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Is it ethical to transmit powerful radio signals?

Some researchers in the Search for Extraterrestrial Intelligence (SETI) seek to invite a response from alien civilizations by transmitting powerful signals into space. Others have suggested this is a foolish, or even dangerous endeavor. What are the ethical implications of such messaging? Jason T. Wright, associate professor of astronomy and astrophysics, provides an ethical response to this issue.
by wav103 Nov 26, 2018

In partnership with the Rock Ethics Institute, Penn State Today’s feature column, "Ask an Ethicist," aims to shed light on ethical questions and issues. Each article in this column will feature a different ethical question answered by a Penn State ethicist. We invite you to ask a question by filling out and submitting this form. An archive of the columns can be found on the Rock Ethics Institute website. 

Question: Some researchers in the Search for Extraterrestrial Intelligence (SETI) seek to invite a response from alien civilizations by transmitting powerful signals into space. Others have suggested this is a foolish or even dangerous endeavor.  What are the ethical implications of such messaging? 

Jason T. Wright, associate professor of astronomy & astrophysics responds: The Search for Extraterrestrial Intelligence (SETI) is a field of astronomy, most popularly illustrated by the character Ellie Arroway in the film Contact, who used powerful radio telescopes to “listen” for radio transmissions in space that might come from alien civilizations. The plausibility of such communication was highlighted in 1974 when astronomers sent a 1 Megawatt signal into space, encoded with information about Earth. This form of SETI has been called “Messaging to Extraterrestrial Intelligences” or “METI”. Of course, humans regularly send weaker signals into space, in the form of television and radio broadcasts and the like, but METI researchers seek to send much stronger, more targeted signals.  

Are these activities ethical? Many SETI researchers think not, arguing that sending powerful, messages to space should be done in a globally representative way. Others go farther, arguing such activities are inherently dangerous because they seek to attract the attention of potentially hostile or otherwise dangerous aliens.  

To assess the morality of METI, let’s review a summary of some relevant facts and factors in the controversy.  First, humanity has been inadvertently broadcasting its existence through radio and radar for nearly 100 years, although not in a targeted or deliberate way. Second, there are other indications that Earth has life and that our existence may already be detectable from interstellar distances, especially by a sufficiently advanced civilization. Next, the timescales involved are so long that the duration of radio signal travel time to the nearest star is years, the radio signal travel time for most stars in the Milky Way is hundreds of thousands of years. The physical travel time is even longer. 

Additionally, we do not know about the intentions, reactions, locations, threat levels, or existence of any alien civilizations, and can really only guess about them. Many have argued that alien civilizations would be likely to be benevolent, malevolent, or indifferent to our existence.  Benevolence or indifference do not necessarily imply harmlessness. Astronomers generally agree that any alien civilizations capable of detecting our signals will be much older than humanity, potentially billions of years old, and therefore interaction with such a civilization may have profound and permanent consequences for all life on Earth. 

In addition to the uncertain consequences of being noticed, we cannot even quantify the likelihood of our discovery by alien civilizations as a function of the strength of our broadcasts. Beyond the fact that more powerful transmissions are more likely to be detected, we do not know what levels of transmissions are “safe” from detection by extraterrestrials. 

Finally, this is not just an international issue, but an intergenerational one since a response to our signals may not arrive for centuries.  The stakeholders are all of humanity, including future humans, and all current and future life on Earth. 

Based on the facts, what are the options?  Some are to support METI efforts on an international scale, to ignore them, to regulate such deliberate transmissions, or to regulate all electromagnetic transmissions from the Earth.  

Because of the uncertainty, weighing these options is difficult. The potential for harm from malevolent aliens is minimized for the more restrictive options and maximized for those that result in more METI, but in an unquantifiable way.  At the same time, the potential for benefit from contact follows the same pattern.  Harm in the form of inconvenience to ordinary activities involving electromagnetic radiation (including radar and cell phones) increases with tighter restrictions on their use. 

Absent contact with an alien civilization, the “regulate METI” option, is the most publicly defensible option for two reasons.  First, it does much to satisfy the Precautionary Principle (reducing potential harm) without interfering with other aspects of everyday life (minimizing certain harm).  It also preserves our options in the future. Regulations on METI can be reversed, but signals sent into space cannot be taken back. 

In short, a cost-benefit analysis of restricting transmissions is impossible given the unknown probability of an unknown consequence, with essentially unlimited upside and downside to attracting attention. It is therefore unlikely that this consideration could or should influence non-METI activities. My personal best guess is that METI activities will have a small but finite chance of triggering or accelerating unknowable but profound changes on Earth due to alien contact at some point in the future. 

An essential component of any ethical analysis is to ask the question, "What can we do to make this choice easier—or obviate it—in the future?". The above calculus can be changed if we were to learn more about alien life in the Galaxy, or if the social cost of restricting non-METI transmissions were low.  As we move to a more “wired” world with optical fibers and tight optical frequency communication replace strong radio broadcast transmission our choices will become easier. Our ignorance about life in the universe can be addressed by SETI, which seeks to first discover the alien civilizations that we might contact, and by the broader field of astrobiology, which seeks to understand the prevalence and origin of life in the Galaxy. 

Today, this topic does not have the visibility or urgency needed to trigger governmental or international discussion or regulation, and the high uncertainties involved may mean significant regulatory effort is not warranted. As a result, groups such as METI International are essentially free to operate, over the objections of others in the SETI community. Other aspects of this topic, such as “who speaks for Earth?” and the content of such messages, have their own ethical dimensions and are under active discussion, for instance by Breakthrough Message

Jason T. Wright is an associate professor of astronomy & astrophysics at the Center for Exoplanets and Habitable Worlds. He studies exoplanets, their host stars, and does some work in SETI. 

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Note: The "Ask an Ethicist" column is a forum to promote ethical awareness and inquiry across the Penn State community. These articles represent the interests and judgments of each author as an individual scholar and are neither official positions of the Rock Ethics Institute nor Penn State University. They are designed to offer a possible approach to a subject and are not intended as definitive statements on what is or is not ethical in any given situation. Read the full disclaimer.