How Far Human Civilisation is Detectable in Space
Earth’s most detectable techno-signatures are the planetary radar transmissions from the erstwhile Arecibo Observatory............
#Arecibomessage #AreciboObservatory #ETI #ExtraTerrestrial #Extraterrestrialintelligence #SETI
Umesh Prasad
#ExtraterrestrialIntelligence
How Far Human Civilisation is Detectable in Space
Earth’s most detectable techno-signatures are the planetary radar transmissions from the erstwhile Arecibo Observatory............
#Arecibomessage #AreciboObservatory #ETI #ExtraTerrestrial #Extraterrestrialintelligence #SETI
Umesh Prasad
How Far Human Civilisation is Detectable in Space
Earth’s most detectable techno-signatures are the planetary radar transmissions from the erstwhile Arecibo Observatory............
#Arecibomessage #AreciboObservatory #ETI #ExtraTerrestrial #Extraterrestrialintelligence #SETI
Umesh Prasad
Where are the aliens?
Among my earliest memories are the TV series Star Trek and Lost in Space, two shows that promised a universe teeming with alien life, intelligent life. As a boy, the aliens seemed everywhere. We’d probably find some on Mars and Venus, and there wasn’t much doubt we’d find them in other solar systems. And that was assuming they weren’t already visiting us and picking up people on lonely country roads or pilots in the Bermuda Triangle.
I gradually became disillusioned about all these possibilities. UFOs (now UAPs) gradually turned out to be mundane phenomena, or military aircraft of some type. Mars was pretty much verified dead, or at least mostly dead, by the time I was ten. And Venus turned out to be hell. For a while the idea of interstellar aliens held out as a possibility, until I learned about Fermi and his paradox.
Physicist Enrico Fermi, at a lunch in 1950, after a discussion about how life should be prevalent in the universe, asked, “Where is everybody?” (Or something similar, accounts vary.) If intelligent life is everywhere, then Earth should have been visited and colonized long ago, certainly long before humans evolved. Yet we have no evidence anything like this has ever happened.
The Fermi Paradox has long struck me as a serious problem for the idea of pervasive alien civilizations. It also seems to fit with a couple of observations about our own planet. Of the billions of species that have ever existed, only one ever evolved enough intelligence to build a civilization, at least that we know of. From this, it seems reasonable to assume that, alien life may or may not be common, but alien civilizations may be profoundly rare. So rare that our nearest neighbors are too distant to have reached us yet.
But there are those who push back against this conclusion. One of them is astronomer Adam Frank, as he did in a recent interview with Lex Fridman. Frank argues that if aliens visited us in the deep past, say hundreds of millions of years ago, we wouldn’t be able to find evidence of it. The fossil evidence is sparse, and Earth’s surface, due to ongoing volcanic and tectonic processes, is constantly being replaced.
Along similar lines, Frank is one of the authors who put forth the Silurian Hypothesis, the idea that if there had been an intelligent species in Earth’s remote past, say 100 million years ago, who managed to create an industrial civilization, we’d have a hard time finding evidence for it.
Although given the effects humanity is having today, I’m not sure how much I buy this. It seems like a civilization with widespread metallurgy, plastics, fossil fuel depletion, nuclear power, and other activities would leave marks in the geological record. And when exploring the details, Frank admits this, along with noting that we could also find evidence on the moon or Mars, both of which have been scanned from orbit pretty thoroughly at this point.
But it is definitely true that if an alien civilization visited Earth in the remote past without settling the entire planet, then we wouldn’t be able to find evidence for it. We can only say they’re not here now, or at least not in any manner that we can detect. It also still leaves our nearest neighbors distant, just in time instead of necessarily in space. It’s also a pretty dark hypothesis if you think about it, because it implies that what we’ll find in the galaxy is a graveyard of past civilizations. And that all civilizations fail to survive in the long run, since it would only take one for them to still be here.
Frank also, with other authors in a recent paper, attacks the idea of intelligence being rare. They focus on the “Hard Steps model” put forth by Dan Mills, the idea that our evolution required a number of highly improbable steps: abiogenesis, photosynthesis, eukaryotic life, sexual reproduction, multicellular life, etc. If so, then our evolution looks like a profoundly improbable event, and we might be alone in the observable universe.
The arguments against this model note that these steps may only look improbable. What looks like singular evolutionary events to us may be because all of the alternate competing versions went extinct. It’s also possible that once a certain ecological niche gets filled, the ability of any other species to evolve into it becomes blocked, since any newcomers won’t have time to become established before losing in competition to the already well established dominant species. That and life sometimes “pulls the ladder up behind it”, such as the oxygenation of the atmosphere from photosynthetic organisms removing the early conditions on Earth that allowed life to begin in the first place.
And the authors point out that many of the evolutionary events required environmental changes before they could take place. For example, animals require significant oxygen levels in the atmosphere to power their bodies.
Estimated evolution of atmospheric oxygen. Image credit.When we ask why the animals evolved when they did, at least part of the answer was the increasing oxygen levels on the planet. It’s possible that some of these developments might have happened sooner if the conditions had arisen earlier. Although in many cases, oxygen being the key example, it was life itself which created the conditions.
The authors also question how unique humans really are. They argue that there are no categorical differences between us and other species. Capabilities which we once took to be unique to humans, such as tool use and problem solving, have been shown to exist in many other species. Although I think they may overlook the significance of symbolic thought (language, math, etc).
Quibbles aside, I think these arguments do weaken the Hard Steps model, and the idea that humans are unique in the overall universe. But I don’t know that it serves as an answer to Fermi’s original question. If intelligence is everywhere, then where is everybody?
Another possibility not often discussed is that maybe interstellar travel is impossible, or so monstrously difficult that no one bothers. The engineering difficulties are profound. Maybe, despite all the idea tossed around, none will bear fruit. It seems difficult to imagine we won’t be able to find some way to at least send uncrewed probes, but until we succeed in landing a functioning probe on a planet around another star, we won’t know for sure.
If so, then the only hope of contact might be through communications, but it would likely be conversations held across centuries or millenia. If we become a long lived species, or can find ways to upload and transmit our minds, maybe that would be enough. But it’s still pretty far from the Star Trek type universe.
But maybe I’m missing something. Are there reasons for optimism about alien intelligences that I’m overlooking? Or is the situation as bleak as Dan Mills originally saw it, and we’re just fooling ourselves?
#Aliens #extraterrestrialCivilizations #extraterrestrialIntelligence #Science
…❛❛ In 1971, dozens of #astronomers & #astrophysicists convened in a conference room at the Byurakan Astrophysical Observatory in #Armenia for the 1st joint #American & #Soviet conference on communicating with #ExtraterrestrialIntelligence. American & Soviet scientists had met independently to discuss the topic in the early 1960s ❜❜…
🔗 https://www.thriftbooks.com/w/extraterrestrial-languages_daniel-oberhaus/20885525/
🔗 https://Wikipedia.org/wiki/Active_SETI
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https://newspaceeconomy.ca/2024/04/13/the-great-silence-the-perplexing-absence-of-extraterrestrial-life/
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https://newspaceeconomy.ca/2024/04/10/unidentified-aerial-phenomena-the-australian-governments-perspective/
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https://newspaceeconomy.ca/2024/04/08/is-your-religion-ready-to-meet-et/
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AI is helping astronomers make new discoveries and learn about the universe faster than ever before
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https://newspaceeconomy.ca/2024/03/18/ai-is-helping-astronomers-make-new-discoveries-and-learn-about-the-universe-faster-than-ever-before/
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