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bison

Large moon may not be necessary

44 posts in this topic

Was it Melancholia that made the earth Spin around?

On a real note Go see this movie even If its a bit off topic, Its a Great Dark look at the art film world. ,Kirsten Dunst is great in this flick ! :tu:

Congratulations on your 10,000th post.

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No, they're not the same. People mistakenly presume that environments never change but we know that Earth's environment has gone through dramatic changes since life began here.

At some point the creation of new life on Earth stopped. All life today (except for parasitic viruses) can be traced to a single early life form. There is no evidence that since that life was created billions of years ago that additional life forms were created even though Earth has continued to have what we think are "ideal" conditions for the creation of life. That suggests that changes in Earth's environment have stopped the creation of new life even though the environment has been excellent at sustaining existing life and promoting its evolution. If the environment of today's Earth is so ideal for the creation of life then why hasn't it happened repeatedly?

Conversely it's possible for life to be created in ideal conditions that later become toxic and exterminate that life. We don't know the likelihood of that but we do know it happens.

If simple life evolved in the protoplanetary disk and simply rained down on Earth with the water that formed the Oceans then your assumptions are not valid.

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If simple life evolved in the protoplanetary disk and simply rained down on Earth with the water that formed the Oceans then your assumptions are not valid.

I don't see how your speculation addresses any of my points.

Has Earth's environment changed? Of course it has.

Has the creation of life on Earth stopped? With the exception of viruses, we have no evidence of any life that was created separately or independently from all life on Earth today. It can all be traced to the same early life forms.

Have the present conditions on Earth not been ideal for the creation of new life forms? Well, it hasn't happened again so something must be preventing it from happening again on Earth.

Have the conditions on Earth been good for sustaining life and promoting evolution? Look out your window.

Can the conditions on Earth change and exterminate life? Yes, the dinosaurs really died out along with millions of other species. Fortunately that tremendous change happened after a wide range of life had covered the planet. If a similar change had happened when life had just been established it very well could have been the end of all life on Earth.

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I don't see how your speculation addresses any of my points.

Has Earth's environment changed? Of course it has.

Has the creation of life on Earth stopped? With the exception of viruses, we have no evidence of any life that was created separately or independently from all life on Earth today. It can all be traced to the same early life forms.

Right, so if that early life formed in the protoplanetary disk as opposed to Earth's oceans then your argument fails.

Have the present conditions on Earth not been ideal for the creation of new life forms? Well, it hasn't happened again so something must be preventing it from happening again on Earth.

We don't know this happened on Earth, that's my point.

Have the conditions on Earth been good for sustaining life and promoting evolution? Look out your window.

Can the conditions on Earth change and exterminate life? Yes, the dinosaurs really died out along with millions of other species. Fortunately that tremendous change happened after a wide range of life had covered the planet. If a similar change had happened when life had just been established it very well could have been the end of all life on Earth.

Early life seems to have survived the late heavy bombardment and every catastrophe since. :yes:

Edited by lost_shaman

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Right, so if that early life formed in the protoplanetary disk as opposed to Earth's oceans then your argument fails.

No, it's 100% supported. Early life formed in conditions that are considered inhabitable to us, therefore the pleasant conditions we enjoy on Earth today are not the conditions that form life.

We don't know this happened on Earth, that's my point.

Yes, we don't know a lot of things but we do know every point that I made. We know that the conditions on Earth have changed dramatically in the three billion years since life was created on it and no other forms of life have been created and survived (except parasitic viruses). The formation of life seems to have happened very quickly under extremely fortunate conditions that only existed briefly. That was followed by even more extremely fortunate conditions that didn't destroy that life and allowed it to evolve to survive further climatic changes.

Early life seems to have survived the late heavy bombardment and every catastrophe since. :yes:

Yes, on Earth. We really don't know what early life was and we don't know how close it was to being destroyed. It's possible that most life in the universe never advances beyond primitive stages before it's wiped out forever. We know that Earth was an extremely lucky set of unlikely circumstances.

For some reason many people think that every planet that might have something close to Earth conditions has just gotta have life on it because it would be like so cool! When you look at the history of the Earth, you really appreciate how improbable life is.

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I see, but since it has a gravitational pull on everything then wouldn't what I said be true? (yea thanks for pointing out my mistake in system)

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We don't know that life came into being only once on this planet, or that it could only do so during a short window of opportunity. It is considered entirely possible that life existed as long ago as 4.5 billion years, was totally destroyed in the Late Heavy Bombardment at 3.9 billion years ago, and began again from scratch, perhaps as late as 3.5 billion years ago. This raises the possibility of a rather broad 'window' of up to a billion years, during which life conceivably formed, and very possibly did so repeatedly, and under a variety of conditions. Of course these are possibilities, not certainties, which is all that can be reliably said about such remote times.

