The evolution of life in the Universe: are we alone?

Abstract

Abstract. In his book Plurality of Worlds, Steven J. Dick (1984) has chronicled the millennia of discourse about other inhabited worlds, based upon deeply held religious or philosophical belief systems. The popularity of the idea of extraterrestrial life has waxed and waned and, at its nadir, put proponents at mortal risk. The several generations of scientists now attending this General Assembly of the International Astronomical Union at the beginning of the 21 st century have a marvelous opportunity to shed light on this old question of habitable worlds through observation, experimentation, and interpretation, without recourse to belief systems and without risking their lives (though some may experience rather bumpy career paths). The newly-named and funded, multi-disciplinary field of astrobiology is extremely broad in its scope and is encouraging IAU members to learn and speak the languages of previously disparate disciplines in an attempt to answer the big picture questions: 'Where did we come from?', 'Where are we going?', and 'Are we alone?' These are questions that the general public understand and support, and these are questions that are attracting students of all ages to science and engineering programs. These questions also push the limits of modern instrumentation to explore the cosmos remotely across space and time, as well as to examine samples of interplanetary space returned to the laboratory and samples of distant time teased out of our own Earth.Within my personal event horizon, the other planetary systems long-predicted by theorists have been uncovered, along with many whose structures were not predicted. The 'just-so' conditions requisite for the comfort of astronomers have been understood to be only a very narrow subset of the conditions that nurture extremophilic, microbial life. Thus the potentially habitable real estate beyond Earth has been greatly expanded and within the next few decades it may be possible to detect the biosignatures or technosignatures of inhabitants on distant worlds, should there be any.

Relative Likelihood of Success in the Search for Primitive versus Intelligent Extraterrestrial Life

“…If we were merely interested in finding extraterrestrial life, regardless of its complexity, the two outcomes could be treated on an equal footing. Yet, there is a distinction because the impact of detecting technological intelligence is not the same as that of finding microbes (Tarter, 2007;Kite et al, 2018). Evidently, there would be an anthropocentric bias since we are probably more predisposed to rank technological intelligence higher because we categorize these traits (rightly or wrongly) as "human".…”

Alien Mindscapes—A Perspective on the Search for Extraterrestrial Intelligence

“…Nevertheless, the Drake equation was essentially the first roadmap and the first holistic vision of the search for life in the Universe (Tarter, 2007)—an approach that would become the trademark of the nascent field of astrobiology 35 years later (Des Marais et al , 2008). Even at this seminal time, it captured in one expression the notions of extrasolar planetary systems, habitable zones, habitable planets and environments, the transition from chemistry to biology, life on and beyond Earth, and the evolution of intelligence, civilization, and technology.…”

“…, Tarter, 2007). SETI uses the Kepler catalog and ground-based telescope databases to target high-priority candidates.…”

Unsupervised Distribution Learning for Lunar Surface Anomaly Detection

“…The search for so called technosignatures in our Solar System and beyond has gained new attention recently [1]. Here, technosignatures are physical properties or effects that provide scientific evidence of past or present extraterrestrial technology [2]. According to NASA the search for technosignatures should be performed in parallel to the search for biosignatures in the field of astrobiology, as technosignatures could reveal the existence of intelligent life elsewhere in the universe [1].…”