Equation", constructed as a heuristic device by Frank Drake, and which has served well in generating discussion about specific issues where data of some sorts are available.

The Drake Equation is a mathematically simple string of multiplicative factors, as follows:

N = R_* f_p n_e f_l f_i f_c L

The definitions of the factors are:

• N : the number of currently extant hi-tech galactic civilizations;
• R₀ : the rate of galactic star formation;
• f_p : the fraction of stars which have planets;
• n_e : the number of earth-like planets per system;
• f_l : the fraction of earths which will form life;
• f_i : the fraction of ecologies which will evolve intelligences;
• f_c : the fraction of ETI which will develop civilization;
• L : the mean lifetime of an advanced civilization.

This mathematical "outline" has allowed discussants to split up the complex problem into more discrete bits upon which current science may have a say. Tentative conclusions from the last decade's debates are sometimes surprising in their concreteness and always interesting in their scientific, sociological, and psychological insights.

When one peruses the ETI literature, the following major discussions stand out:

1. the Drake Equation factors n_e, f_l, and L;
2. interstellar travel and "colonization waves";
3. time scales and extremely advanced societies;
4. ETI motivations and behaviors towards ourselves.

Taken as a piece, the literature tends toward the following vision: ETI occurs in great numbers of locations in our galaxy, and probably has the means and even the motivation for some degree of exploration and/or communication. A minority opinion holds that ETI is disinterested, paranoic, rare, or non-existent. What follows is a review of the major facts and points of issue in this dialogue.

It is intriguing when placed against the backdrop of the UFO phenomenon.