An astronomer calculated that Earth's intelligent life is probably 'rare.' Here's what that means.

May 30, 2020
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Given the median age of the Earth's crust is roughly 2bn yes, with very small pockets of older rock.

It's also possible that the fossil record prior to this point is mostly missing.

We could be a later iteration of complex life on Earth.

The fossil record is also dependent on the chemistry of the life that exists at that time.

Such as it is plausible that jellyfish are much older than the Cambrian explosion, as they rarely fossilise and appear as the complex creatures very early.

Intelligent life may have risen on Earth many times with the evidence of that life destroyed due to the evolution of the Earth itself.

Now no one has any evidence of this, it is pure speculation.

But this analysis is based on assumptions, which may or may not be true.
 
Apr 9, 2020
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Concur about the possibility of intelligent life having risen multiple times on Earth without our knowledge of it. Why not a race more intelligent than us who existed shortly before one of Earth's mass extinction events, saw it coming, so packed up and left Earth, intentionally destroying evidence of its existence so as not to influence future (intelligent) species? That's what we would do, if we were capable (and not so vain as to insist on leaving our garbage behind).

On the other hand, that civilization might just have been visiting Earth for millions of years (for the weather/beaches or for dinosaur hunting) and then left town in a hurry.
 
Jun 8, 2020
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The article stated "Once atmospheric CO2 drops below 10 parts per million, plants will die off ...." I believe this statement is in error by an order of magnitude. Green (photosynthetic) plant life on this planet dies off when atmospheric CO2 falls below 150 ppm... a much higher concentration than the claimed 10 ppm.
 
Jun 8, 2020
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One critical factor that wasn't mentioned in the article is life form morphology and environment. There is substantial evidence that dolphins may have mental capabilities similar to humans, but they obviously lack functional abilities similar to humans. And it's functional abilities that allow for a species to develop the technologies required for interstellar communication and travel, what we would typically think of an ETI being capable of, provided it's at or a little above our technological level. My point is, the fact that all SETI efforts so far have been unsuccessful does not necessarily indicate that there is a rarity of intelligence elsewhere (of course there's also debate on just how extensive a search must be to find ETI, but that's another matter), because "intelligence" does not necessarily mean "enabling technology" insofar as having at least one successful SETI.
One other issue that's been commented on, I've come across discussions before regarding the possibility that there may have been intelligent species in Earth's distant past but they either went extinct or "left" so long ago there wouldn't be any traces remaining of their existence. That's certainly possible, but IMHO very unlikely, the main reason being that the fossil record since the Cambrian is fairly complete, although there are still discoveries being made. Any intelligent species would have to possess a brain (relative to body size) much larger than any found in the fossil record, with their genetic cousins similarly equipped (just as present day primates are similar to humans), and nothing even close has ever been retrieved. The paleontological record seems to be quite clear in this respect, with life form complexity roughly proportional to geologic time, the earliest being the simplest, and brains increase in size to accommodate the increasing complexity of the nervous system.
 
Jun 8, 2020
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The article stated "Once atmospheric CO2 drops below 10 parts per million, plants will die off ...." I believe this statement is in error by an order of magnitude. Green (photosynthetic) plant life on this planet dies off when atmospheric CO2 falls below 150 ppm... a much higher concentration than the claimed 10 ppm.
John, I found a source to back you up...

"The amount of CO2 in the atmosphere was reduced by about 90% during the last 150 million years. If this trend continues CO2 will inevitably fall to levels that threaten the survival of plants, which require a minimum of 150 ppm to survive"

- http://sepwww.stanford.edu/sep/jon/climate.html
- 9th paragraph, about midpoint
 
Dec 11, 2019
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John, I found a source to back you up...

"The amount of CO2 in the atmosphere was reduced by about 90% during the last 150 million years. If this trend continues CO2 will inevitably fall to levels that threaten the survival of plants, which require a minimum of 150 ppm to survive"

- http://sepwww.stanford.edu/sep/jon/climate.html
- 9th paragraph, about midpoint
Pardon me if I am wrong but don't Greta and the "Climate Change" "gurus" want to drop CO2 to NET ZERO?
 
Dec 11, 2019
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No, they want to drop the RATE OF INCREASE to zero, or even a little negative until we get back down to ~300-350ppm.
Thanks for your interpretation. On paper that seems like a good thing. The only problem is getting the whole world to change from the globalist systems and giant polluting corporations. I also don't see politicians. ceo's and celebrities stopping living in their big mansions and flying their private jets. They only want the serfs and peasants to change their lives while they live like kings and queens. That is the problem.
 
Mar 19, 2020
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Based on the on-going mass extinction caused by human activities, which will ultimately result in our demise, who says that intelligent life exists on this planet, much less somewhere else?!

A species that blithely goes about its polluting, over-populating ways, knowing full well that this will eventually extinguish itself, should fall under the category of "knows enough to be dangerous". A few rungs below an "intelligent" rating, one should think.

Some might suggest that intelligence is a higher level of thought processes than humans do not currently possess. Greed and indifference seems to be our biggest mental defects preventing us from reaching that designation.

Beam me up, Scotty - no intelligent life here!
 
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Dec 8, 2019
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It seems that the article misses one important point regarding intelligent life developing and that is oxygen. If Earth's life developed quickly as is suggested, that life would rely on CO2, where the oxygen would be released and the carbon retained. Life would be anaerobic. This form of life as shown does not develop into more complex lifeforms. But it does something valuable for more complex life. It releases oxygen.

Now over billions of years pure oxygen has been released by these life forms, but it tended to combine with other elements, as oxygen does. Iron is a perfect example. Also CO2 continued to be created, but it continued to feed these lifeforms. Eventually oxygen began to run out of elements it could combine with easily and started to accumulate in our atmosphere. It took billions of years to occur and when it reached a level approaching what we have today, anaerobic life started to die off.