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We don't know that life came into being only once on this planet, or that it could only do so during a short window of opportunity. It is considered entirely possible that life existed as long ago as 4.5 billion years, was totally destroyed in the Late Heavy Bombardment at 3.9 billion years ago, and began again from scratch, perhaps as late as 3.5 billion years ago. This raises the possibility of a rather broad 'window' of up to a billion years, during which life conceivably formed, and very possibly did so repeatedly, and under a variety of conditions. Of course these are possibilities, not certainties, which is all that can be reliably said about such remote times.

The fossil record does not agree, it shows life as just beginning 3.5 to 4 billion years ago. The only forms of life that date back 4 billion years are procaryotic cells.

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No, it's 100% supported. Early life formed in conditions that are considered inhabitable to us, therefore the pleasant conditions we enjoy on Earth today are not the conditions that form life.

I know I've said that same thing.

Yes, we don't know a lot of things but we do know every point that I made. We know that the conditions on Earth have changed dramatically in the three billion years since life was created on it and no other forms of life have been created and survived (except parasitic viruses). The formation of life seems to have happened very quickly under extremely fortunate conditions that only existed briefly. That was followed by even more extremely fortunate conditions that didn't destroy that life and allowed it to evolve to survive further climatic changes.

Look, I think you are making some strange statements. We know life evolved after it formed. What is your point? 30,000 years ago Homo Erectus, Neanderthals, and Homo Sapiens all three inhabited the Earth. Note this is about 40,000 years after Toba which is considered the major stressor of Homo Sapiens.

Yes, on Earth. We really don't know what early life was and we don't know how close it was to being destroyed. It's possible that most life in the universe never advances beyond primitive stages before it's wiped out forever. We know that Earth was an extremely lucky set of unlikely circumstances.

For some reason many people think that every planet that might have something close to Earth conditions has just gotta have life on it because it would be like so cool! When you look at the history of the Earth, you really appreciate how improbable life is.

I disagree with you. Life formed early and Thrived not simply survived. It transformed the planet into what we know today. i.e. a comfortable planet.

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The fossil record does not agree, it shows life as just beginning 3.5 to 4 billion years ago. The only forms of life that date back 4 billion years are procaryotic cells.

The known fossil record is scarcely the last word here. Is it probable that we have just happened to find the remains of the very oldest life on Earth? Can we even be certain that the earliest life left fossils that still exist today? Even if the date is 4 billion years, this is early enough to have been completely destroyed in the Late Heavy Bombardment, ~ 100 million years later. If so, life would have had to start again, under different conditions than before, and probably several hundred million years after its original inception. Edited by bison

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Look, I think you are making some strange statements. We know life evolved after it formed. What is your point?

At some point life was able to not just expand but evolve. Evolution and diversity are two requirements for the long-term survival of life. Strange statement? Maybe if you haven't heard it before.

I disagree with you. Life formed early and Thrived not simply survived. It transformed the planet into what we know today. i.e. a comfortable planet.

I can't find any evidence that it thrived (why did you capitalize that?). We don't know how long it took before it covered the planet or when it started to evolve. The evolution is what prevented it from being destroyed the planet started to change. It's possible that life on other planets was no so lucky and altered conditions to where it killed itself.

The point is that there are a lot of variables that worked out for life on Earth. Any one of those could have prevented it or wiped it out before high forms could evolve.

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The known fossil record is scarcely the last word here.

I disagree. It shows us the development of life, as well as the progression life took.

Is it probable that we have just happened to find the remains of the very oldest life on Earth?

Well, yes, we have seen the remains of the oldest life on earth, and it is microbial. And with the model of life that we have today, that progression makes perfect sense.

Can we even be certain that the earliest life left fossils that still exist today?

Yes, we have a record of them, and the transitions made to the many complex forms we see today.

Even if the date is 4 billion years, this is early enough to have been completely destroyed in the Late Heavy Bombardment, ~ 100 million years later. If so, life would have had to start again, under different conditions than before, and probably several hundred million years after its original inception.

