Seminar and Journal Club

Amedeo Balbi
February 13, 2025
Zoom recording

Abstract:
The detectability of extraterrestrial technosignatures—and, by extension, the success of the search for extraterrestrial intelligence (SETI)—is profoundly influenced by their longevity. This talk delves into the pivotal role of technosignature duration and its relationship to the lifespan of the civilizations that produce them. I explore how assumptions about the probability distribution of technosignature longevity shape both the likelihood of detection and the characteristics of the technosignatures most likely to be observed. Finally, I address the biospheric bottlenecks that influence the emergence of technology, as well as the thermodynamic constraints on planetary habitability imposed by energy-intensive civilizations, and how these factors may ultimately limit the longevity of both civilizations and their technosignatures.

Niklas Döbler
February 6, 2025
Zoom recording

Abstract:
Since 2020, I have taught a class called “Why does ET want phone home? Introduction to exopsychology” at the University of Bamberg, Germany. It was part of the curriculum for psychology majors in Bachelor’s and Masters. Participants ranged from first-year students to senior-level students. In this talk, I give an overview of the development of the course, used literature, practical exercises, and lessons learned. This may serve as inspiration for non-astronomy SETI classes, but also how to enrich the astronomical curriculum with perspectives from social science and psychology.

Eddie Schwieterman
January 30, 2025
Zoom recording

Abstract:
The introduction of artificial, long-lived, highly potent greenhouse gases has been proposed as one method to terraform Mars in our Solar System, altering a climate that is too cold to support a global biosphere to one that can. Could current and future observatories identify such a “terraformed” world in a nearby exoplanetary system? This talk will examine the potential for a representative subset of these gases (CF4, C2F6, C3F8, SF6, and NF3) to generate atmospheric signatures detectable with JWST and future space-based telescopes such as the European Large Interferometer for Exoplanets (LIFE) mission concept. While these gases are present in Earth’s atmosphere today as passive byproducts of industrial processes in trace (and therefore weakly detectable) abundance, the purposeful alteration of planetary climate would necessitate quantities of these gases that would drastically impact the planet’s thermal infrared spectrum. We find that such signatures would rival or exceed those of traditional prospective biosignature molecules in the Mid-IR, such as CH4 and O3. The talk will broaden to examine the complementarity of searching for biosignatures and technosignatures, which exist on the same astrobiological continuum, and explore the near-term preparatory and precursor science required to aid these searches.

Steven Dick
December 12, 2024
Zoom recording

Abstract:
The discovery of what I have called a “Biological Universe” full of life would have substantial effects not only on science, but also on society at large, including philosophical, theological, and ethical impacts (Dick, 1996; Dick, 2018). This presentation discusses systematic approaches to those questions from the point of view of history, the nature of discovery, and the promise and pitfalls of analogy, and surmises what the impacts might be under differing scenarios. We also argue based on what I call the Intelligence Principle, “the central principle of cultural evolution,” that it is highly likely we live in a postbiological universe full of artificial intelligence (Dick, 2003). The existence of postbiological superintelligences has implications for SETI, for post-detection protocols, and for our future interactions with life in all its forms. All of these implications require further interdisciplinary study from the natural science, social science and artificial intelligence communities.

Sean Raymond
November 14, 2024
Zoom recording

Abstract:
Exoplanet systems come in a variety of shapes and sizes. Yet not all possible arrangements exist within the current sample. In this talk, I will first describe the current paradigm of planet formation and the resulting orbital architectures of planetary systems, including exoplanets and the Solar System. Then we will explore planetary systems that are dynamically stable but do not appear to form naturally (at least, with our current models). These include multi-resonant systems (reminiscent of Trappist-1, but with period ratios chosen to produce integer sequences of mathematical importance), as well as exotic configurations (such as many-planet co-orbital systems). There exists a zoo of planetary systems that are unusual but stable for billions of years, and that would even survive their host star’s post-main sequence evolution. The question becomes, what would a ‘non-natural’ system represent — a beacon indicating the presence of an advanced civilization, or some as-yet-unknown formation process?

Daniela de Paulis
November 7, 2024
Zoom recording

Abstract:
On 24 May 2023, a simulated extraterrestrial radio signal was transmitted towards Earth by the Trace Gas Orbiter, a spacecraft of the European Space Agency orbiting Mars. The signal was received by the Green Bank Telescope and the Allen Telescope Array in the USA and by the Medicina Radio Antenna in Italy. The event was part of the interdisciplinary project A Sign in Space and was streamed live by the SETI Institute, with thousands of people watching in real time.

