1980 00 00 Quarterly Journal of the Royal Astronomical Society - Vol 21 - Frank Tipler

Magazine Overview

This document is a scientific paper titled "Extraterrestrial Intelligent Beings do not Exist*" by Frank J. Tipler, published in the Journal of the Royal Astronomical Society, Volume 21, Issue 3, in 1980. The paper, received on November 15, 1979, argues against the existence of extraterrestrial intelligent beings based on the premise that if they existed and had the technology for interstellar communication, they would have already explored or colonized our solar system.

Introduction to the Argument

Tipler begins by acknowledging the long-standing debate about extraterrestrial intelligence, contrasting the views of astronomers and physicists who often advocate for their existence with evolutionary biologists who argue for Earth's uniqueness in harbouring intelligence. Tipler aligns with the biologists, stating that the probability of intelligence evolving on other planets is extremely low. He posits that any intelligent species capable of interstellar communication would also develop interstellar travel, leading to the exploration and colonization of the Galaxy within 300 million years. The absence of such evidence in our solar system is presented as proof of their non-existence. He aims to strengthen this argument by demonstrating that interstellar communication technology inherently leads to interstellar travel technology.

The General Theory of Space Exploration and Colonization

The paper outlines a strategy for space exploration and colonization that maximizes information gain while minimizing costs. This involves using "off-the-shelf" technology and available resources. The core concept is the "von Neumann machine," a self-reproducing universal constructor with human-level intelligence. Such a machine, coupled with advanced computer technology (expected within a century), could explore and colonize the Galaxy in less than 300 million years. The author emphasizes that computer technology, not rocket technology, is the current limitation for galactic exploration.

Tipler explains that a von Neumann probe, upon reaching a target stellar system, would use local materials to construct copies of itself and new engines. These copies would then be sent to nearby stars, repeating the process. This method would allow for the exploration of the entire Galaxy. The probe could also be programmed to conduct scientific research or even to colonize a system by constructing O'Neill colonies and synthesizing inhabitants from genetic information.

Astrophysical Constraints on the Evolution of Intelligent Species

Tipler applies the Drake equation (p = fp*ne*fi*fi*fe) to estimate the probability of intelligent life. He argues that while fp (probability of a star system having planets) and ne (number of habitable planets) might be determinable, fi (probability of life evolving) and fi (probability of intelligent life evolving) are difficult to measure due to the lack of a sufficient sample size (only Earth). However, he contends that if intelligent species develop interstellar communication technology, they would also develop interstellar travel within 100 years, thus expanding the sample size to include all older stellar systems. The absence of probes from these older systems implies that the product fifife must be very small, leading to the conclusion that Earth is likely the only technological civilization in the Galaxy.

He assumes that astrophysical factors influencing planet and star formation have not varied significantly over the Galaxy's history. Based on the number of stars older than 5.3 billion years and the absence of extraterrestrial probes, he concludes that the probability of communicating civilizations existing now is less than or equal to one, implying that we are it.

Motivations for Interstellar Communication and Exploration

Tipler questions why an intelligent species would develop the technology for interstellar communication but not attempt interstellar travel. He suggests that even if civilizations are short-lived (less than 100 years), the probes, once launched, would continue the exploration autonomously. He argues that the motivation for communication, such as exchanging information, provides an even stronger reason for exploration via probes, which have advantages over radio communication (e.g., not needing to guess frequencies).

He uses the example of Mars exploration, where probes were preferred over hypothetical communication methods like mirrors. Tipler asserts that, based on the principle of mediocrity and the natural dispersal behavior observed in all living things, advanced intelligent species would inevitably launch von Neumann probes for galactic expansion. This expansion is limited by technology, and he expects it to be a common behavior pattern among intelligent species.

Recurring Themes and Editorial Stance

The central theme of the paper is the argument against the existence of extraterrestrial intelligent beings, primarily based on the technological implications of interstellar communication and travel. Tipler's stance is highly skeptical of their existence, relying on logical deductions from technological capabilities and the absence of observable evidence. The paper advocates for a scientific, evidence-based approach, using mathematical models like the Drake equation and principles of astrophysics and evolutionary biology to support its conclusions. The concept of self-replicating probes (von Neumann machines) is presented as a key technological enabler for galactic colonization, which, if feasible, should have already occurred if other intelligent civilizations existed.