Somewhere along the journey mutations occurred that developed oxygen feeding life.. And oxygen being a far more volatile element than the CO2 molecule, seems to have led to increasingly rapid evolution. Still took another billion years or more but finally the increasingly complex lifeforms developed. Sex was the next major stepping stone and by 550 million years ago, the complex lifeforms started to blossom, leading to increasing complexity and intelligence.

Our complex life and eventually intelligence, needed atmospheric oxygen and that took billions of years to be formed out of earlier life forms that released it as a poison. If life tends to follow this path and the planet is revolving around a stable K or G star, it would appear that complex life would be an eventual outcome.
 
Apr 18, 2020
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It seems that the article misses one important point regarding intelligent life developing and that is oxygen. If Earth's life developed quickly as is suggested, that life would rely on CO2, where the oxygen would be released and the carbon retained. Life would be anaerobic. This form of life as shown does not develop into more complex lifeforms. But it does something valuable for more complex life. It releases oxygen.

Now over billions of years pure oxygen has been released by these life forms, but it tended to combine with other elements, as oxygen does. Iron is a perfect example. Also CO2 continued to be created, but it continued to feed these lifeforms. Eventually oxygen began to run out of elements it could combine with easily and started to accumulate in our atmosphere. It took billions of years to occur and when it reached a level approaching what we have today, anaerobic life started to die off.

Somewhere along the journey mutations occurred that developed oxygen feeding life.. And oxygen being a far more volatile element than the CO2 molecule, seems to have led to increasingly rapid evolution. Still took another billion years or more but finally the increasingly complex lifeforms developed. Sex was the next major stepping stone and by 550 million years ago, the complex lifeforms started to blossom, leading to increasing complexity and intelligence.

Our complex life and eventually intelligence, needed atmospheric oxygen and that took billions of years to be formed out of earlier life forms that released it as a poison. If life tends to follow this path and the planet is revolving around a stable K or G star, it would appear that complex life would be an eventual outcome.
You might want to tighten up a little on those "billions of years." You've only got about 4.5 billion years to work with.
 
Apr 18, 2020
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Thanks for your interpretation. On paper that seems like a good thing. The only problem is getting the whole world to change from the globalist systems and giant polluting corporations. I also don't see politicians. ceo's and celebrities stopping living in their big mansions and flying their private jets. They only want the serfs and peasants to change their lives while they live like kings and queens. That is the problem.
Aside from ascribing motives to people you don't know, all the "politicians. ceo's and celebrities" in the world don't make a measurable difference. There's not enough of them. And even if your claim were true, why is that "the problem"? If we have millions of people thinking "I won't do it, because Al Gore doesn't do it," that would seem to be a bigger problem. Pointing fingers doesn't absolve the rest of us.
 
Dec 8, 2019
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You might want to tighten up a little on those "billions of years." You've only got about 4.5 billion years to work with.

According to scientific studies it took at least 2 billion years for the Earth to gain a sufficiently oxygenated atmosphere comparable to what we now have, as a result of the input of anaerobic life forms. Then because of the reduction of CO2, the Earth's atmosphere cooled a little over 2-2.5 billion years ago, coinciding when oxygen became a principle gas in the atmosphere and multicellular organisms first appeared.

Probably volcanic activity which increased CO2, brought the Earth back into a warm period but again the Earth's atmosphere cooled dramatically about 750 million years ago, bringing about what was theorised as the Snowball Earth where glaciers were believed to have almost reached the tropics. It seems volcanic activity again warmed the Earth by increasing CO2 levels and since then there has been more or less a balance between O2 and CO2 levels that has maintained a warm period during which complex lifeforms developed significantly.

We are now in a cooling period (interfered with by human activity) brought about mainly by the movement of the continents restricting water movement.

So 4.5 billion years back the Earth formed. Probably life began around 3.5 to 4 billion years ago. Oxygen became a dominant gas in the atmosphere around 2-2.5 billion years ago coinciding with the first appearance of multicellular organisms during a cooling period. Then 750 million years back, reduced CO2 led to Snowball Earth. 550 million years ago the atmosphere warmed again, followed by the blooming of more complex multi cellular creatures.

It is surely no coincidence that multi-cellular life forms started to appear and then thrived at the time when oxygen became one of the primary components of the atmosphere, and that process eventually led to us.
 
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Dec 11, 2019
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Based on the on-going mass extinction caused by human activities, which will ultimately result in our demise, who says that intelligent life exists on this planet, much less somewhere else?!

A species that blithely goes about its polluting, over-populating ways, knowing full well that this will eventually extinguish itself, should fall under the category of "knows enough to be dangerous". A few rungs below an "intelligent" rating, one should think.

Some might suggest that intelligence is a higher level of thought processes than humans do not currently possess. Greed and indifference seems to be our biggest mental defects preventing us from reaching that designation.

Beam me up, Scotty - no intelligent life here!
I agree and the human race here is very easily manipulated and controlled. Just look at the last 6 months and you can see how easily the MSM controls the world with it's narratives.
 
Dec 11, 2019
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Aside from ascribing motives to people you don't know, all the "politicians. ceo's and celebrities" in the world don't make a measurable difference. There's not enough of them. And even if your claim were true, why is that "the problem"? If we have millions of people thinking "I won't do it, because Al Gore doesn't do it," that would seem to be a bigger problem. Pointing fingers doesn't absolve the rest of us.
Well to agree with you the 99 percent are the ones that keep the 1 percent in power. So yes it is all of our faults for letting them control us for far to long.
 

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