A Sign in Space started in late 2018 and was developed in collaboration with researchers at the Green Bank Observatory, the Italian National Institute for Astrophysics (INAF), the SETI Institute, and the European Space Agency over a period of four years.

The project simulates one of the possible scenarios following the reception of a confirmed radio signal from an extraterrestrial civilization. In the scenario envisioned in the project, scientists release the data of the signal in the public domain, asking people from around the world and with different skills, different expertise and various cultural backgrounds, to decode and interpret its content. A Sign in Space stages one of the possibly most radical events, in which humankind attempts to create meanings around a message crafted by an extraterrestrial intelligence.

Since the release of the signal data in the public domain on 25 May 2023, an international community of enthusiasts has been attempting to decode and assign meanings to the message designed for the project. Over the past months, hundreds of interpretations have been proposed and thousands of social media posts have been created in the ongoing decoding effort.

The global outreach of the project has been supported by workshops facilitated by the SETI Institute, and featuring various perspectives on SETI research from around the world, including those from aboriginal communities, from the Arab countries, China and South America.

A Sign in Space reached millions of people from 175 countries, through a global media coverage and various social media channels. The talk is presenting the preliminary media and cultural impact of the work and its potential benefit for SETI research, after one year since the public launch of the project.

Naoki Seto
October 10, 2024
Zoom recording

Abstract:
We discuss a Galaxy-wide coordinated signaling scheme in which a SETI observer needs to examine only a small fraction of the sky. The target sky directions are determined over time, based on high-precision measurements of conspicuous astronomical events within the Galaxy. In several respects, such a coordinated scheme would be beneficial for both transmitters and observers, and may have already been widely adopted as a tacit adjustment. As potential candidates for these conspicuous astronomical events, we consider future binary neutron star mergers and past supernova explosions recorded over the last ~2000 years. Additionally, we discuss a similar method for technosignature search in the direction of the Galactic center.

Brian Lacki
September 26, 2024
Zoom recording

Abstract
With their postulated ability to replicate through interstellar travel, technological societies may be unlike any astrophysical phenomenon we have observed. If true, different galaxies could have completely different technosignature profiles, a result of different histories. I introduce the concept of metasocieties, a collection of societies with shared influences described by a distribution function. This talk presents my recent work applying point process theory to the “haystack” of metasocieties, societies, and broadcasts. I contrast the “individualist” methods of typical SETI, looking for individual signals rising above the noise, to “collective” methods that look for the combined effects of a population. The problem of confusion, in which many overlapping signals prevent detection of any one of them, is addressed, as well as limits from the total luminosity of a galaxy. I close with thoughts on galactic ecology and the Fermi Paradox.

Gabriella Contardo
September 12, 2024
Zoom recording

Abstract:
Stellar infrared excess usually indicates the presence of debris disks or dust around a star. While common in young stars due to their protoplanetary disks, extreme IR excess in older stars is more atypical and could come from either rare or short-lived events. Recent works have investigated such excess at around 5-12μm wavelengths, finding around 20 candidates (“occurrence rate” of 0.01%) with fractional luminosities around 0.02, some tentatively associated with planetary collisions. These extreme “anomalies” are of interest as they potentially sit in an under-populated region of the “disk evolution” path depending on the stellar ages. They could also provide indirect observations of planetary systems. Interestingly, another possible source (while more speculative) of IR excess is mega-structures such as Dyson spheres or swarms. However, distinguishing them from natural processes wouldn’t be trivial. Expanding our set of candidates and our knowledge of such objects is thus crucial. Previous searches have focused on using WISE data notably in the W3 band (12μm) with high SNR requirement, dramatically limiting the amount of data. We propose in our work to rely only on the W1 and W2 bands (3.4-4.6μm) combined with Gaia DR3 and 2MASS, thus unlocking a much larger amount of data, at the cost of detecting only “extreme” excesses showing in those bands. We focus on Sun-like stars (FGK) on the main sequence, leading to a catalog of 4.9M stars. Our search is designed as a data-driven contextual anomaly detection pipeline: to identify outlier candidates, we use a combination of prediction errors from a set of Random Forests trained on our catalog, and statistics using prediction errors of similar neighbouring points. Our approach bypasses the need for actual stellar modelling while providing a high detection sensitivity, crucial in our case. We identify 53 candidates with fractional luminosities between 0.005 to 0.1, consistent with previous EDDs candidates and potential planetary collision events.