This document is a scanned page from a publication titled "EXTRATERRESTRIAL INTELLIGENT BEINGS," part of Volume 21, Issue No. 3, published in 1980 by the Royal Astronomical Society. The content is in English and focuses on theoretical considerations regarding the existence and potential activities of extraterrestrial intelligent life.

The Concept of Von Neumann Probes

The article begins by discussing the sufficiency of a single von Neumann probe for a species to colonize the stars. Such probes, capable of self-replication, could allow a species to survive existential threats like stellar death or nuclear war without necessarily displacing other species. They could, for instance, construct O'Neill colonies around stars that lack living organisms.

A significant concern raised is the potential for intelligent species to lose control of these probes. Due to the imperfection of reproduction, the control program could be omitted, leading the probes to act autonomously. The article outlines three ways this problem could be avoided:

1. Program Integration: The control program could be so deeply integrated into the probe's total program that its omission would render the probe non-functional, similar to constraints in recombinant DNA technology.
2. Colony Formation: Probes could be programmed to form colonies of the inventing species within the target stellar system. These colonies would then be responsible for managing any runaway probes.
3. Indifference to Control Loss: The inventing species might not care if the probes gained independence. The article posits that as civilization advances, racism declines, and rights are extended to more beings, von Neumann machines, as intelligent entities, might be recognized as fellow intelligent beings with rights.

However, if the inventing species retained racist tendencies, they might view other 'flesh and blood' species as 'non-people.' In such a scenario, they might either avoid communication to prevent cultural contamination or launch von Neumann probes to colonize the galaxy preemptively or to destroy other intelligent species. This strategy would be particularly relevant if the 'biological exclusion principle' (two species cannot occupy the same ecological niche) applies to intelligent species, with a solar system representing an ecological niche.

The article also notes that if a species is not concerned about alien ideas but wishes to avoid contaminating other cultures, it might refrain from radio contact. However, probes offer a way to study alien species covertly.

Evidence and the Zoo Hypothesis

The author then considers the possibility that von Neumann probes from extraterrestrial intelligent species are already present in our solar system. The probability of a probe arriving within the last 20 years is estimated at 10⁻⁹. This probability, the article suggests, is greater than the probability of extraterrestrial intelligent beings evolving in the first place.

Another possibility discussed is the 'zoo hypothesis,' where intelligent beings are present but deliberately conceal their existence. This hypothesis could be tested by attempting to intercept communications or by searching for the waste heat (infrared excess) generated by von Neumann machine activities, particularly in the asteroid belt where material is abundant. The absence of observed extraterrestrial ships of any type on Earth is presented as evidence against this scenario. Furthermore, if intelligent beings had arrived billions of years ago, they would have had no reason to hide their technology, and the asteroid belt would likely be covered in artifacts by now.

The Inconclusive Nature of Evidence and Psychological Motivations

Despite the strong evidence against the presence of extraterrestrial intelligent beings, the article acknowledges that the evidence is not "utterly conclusive." Advanced beings could still be present and undetectable. The author draws a parallel between the belief in extraterrestrial intelligent beings and the belief in UFOs as extraterrestrial spaceships, suggesting that the underlying psychological motivation for both might be the same: a desire for "miraculous interstellar intervention" to save humanity from itself.

The Anthropic Principle and the Immensity of the Cosmos

The belief in extraterrestrial intelligent beings is linked to the perceived immensity of the cosmos. The article references the 'Anthropic Principle,' which posits that many aspects of the Universe are determined by the requirement that intelligent life must exist. This principle suggests that the Universe must contain a vast number of stars (estimated at 10²⁰) to ensure the existence of even a single intelligent species, thus making the existence of only one such species not surprising.

References

The document includes an extensive list of references, indicating that the article is based on a broad range of scientific literature concerning astronomy, biology, evolution, artificial intelligence, and the search for extraterrestrial intelligence (SETI).

Recurring Themes and Editorial Stance

The recurring themes in this article are the theoretical possibilities of extraterrestrial intelligence, the technological means by which they might explore or colonize the galaxy (specifically von Neumann probes), and the challenges of detecting such life. The author's stance appears to be skeptical but open-minded, presenting arguments against the existence of detectable extraterrestrial intelligence while acknowledging the limitations of current evidence and the psychological appeal of such beliefs. The article leans towards the idea that while the universe is vast, the conditions for intelligent life may be rare, or that intelligent life, if it exists, may not be detectable or may choose not to interact with us.