In my last post, I reviewed the standard theory that life on Earth got very lucky to complete a series of hard try-try steps to get to our human level before its window for life closes. I said that this theory has had only
Accepting the premise of Eden for now, it seems Eden must be much older than Earth, i.e., it could not have been part of the solar system's birth cluster, so it must have passed by the cluster by chance when it "infected" the newly-formed planets in it (Earth among them) with life. Its easy to infect many planets at once this way, compared to distant encounters with field stars (i.e., away from clusters), especially if interstellar travel times of living microorganisms are strongly limited. This suggests life is likely to appear early on an infected planet as its easy to get infected early on (as part of a cluster), and difficult to get infected later (outside cluster). Most civilizations on infected planets would thus observe that life on their planet started early (i.e., in the birth cluster).
We might never find Eden, but we could test the above scenario if planets with life-signs (which we are bound to find sooner or later) turn out to all have the same age as the Earth, or a set of discreet ages, one of which matches the age of the Earth. This would allow us to estimate how many clusters have been infected by Eden, and over what time interval it was spreading lifeforms (perhaps, up to the present day?).
Star Trek lore is that millions of years ago there existed a humanoid species that waged war on the other then-existing non-humanoid species on the galaxy. It won, spread its own genetic code around, then eventually went away or went extinct. As a result, most intelligent life nowadays are both humanoid and related, with very few non-humanoid intelligent species having survived (or evolved since then).
One possible candidate for that species would be the Q, who are in the habit of judging and, if finding them wanting, extinguishing entire intelligent species. They're presumably responsible for the two mega-structures that form the two energy barriers surrounding, one, the galaxy as a whole, the other, the galactic core. The resulting toroid where most characters in the series live, Earth included, is the Q's playground to do with whatever they want for whatever purpose they may have. Including, it seems, keeping the different humanoid species capable of interbreeding.
So, both more coherent than usually given credit for, while also orders of magnitude less plausible.
"Genetic Takeover" is mostly focused on a clay-mineral -> carbon takeover. Clays self-assemble into aperiodic crystalline structures. Most carbon-based systems instead form sticky tars. Carbon componds are more stable and flexible in the long term, but they don't self-assemble so well - ultimately due to the strong carbon bonds. Many silicon-based structures are less stable and shake themselves to pieces more easily - but the flip side is that their more-reversible interactions mean that they self-assemble better too. It turns out that is just what is needed for the first genomes. Crystal growth processes come with their own natural error correction. Silicon-based crystals are common - carbon-based crystals are rare - and instead you typically get tars.
The possibility of genetic takeovers mean that we don't need to confine our early ancestor search to systems that resemble current biochem. Instead we can look for what is pre-biotically plausible. It is a whole different ball game. Current biochem systems are very advanced. Early systems could have been quite different.
Most takeover scenarios maintain carbon and water at all stages. So yes some changes are possible, but even so knowing that it must lead to our sort of life is surely a big clue to what Eden was made of.
I assume Star Trek is a series predicated on the existence of Eden; many similarly evolved humanoids, who are even capable of procreation with one another. Helps make that show (a little) more coherent.
There's no rule saying that simple life is possible. Maybe, below a certain level of complexity, all possible creatures tend to disintegrate. If so, the apparent jump to early organisms has to be crossed by chance. It doesn't matter if the probability is small: the multiverse is big, it only had to happen once, and we know that it did happen. In that scenario, no urgent need to search for eden - the inference that eden exists would just be mistaken.
Re: "Eventually, Eden would have been home to the sort of life that gave rise to Earth’s sort of life. With carbon, water, and DNA. So that rejects exotic hypothesized life such as made of silicon".
That is not correct because of the possibility of genetic takeovers. E.g. see "Genetic Takeover" by A. G. Cairns-Smith - or one of the popularizations of the idea.
Seems very much good enough. The breadth and depth on topics you have valuable insight on is easily lost admist the incessant flow of productivity on the topics you happen to be interested in right now - which gives an AMA post its own niche (topics besides those you decide to write explicitly about).
Yes, also different characteristics on different planets (radiation, climate, water levels) might help because one try-try level might be easier to achieve on one planet and another level on another planet.
Oh, you are thinking that by being near each other and having panspermia between, they become equivalent to one larger planet? That's a good point, which I'll add to the post.
Very insightful. A series of nearby planets would also reduce risk of life dying of.
Yes, one plausible idea is that Eden seeded the sun's nursery, and thus many of the sun's siblings at the same time.