Very different conditions, earth had no atmosphere. It has been replaced three times. The first atmosphere was primarily H & He, which was blasted away before the planet established magnetic fields. Once they were established, the atmosphere filled with sulfurous, nitrogenous and carbon compounds. This is when life began to take hold, and anaerobic organisms stared to produce oxygen, which was the catalyst for life, even though it was a poisonous byproduct to any life at the time. Are you taking into account coalescence, the formation of the moon, the formation of the atmosphere, and the cool down period after that? How much time does that leave you to sterilize earth, and then start all over again, without a trace of previous forms after all that has taken place?

This is what the world is proposed to have looked like during heavy bombardment

Lunar_cataclysm.jpg

Do you have any reason to believe life sprung forth during this turbulent period?

Edited by psyche101

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We don't know that life came into being only once on this planet, or that it could only do so during a short window of opportunity.

That's true. We only know that we haven't found any traces of this other life but the odds of that are extremely small in any case.

It is considered entirely possible that life existed as long ago as 4.5 billion years, was totally destroyed in the Late Heavy Bombardment at 3.9 billion years ago, and began again from scratch, perhaps as late as 3.5 billion years ago. This raises the possibility of a rather broad 'window' of up to a billion years, during which life conceivably formed, and very possibly did so repeatedly, and under a variety of conditions.

That is certainly possible, but then you have to ask, "Why were these ancient conditions prime for the repeated formation of life but the four billion years after it were not?" I think that holds the key to the formation of life (on any planet) but we don't know what it is.

Of course these are possibilities, not certainties, which is all that can be reliably said about such remote times.

Yes, they're not even probabilities. We know so very little about the formation of life on Earth that it's hard to speculate how it would happen on other planets.

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I disagree with you. Life formed early and Thrived not simply survived. It transformed the planet into what we know today. i.e. a comfortable planet.

I suspect in these early years there was still quite some bombardment, it strikes me that once life took hold, it would be hard to end life as billions and billions of tiny organisms. We know all water bodies on early earth were loaded with Coacervates, so you would have to near destroy the planet, or at least everything on it to wipe life out once it takes hold. It would be easy to destroy one big thing, but much harder to destroy billions of tiny things.

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The known fossil record is scarcely the last word here. Is it probable that we have just happened to find the remains of the very oldest life on Earth? Can we even be certain that the earliest life left fossils that still exist today? Even if the date is 4 billion years, this is early enough to have been completely destroyed in the Late Heavy Bombardment, ~ 100 million years later. If so, life would have had to start again, under different conditions than before, and probably several hundred million years after its original inception.

Genetic evidence suggests life was present by 4.29 Ga, therefore life on Earth survived the Late Heavy Bombardment.

http://www.evolbiol.ru/large_files/sheridan.pdf

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Genetic evidence suggests life was present by 4.29 Ga, therefore life on Earth survived the Late Heavy Bombardment.

http://www.evolbiol.ru/large_files/sheridan.pdf

Top link mate

We propose a date of 4.29 Ga for the Last Common Ancestor of the Bacterial and Archaeal Domains and a date of 3.46 Ga for the Bacterial and Archaeal Domain individual radiations. These divergence times do not conflict with geological evidence but call into question the interpretation of early Archean (»3.5 Ga) microfossils as evidence of cyanobacterial lineages

Dated 2003! I Must keep up, I had only heard about the 4 billion threshold about 6 months ago :blush: I was still looking for a link. Thanks for that :tu:

Edited by psyche101

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Interesting article. It suggests the possibility that forms of life arose completely independently of ours, and persist to this day. Since most organisms remain genetically uncharacterized, we can scarcely rule this out. We wouldn't know if, or when they began. http://www.guardian.co.uk/science/2009/feb/15/microbes-earth-tree-of-life

Edited by bison

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Interesting article. It suggests the possibility that forms of life arose completely independently of ours, and persist to this day. Since most organisms remain genetically uncharacterized, we can scarcely rule this out. We wouldn't know if, or when they began. http://www.guardian.co.uk/science/2009/feb/15/microbes-earth-tree-of-life

Is there any traces of anything that give rise to such reasoning? Or is it pie in the sky stuff?

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Interesting article. It suggests the possibility that forms of life arose completely independently of ours, and persist to this day. Since most organisms remain genetically uncharacterized, we can scarcely rule this out. We wouldn't know if, or when they began. http://www.guardian.co.uk/science/2009/feb/15/microbes-earth-tree-of-life

It sort of reminds me of the ideal of life on Europa. Even if we find life there, is it Alien? Not really if it carries the same signatures that life on earth does. We might have seeded life through panspermia. Even should we find life on another planet, there are still real hurdles to overcome before it can be considered as truly Alien.

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