Oct 3, 2020 11:41 PM
INTRO: Welcome to our Fermi Paradox series, where we take a look at possible resolutions to Enrico Fermi’s famous question, “Where Is Everybody?"
We'll find E.T. with a molecule, not a message
https://astronomy.com/news/2020/10/well-...-a-message
INTRO (excerpts): Life on Venus? That outrageous-sounding possibility understandably made headlines a couple weeks ago. In part, the news grabbed people's attention because Venus seems like such an unlikely place to find anything alive. The surface temperature there averages 460 degrees Celsius, and the pressure at sea level is a crushing 93 times the atmospheric pressure on Earth — except, of course, there is no actual sea on Venus.
There was another startling aspect of the life-on-Venus story, however: the nature of the evidence itself. [...] Those provocative hints of life came in the form of an extremely slight radio shadow indicating the presence of a molecule known as phosphine, a phosphorus atom bonded to three hydrogen atoms. ... The discovery of phosphine on Venus was an unexpected, confoundingly obscure signal of potential alien life. It was also a telling preview of things to come.
As scientists expand their search for life across the solar system, and on planets orbiting other stars, there will be more and more reports of possible life detections. As with phosphine on Venus, they will come from indirect data. They will be ambiguous. They will be fiercely debated. And those signals of alien life will all, with near-certainty, take the form of a molecule.
Astrobiologists call any detectable evidence that life is present now, or that it was present in the past a "biosignature." In principle, a biosignature could come in the form of a flying saucer with aliens parading down a set of impeccable white stairs, or of a radio signal containing instructions on how to build an interstellar gateway. I can't say that these things are impossible. Nobody can. But the overwhelming likelihood is that the first indications of alien life will take the form of molecules like phosphine — molecules that are commonly associated with biological processes, and that seem difficult to explain without them.
If you are a skeptical reader (and I hope you are!) you might well ask at this point, "How can you know?" Since we have no idea what kind of life, if any, exists in the universe beyond Earth, how can we possibly claim to know what kinds of detections are more likely than others? Fortunately, we're not flying completely blind here. We can take some important lessons from our technological limitations, from the nature of life on Earth, and from some of the fundamental physical principles that limit what life can do... (MORE - details)
- Beyond “Fermi’s Paradox” I: A Lunchtime Conversation- Enrico Fermi and Extraterrestrial Intelligence
- Beyond “Fermi’s Paradox” II: Questioning the Hart-Tipler Conjecture
- Beyond “Fermi’s Paradox” III: What is the Great Filter?
- Beyond “Fermi’s Paradox” IV: What is the Rare Earth Hypothesis?
- Beyond “Fermi’s Paradox” V: What is the Aestivation Hypothesis?
- Beyond “Fermi’s Paradox” VI: What is the Berserker Hypothesis?
- Beyond “Fermi’s Paradox” VII: What is the Planetarium Hypothesis?
- Beyond “Fermi’s Paradox” VIII: What is the Zoo Hypothesis?
- Beyond “Fermi’s Paradox” IX: What is the Brief Window Hypothesis?
- Beyond “Fermi’s Paradox” X: What is the Firstborn Hypothesis?
- Beyond “Fermi’s Paradox” XI: The Transcension Hypothesis
We'll find E.T. with a molecule, not a message
https://astronomy.com/news/2020/10/well-...-a-message
INTRO (excerpts): Life on Venus? That outrageous-sounding possibility understandably made headlines a couple weeks ago. In part, the news grabbed people's attention because Venus seems like such an unlikely place to find anything alive. The surface temperature there averages 460 degrees Celsius, and the pressure at sea level is a crushing 93 times the atmospheric pressure on Earth — except, of course, there is no actual sea on Venus.
There was another startling aspect of the life-on-Venus story, however: the nature of the evidence itself. [...] Those provocative hints of life came in the form of an extremely slight radio shadow indicating the presence of a molecule known as phosphine, a phosphorus atom bonded to three hydrogen atoms. ... The discovery of phosphine on Venus was an unexpected, confoundingly obscure signal of potential alien life. It was also a telling preview of things to come.
As scientists expand their search for life across the solar system, and on planets orbiting other stars, there will be more and more reports of possible life detections. As with phosphine on Venus, they will come from indirect data. They will be ambiguous. They will be fiercely debated. And those signals of alien life will all, with near-certainty, take the form of a molecule.
Astrobiologists call any detectable evidence that life is present now, or that it was present in the past a "biosignature." In principle, a biosignature could come in the form of a flying saucer with aliens parading down a set of impeccable white stairs, or of a radio signal containing instructions on how to build an interstellar gateway. I can't say that these things are impossible. Nobody can. But the overwhelming likelihood is that the first indications of alien life will take the form of molecules like phosphine — molecules that are commonly associated with biological processes, and that seem difficult to explain without them.
If you are a skeptical reader (and I hope you are!) you might well ask at this point, "How can you know?" Since we have no idea what kind of life, if any, exists in the universe beyond Earth, how can we possibly claim to know what kinds of detections are more likely than others? Fortunately, we're not flying completely blind here. We can take some important lessons from our technological limitations, from the nature of life on Earth, and from some of the fundamental physical principles that limit what life can do... (MORE - details)