Origin of Life

Cypress said:
I currently lean towards number two, but keep an open mind.
It would be nice if we had more intel on emergence: the transition from non-life to life. There is zero chance something as mind boggling complex as even a single eukaryotic cell just appeared on the scene without an incredible sequence of interim events. Unless we were seeded from another planetary body.
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No #4?
 
Quote Originally Posted by Dutch Uncle View Post
Evidence currently states life only evolved on Earth.
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incorrectly stated......the fact that we only have evidence of life on earth leads to no conclusions at all that it is the only place where there is life......it merely shows that its the only place where we evidence of it.......
 
Cypress said:
Not a bad point, but the caveat is that only hydrogen and helium condensed from the big bang. Carbon, phosphorus, nitrogen, and associated organic compounds ultimately were manufactured in super novas.

The problem is not with the building blocks of life - organic compounds are ubiquitous in the universe. The challenge is how did these molecules assemble themselves into exceedingly complex, self-replicating cells. Even after 70 years of intensive study, it remains a mystery.
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Supernovae are not uncommon so we're back to nothing unusual about Earth. I understand your question but I've also read through the rest of the thread and there are a couple of points that I have some thoughts on.

1) Why has life not re-emerged?

I'm not a super-scientist but my guess is that the conditions necessary for the emergence of life are not the same as the conditions necessary for the flourishing of life...IOW the emergence of life guarantees life won't emerge again.

2) It took 4 billion years for advanced life to come to be.

We actually don't know this to be true. Anything older than 18,000 years is most likely under about 600 feet of water so there's a lot we don't know about our past. We do not have eyes to see.

Another question, and a good one, is how did intelligent life evolve at all? I don't know, but it did and I doubt that is unique because if it happened once it assuredly happened more than once, perhaps not on Earth but the Universe is a big sandbox.
 
cordeela said:
Is "4 billion" just a marker of scale or do they literally mean 4 Billion year ago??
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Are you talking about the beginnings of life on Earth? That would be literally approximately four billion years ago; the planet itself is approx. 5 billion years old.
 
Guille said:
Supernovae are not uncommon so we're back to nothing unusual about Earth. I understand your question but I've also read through the rest of the thread and there are a couple of points that I have some thoughts on.

1) Why has life not re-emerged?

I'm not a super-scientist but my guess is that the conditions necessary for the emergence of life are not the same as the conditions necessary for the flourishing of life...IOW the emergence of life guarantees life won't emerge again.

2) It took 4 billion years for advanced life to come to be.

We actually don't know this to be true. Anything older than 18,000 years is most likely under about 600 feet of water so there's a lot we don't know about our past. We do not have eyes to see.

Another question, and a good one, is how did intelligent life evolve at all? I don't know, but it did and I doubt that is unique because if it happened once it assuredly happened more than once, perhaps not on Earth but the Universe is a big sandbox.
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That is the 64,000 dollar question: is the emergence ofnlife exceedingly rare, and necessitates a highly improbable series of chemical and physical reactions? Or do chemistry and physics inevitably lead to the emergence of life given favorable environmental conditions?

It is established fact that the earth is older than four billion years, based on radiometric dating of continental rocks and meteorites.

It is known with a high degree of confidence that microbial life emerged 3.5 to 3.8 billion years ago, based on microfossils and isotopic biosignatures in Archean rocks of Greenland and Australia

I agree and hope that there could be life beyond earth. But I am dubious that is is ubiquitous. I lean towards it being fairly rare.
 
domer76 said:
Yep. At one time, the facts were that we were also the center of the universe. Sounds similar.
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Those were observations, not facts. It wasn't a "fact" that the Earth was flat but some people thought it was flat. Not all. Many ancient peoples understood that the world might be round such as observing the north star sink below the northern horizon when heading south, the round shadow on the Moon during a Lunar eclipse and that two sticks of the same length above the ground cast slightly different shadows at noon when they were several miles North-South of each other.

The fact is that, despite decades of searching, we've yet to find signs of life anywhere in the Universe, much less our own Solar System.

That said, "An absence of evidence isn't evidence of absence".
 
PostmodernProphet said:
incorrectly stated......the fact that we only have evidence of life on earth leads to no conclusions at all that it is the only place where there is life......it merely shows that its the only place where we evidence of it.......
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Only idiots conclude such a thing. The fact remains Earth is the only place with evidence of life. No projections please.
 
