27 April 2024

Data from exoplanet research points to a "rare earth" conclusion

I know I harp on this a lot, but it amuses me and I honestly believe this kind of "cosmic view" of our planetary predicament is not only a good thing, it is vital to our ability to understand our problems and devise strategies to actually solve them sustainably. If it doesn't interest you, the delete button is on the upper right and no need to belabor the point.  

I asked ChatGPT this: 

Would it be accurate to say that exoplanet data has led to the conclusion that planets, and planetary systems, are more variable, and thus less like the Solar System, in general and on average, than had previously been thought? And, therefore, that planets closely resembling Earth, with large liquid water oceans, plate tectonics, and at least the potential for the continued existence of carbon based life over very long periods of time, need to be considered quite rare in the population of disk stars, many of which in other respects may closely resemble the Sun?
And ChatGPT answered thus:

Yes, it would be accurate to make such a statement. Observations of exoplanets have indeed shown that planetary systems exhibit a remarkable diversity, much greater than what was anticipated based on our Solar System alone. Many exoplanets discovered do not fit into the neat categories previously envisaged from our Solar System's structure. For instance, the discovery of "hot Jupiters" (gas giants that orbit very close to their stars) and "super Earths" (rocky planets larger than Earth but smaller than Neptune) challenged our conventional understanding of planetary system formation.

These findings imply that systems similar to our Solar System might be less common than once thought. When it comes to Earth-like planets, while many have been found in the habitable zone (where conditions could potentially allow liquid water to exist), the additional conditions necessary for Earth-like life—such as significant liquid water oceans, plate tectonics, and a stable climate system—are not easily inferred from distance observations alone. These factors contribute to the complex environments needed for life as we know it, suggesting that truly Earth-like planets could indeed be rare among the vast array of planetary systems.

Thus, the growing catalog of exoplanet characteristics has indeed led to a broader understanding that while star-like our Sun may be common, planets with conditions similar to Earth might be much rarer in the universe. This adds an important perspective to our search for extraterrestrial life and the study of planetary habitability.

Caveat: ChatGPT is, I've observed, somewhat susceptible to "leading questions," of which this might be considered an ultimate example.  ChatGPT lacks consciousness, which, unfortunately, means that to a considerable extent it lacks what you might call judgment, or discretion. Still, I think the answer is pretty consistent with the published information. It really is true that up until around 2000 it was generally thought that the Solar System, with its four inner "rocky" and four outer "gas" planets, was typical, but, well, it just isn't, as we now know, from well over 1500 fairly well defined example systems. And planets even within these categories (plus the entirely missing here category of "Super Earth") -- vary enormously, and, usually, not in a way conducive to the abiogenetic origin and persistence of carbon based life for long time periods. A lot of things have to go right, in a universe where "going wrong" is the norm (2d Law of Thermodynamics). 

I regard as a wake-up call the likelihood that life, and especially complex life, and even more especially intelligent life (whatever that loaded term may mean in the real world)... all are somewhere in the range of rare to exceedingly rare. The Copernican worldview, also known as the Principle of Mediocrity, while useful to science in many regards, cannot be taken too literally. In truth, the Sun is an unusually large and bright star (~90+ percentile). And the Earth is an extraordinarily rare and precious instance of a "bio-available" planet. My best guess is that fewer than 1 in 100,000 star systems have a planet that could be said to "closely" resemble Earth, even limiting consideration to merely physical and chemical similarities, without including the actual existence of complex life. Which may and probably will turn out to be another stringent limiting factor. I think it likely that fewer than 1 in a million or even 10 million star systems harbors a planet that could be considered closely comparable to Earth, and far fewer even than that that actually harbor intelligent living beings comparable to ourselves at the present epoch. Indeed, there are reasons to suppose it is unlikely that there is even one other such "currently inhabited by an intelligent species" world in this Galaxy. 

I feel we need to remind ourselves: We toy with the potential collapse of Earth's biosphere systems at our gravest peril. Literally everything we care about or have ever cared about is at stake, and science is telling us that we cannot take it for granted. Because for all intents and purposes there is only one Earth, and we will not find any solution to our problems of learning to live sustainably by expecting to find other worlds to just move to at some distant future date. That may eventually even happen, but not until and unless we figure out how to maintain our civilization with only the one world.  


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