Accepting the premise of Eden for now, it seems Eden must be much older than Earth, i.e., it could not have been part of the solar system's birth cluster, so it must have passed by the cluster by chance when it "infected" the newly-formed planets in it (Earth among them) with life. Its easy to infect many planets at once this way, compared to distant encounters with field stars (i.e., away from clusters), especially if interstellar travel times of living microorganisms are strongly limited. This suggests life is likely to appear early on an infected planet as its easy to get infected early on (as part of a cluster), and difficult to get infected later (outside cluster). Most civilizations on infected planets would thus observe that life on their planet started early (i.e., in the birth cluster).
We might never find Eden, but we could test the above scenario if planets with life-signs (which we are bound to find sooner or later) turn out to all have the same age as the Earth, or a set of discreet ages, one of which matches the age of the Earth. This would allow us to estimate how many clusters have been infected by Eden, and over what time interval it was spreading lifeforms (perhaps, up to the present day?).
Star Trek lore is that millions of years ago there existed a humanoid species that waged war on the other then-existing non-humanoid species on the galaxy. It won, spread its own genetic code around, then eventually went away or went extinct. As a result, most intelligent life nowadays are both humanoid and related, with very few non-humanoid intelligent species having survived (or evolved since then).
One possible candidate for that species would be the Q, who are in the habit of judging and, if finding them wanting, extinguishing entire intelligent species. They're presumably responsible for the two mega-structures that form the two energy barriers surrounding, one, the galaxy as a whole, the other, the galactic core. The resulting toroid where most characters in the series live, Earth included, is the Q's playground to do with whatever they want for whatever purpose they may have. Including, it seems, keeping the different humanoid species capable of interbreeding.
So, both more coherent than usually given credit for, while also orders of magnitude less plausible.
"Genetic Takeover" is mostly focused on a clay-mineral -> carbon takeover. Clays self-assemble into aperiodic crystalline structures. Most carbon-based systems instead form sticky tars. Carbon componds are more stable and flexible in the long term, but they don't self-assemble so well - ultimately due to the strong carbon bonds. Many silicon-based structures are less stable and shake themselves to pieces more easily - but the flip side is that their more-reversible interactions mean that they self-assemble better too. It turns out that is just what is needed for the first genomes. Crystal growth processes come with their own natural error correction. Silicon-based crystals are common - carbon-based crystals are rare - and instead you typically get tars.
The possibility of genetic takeovers mean that we don't need to confine our early ancestor search to systems that resemble current biochem. Instead we can look for what is pre-biotically plausible. It is a whole different ball game. Current biochem systems are very advanced. Early systems could have been quite different.
I'm happy to rely on a better time series if available. But until I'm offered an alternative, I'll judge based on what I have.
Most takeover scenarios maintain carbon and water at all stages. So yes some changes are possible, but even so knowing that it must lead to our sort of life is surely a big clue to what Eden was made of.
Having Eden spread a common humanoid life across the sibling stars seems inconsistent with the actual history of life on Earth.
I assume Star Trek is a series predicated on the existence of Eden; many similarly evolved humanoids, who are even capable of procreation with one another. Helps make that show (a little) more coherent.
There's no rule saying that simple life is possible. Maybe, below a certain level of complexity, all possible creatures tend to disintegrate. If so, the apparent jump to early organisms has to be crossed by chance. It doesn't matter if the probability is small: the multiverse is big, it only had to happen once, and we know that it did happen. In that scenario, no urgent need to search for eden - the inference that eden exists would just be mistaken.
Re: "Eventually, Eden would have been home to the sort of life that gave rise to Earth’s sort of life. With carbon, water, and DNA. So that rejects exotic hypothesized life such as made of silicon".
That is not correct because of the possibility of genetic takeovers. E.g. see "Genetic Takeover" by A. G. Cairns-Smith - or one of the popularizations of the idea.
Seems very much good enough. The breadth and depth on topics you have valuable insight on is easily lost admist the incessant flow of productivity on the topics you happen to be interested in right now - which gives an AMA post its own niche (topics besides those you decide to write explicitly about).
Also, it would be good fan service.
Makes sense.
The Sharov graph is interesting, but I wonder how robust its estimated points are.
First, what do we really know about the genome sizes of early prokaryotes and eukaryotes respectively?
They can vary hugely in size:https://en.wikipedia.org/wi...https://www.ncbi.nlm.nih.go...
How do we know that the earliest ones weren't extreme outliers in terms of their number of base pairs? Isn't this what we should expect?
A possibly relevant paper on the evolution of genome size in prokaryotes:https://www.ncbi.nlm.nih.go...
Yes, also different characteristics on different planets (radiation, climate, water levels) might help because one try-try level might be easier to achieve on one planet and another level on another planet.
Oh, you are thinking that by being near each other and having panspermia between, they become equivalent to one larger planet? That's a good point, which I'll add to the post.