Dutch Uncle said:
The facts speak for themselves: There is no proof of life in the Universe except on Earth. :)
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that is why I am one of the few on the thread to suggest life in the galaxy might be rare; I am erring on the side of caution, and recognizing that the jump from organic molecules to complex, self-replicating microbes was a one-time event on Earth in its 4.5 billion year history.

Lacking the ability for interstellar travel, our best bet may be to look for biosignatures in the atmospheres of Earth-like exoplanets, like free oxygen.. We should have that capability in the next decade.

I am not ruling out extinct or current microbial life on Mars, the moons of Saturn and Jupiter. I am just not going to get my hopes up too high
 
Cypress said:
that is why I am one of the few on the thread to suggest life in the galaxy might be rare; I am erring on the side of caution, and recognizing that the jump from organic molecules to complex, self-replicating microbes was a one-time event on Earth in its 4.5 billion year history.

Lacking the ability for interstellar travel, our best bet may be to look for biosignatures in the atmospheres of Earth-like exoplanets, like free oxygen.. We should have that capability in the next decade.

I am not ruling out extinct or current microbial life on Mars, the moons of Saturn and Jupiter. I am just not going to get my hopes up too high
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Agreed life is likely out there but for some reason it's very difficult to find. If it was abundant, we should have found some indications of life elsewhere.

That's one of the main missions of Perseverance: to continue looking for life.

https://mars.nasa.gov/mars-exploration/missions/mars2020/
The mission addresses high-priority science goals for Mars exploration, including key questions about the potential for life on Mars. Perseverance takes the next step by not only seeking signs of habitable conditions on Mars in the ancient past, but also searching for signs of past microbial life itself.
 
Dutch Uncle said:
Those were observations, not facts. It wasn't a "fact" that the Earth was flat but some people thought it was flat. Not all. Many ancient peoples understood that the world might be round such as observing the north star sink below the northern horizon when heading south, the round shadow on the Moon during a Lunar eclipse and that two sticks of the same length above the ground cast slightly different shadows at noon when they were several miles North-South of each other.

The fact is that, despite decades of searching, we've yet to find signs of life anywhere in the Universe, much less our own Solar System.

That said, "An absence of evidence isn't evidence of absence".
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Sure, we can play that game. There is no observation of extraterrestrial life.
 
Dutch Uncle said:
Agreed life is likely out there but for some reason it's very difficult to find. If it was abundant, we should have found some indications of life elsewhere.

That's one of the main missions of Perseverance: to continue looking for life.

https://mars.nasa.gov/mars-exploration/missions/mars2020/
The mission addresses high-priority science goals for Mars exploration, including key questions about the potential for life on Mars. Perseverance takes the next step by not only seeking signs of habitable conditions on Mars in the ancient past, but also searching for signs of past microbial life itself.
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your a moron dutch a real moron you know that. we have not ventured past them moon with a manned space mission. the nearest star to us that could have life is over 4 light years away and there are billions of stars alone in the milky way and billions of galaxy's in the universe .We can only see a bit over 13 billion light years away . No one reallyu knows how big the universe is.


Your assuming that intelligent life uses the same method of communication as we do it could take billions of years for a civilization to even receive a message from up or send one to use even if we used the same forms of communication.

Other civilizations capable of it could of died off billions of years ago or still be developing to reach that level..
we have only had the ability to send radio waves into space for a blink of a eye time wise .

you seem to have comprehension of the time and distances and technology involved , typical democrat.
 
Dutch Uncle said:
Agreed life is likely out there but for some reason it's very difficult to find. If it was abundant, we should have found some indications of life elsewhere.

That's one of the main missions of Perseverance: to continue looking for life.

https://mars.nasa.gov/mars-exploration/missions/mars2020/
The mission addresses high-priority science goals for Mars exploration, including key questions about the potential for life on Mars. Perseverance takes the next step by not only seeking signs of habitable conditions on Mars in the ancient past, but also searching for signs of past microbial life itself.
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A good insight, but to be fair, we have only looked for life in an infinitesimally small part of the galaxy: one planet besides earth in our solar system, and SETI has only looked at the electromagnetic radio wave signatures of only fraction of nearby star systems. There are hundreds of billions of star systems in the milky way, and hundreds of trillions of stars in the observable universe.

That does not even rank as high as a needle in a haystack.
 
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