There is no ET - per Anders Sandberg et al

[jim mcnamara]

Can anyone find an actual paper? I cannot.

This is an un-refereed citation, more like a slide show for a talk:
"Dissolving the Fermi Paradox"
Anders Sandberg, Eric Drexler, Tony Ord
http://www.jodrellbank.manchester.ac.uk/media/eps/jodrell-bank-centre-for-astrophysics/news-and-events/2017/uksrn-slides/Anders-Sandberg---Dissolving-Fermi-Paradox-UKSRN.pdfPlease try reading some of the pdf first. An easy read, without a lot of discussion.

One of the claims: abiogenesis could easily be common, but getting from the start to DNA is likely not happen fast enough, so 'the clock runs out' and the environment changes to the point where nothing can survive. Like what our own G star will do to Earth, circa 5 billion years in the future. For Earth to get to the point of intelligent life took a substantial chunk of time. 4 billion years.

 

[BillTre]

Here is a link to an arxiv posting, where you can download a different pdf.
It says it will be: "Submitted to Proceedings of the Royal Society of London A; 4 supplements".

 

[russ_watters]

Please try reading some of the pdf first. An easy read, without a lot of discussion.

I'll admit to only having skimmed the PDF, but I don't consider the Fermi paradox to be much of a paradox either, and isn't odd, but for a different reason from the PDF: space is big. The wiki article on it points out that even at speeds we could achieve, we could traverse the galaxy in a few million years. So? Even if we could build a ship capable of it, why would we? Why would anyone else? Even if we could prove there was life in a nearby star system (and I believe we will in my lifetime), why would we bother sending a mission to explore it that would take ten thousand generations (a hundred times the age of the human race) to get there? That we don't observe other civilizations could simply because we are far away.

One of the claims: abiogenesis could easily be common, but getting from the start to DNA is likely not happen fast enough, so 'the clock runs out' and the environment changes to the point where nothing can survive. Like what our own G star will do to Earth, circa 5 billion years in the future. For Earth to get to the point of intelligent life took a substantial chunk of time. 4 billion years.

I don't consider 45% to be a problematic fraction of lifespan, particular considering *my* age. If we were at 8 billion, 900 million years into the Sun's life and humans evolved while the sun was expanding to to consume Earth, I'd consider that a small window.

Few if any of the specifics of Earth's specifications seem unusually rare*. We're in a good spot in the habitable zone, Earth is middle-aged, we have a Jupiter to clear-out asteroids from the inner solar system, etc. All of these things seem to me as about as mundane as running into your neighbor at the grocery store. They seem like more of an inevitable outcome than a spectacularly rare confluence of extraordinarily rare events to me.

*The most unusual to me would be the asteroid that killed the dinosaurs. This event took an apparently stable biosphere and shook it up in a way that enabled us to emerge. But even then, massive extinction events aren't that rare either.

 

[BillTre]

I also am somewhat skeptical of this approach.
WRT the parts about the likelihood of chemistry generating "life", it seems like a lot of numbers being intuited, without a lot of experimental support.
This stuff is not yet well understood.

Another thing is what I consider the sloppiness of word usage in many discussions of this field.
The terms "life" and "intelligent life" are often used without clear distinctions.
The "having life" condition would be fulfilled by just having bacteria/archaeal level organisms, something that seems to have happened quite rapidly on earth.
This pdf is about having intelligent life, but in some places they just say life. Not good, as it can lead to confusion.

Intelligent life on Earth required the evolution of eukaryotic life forms, with their access to greater energy sources than that of mere bacteria (and archaea).
This allowed the production of much greater complexity of cellular form and in multi-cellular organisms larger and more complex organisms that are able to support a nervous system that would be able to underlie "intelligent" behavior. Bacteria/Archaea have never done this in their 3 billion years here.
The jump from the bacterial/archaeal grade of organism organization (generation of mitochondria from a bacterial symbiont in an archaeal cell) took about 1-2 Billion years after the bacterial/archaeal arose. A significant delay, based upon an unlikely and difficult relationship to set up.

After the eukaryotes arose it only took another ~1billion years to make the human lineage (which is common referred to as "intelligent").
Intelligence is another poorly defined term. In this usage, it seems to really mean; intelligent in a Fermian manner (as in having a big enough effect to make astronomical observations possible)
Alternatively, some argue that crows are intelligent.
The human lineage itself has generated several different most likely intelligent species (Neanderthals, Denisovans, etc.). This affect the likelihood of intelligent life generation as I look at it has greater than one on just our single planet.
The level of "intelligence", to be noticed cosmologically, would require the development of a well organized and large social structure.
This is something beyond mere intelligence in creatures and should be distinguished from it.
I do think the Drake equation makes a lot of these distinctions, but the way people talk about it breezes over those issues.

This is my rant about sloppy word use in very complex issues. Sloppy word use doesn't help bring clarity.

 

[jim mcnamara]

@BillTre did you read the very first page? And what is the name of the institute? A tad woo-woo IMO. Anyway I wanted this up to fend off some of the potential takes on the pop-sci "news" sites.

@russ_watters , @BillTre - Anyway good posts guys. I think the entire concept needs a tune up, but this um, "thing", probably is not it. But it is worthy of discussion.

 

[BillTre]

New @BillTre did you read the very first page? And what is the name of the institute? A tad woo-woo IMO. Anyway I wanted this up to fend off some of the potential takes on the pop-sci "news" sites.

Here is what the second pdf has:
Anders Sandberg, Eric Drexler and Toby Ord Future of Humanity Institute, Oxford University

 

[lpetrich]

Here's what the authors did. They collected estimates from the literature, then fit probability distributions to them. They then found the overall probability distribution of N, the number of communicative technical civilizations. It has a probability of 30% of being less than one per Milky-Way-sized galaxy and 10% of being less than one per observable Universe.

When the Drake equation was proposed, back in 1961, the only parameter that we had any clue about was Rs, the rate of star formation. Nowadays, we have a good clue as to fp and we are starting to get one about ne. We still don't have much of a clue about fl, fi, fc, or L, however.