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How many earths in our galaxy .....

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#1 Ian Robinson

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Posted 20 February 2015 - 03:26 AM

http://exoplanets.ne...entistapps.com/

 

Kepler's haul = 3588 in sampled region of space

In Goldielocks zones = 1966

of these 51 are earthlike (mass) and extrapolating for undetectable (by telescope) 22500 earths in that region  of space

==> galaxy wide 15-20 billion earths.

 

Of cause we now know that large moons orbiting large gas giants can also be likely homes for life even if they are well outside the Goldielocks zone of the parent star.

 

 

Anyone's guess how many have evolved life and likely not many will have "smart" inhabitants , even fewer will have inhabitants at least as well developed technologically as us or have been colonised by nonindigenous spacefaring beings .


Edited by Ian Robinson, 20 February 2015 - 03:31 AM.


#2 MikeBOKC

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Posted 20 February 2015 - 08:11 AM

Well Kepler has filled in one of the key parts of the Drake equation in ways that sure point to a final solution that is greater than many would have projected. It's pretty clear that planets are common and almost requisite for most stars. It does not take a giant leap of logic to suggest that the evolution of life is also very probably common too.


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#3 astroMakemake42

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Posted 20 February 2015 - 08:17 AM

A possibility to consider is that it is possible some planets of a star system may have the right alignment relative to their host star  to be detected by Kepler others may not, raising the possible number of other Earths a little bit.  


Edited by astroMakemake42, 20 February 2015 - 08:18 AM.


#4 astroneil

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Posted 20 February 2015 - 08:42 AM

 It does not take a giant leap of logic to suggest that the evolution of life is also very probably common too.

 

I disagree. I don't think it's scientific to think this way.

 

Best,

 

Neil. ;)


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#5 llanitedave

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Posted 20 February 2015 - 10:56 AM

But it's logical. The "principal of mediocrity" would suggest that there is nothing extraordinary about the Sun, the solar system in general, or the Earth. The Earth's formation and early history, as far as is known so far, didn't involve any events or circumstances that would not plausibly occur on a large number of other planets in formation. Therefore, the chemistry that led to the origin of life on Earth would not be likely to be extraordinarily unusual.

The alternative, to think of life as "a miracle", is what is unscientific. That said, I'm inclined to think there there are a lot more ways to NOT develop life than there are to do it successfully, so the living planets are most likely a small minority. I don't think it's implausible to suggest that some of Earth's early conditions may have been somewhat unusual.


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#6 astroneil

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Posted 20 February 2015 - 11:03 AM

But it's logical.

It's not logical, merely wishful thinking.

 

But we need to be careful what we wish for.

 

Best,

 

Neil. ;)


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#7 GJJim

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Posted 20 February 2015 - 11:34 AM

But it's logical. The "principal of mediocrity" would suggest that there is nothing extraordinary about the Sun, the solar system in general, or the Earth. The Earth's formation and early history, as far as is known so far, didn't involve any events or circumstances that would not plausibly occur on a large number of other planets in formation. Therefore, the chemistry that led to the origin of life on Earth would not be likely to be extraordinarily unusual.

Exactly what is the "the chemistry that led to the origin of life on Earth"? There is no coherent scientific rationale for abiogenesis. Many theories yes, no experimental evidence to support a claim that life is inevitable and ubiquitous.


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#8 MikeBOKC

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Posted 20 February 2015 - 01:27 PM

Well common wisdom in astronomy and cosmology is that the laws of physics are the same everywhere in the known universe, Light speed is light speed, gravity is gravity. It is also clear that the chemical elements known here are also found there, wherever there is, in comparable ratios. I don't think it's an unjustified extrapolation to suggest that that biological processes, including the origin of life and natural selection, are very likely universally possible as well.


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#9 llanitedave

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Posted 20 February 2015 - 01:34 PM

 

But it's logical. The "principal of mediocrity" would suggest that there is nothing extraordinary about the Sun, the solar system in general, or the Earth. The Earth's formation and early history, as far as is known so far, didn't involve any events or circumstances that would not plausibly occur on a large number of other planets in formation. Therefore, the chemistry that led to the origin of life on Earth would not be likely to be extraordinarily unusual.

Exactly what is the "the chemistry that led to the origin of life on Earth"? There is no coherent scientific rationale for abiogenesis. Many theories yes, no experimental evidence to support a claim that life is inevitable and ubiquitous.

 

It's a devilishly difficult problem, but it's far from one that calls for a miracle.  I don't think I claimed that life is "inevitable and ubiquitous", in fact my post indicated just the opposite.  It doesn't have to be inevitable and ubiquitous to be occasional and rare, while falling short of miraculous or an act of divine intervention.

The proto-chemistry of life IS inevitable and ubiquitous.  Experimental evidence shows that sugars, amino acids, and lipids are ubiquitous in environments similar to those of Early earth.  Simple nucleotides can also be found.

There are obstacles, but none of them seem insurmountable.  Chirality is one, but there are several processes that can enrich molecules of one orientation over those of another.  Mineral substrates seem to be necessary for RNA and some of the other structural peptides, but different substrates have different properties, and promote different types of combinations.  There is an issue over having the products of one substrate be in contact with those of another, whether the substrates are ice, carbonates, clays, or rocks such as basalt.

There are a huge variety of sub-environments that need to be investigated -- the problem is not that any particular chemical precursor is difficult, but that there are so many of them.  They will interact in tremendously complex ways.

I don't think it's unreasonable at all to suppose that on a huge number of newborn planets the right combinations of circumstances and events simply didn't happen, due to one minor detail or another.  But the fact remains that it DID happen on at least one planet, and that planet does not appear to be in any way extraordinary in its physical and chemical history.  It doesn't have to have happened everywhere in order to have happened more than once, and there are a lot of other "natural experiments" that we're now learning about that will in principle allow us to discover what conditions work, and what conditions don't.


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#10 dyslexic nam

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Posted 20 February 2015 - 01:40 PM

The fact that we haven't explained abiogenesis does not negate the fact that it occured.  At some point in earth's history, earth's "stuff" changed from disorganized non-living material to organized living material.  Setting aside a few theories that are completely outside the realms of science, it is reasonable to conclude that there is some scientifically explainable way this occured.   And unless we find evidence that there was something extremely rare and exceptional about early earth, then it makes sense to expect the same result when the experiment is repeated over trillions of planets in the universe.

 

That IS logical.  


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#11 jrbarnett

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Posted 20 February 2015 - 01:48 PM

http://exoplanets.ne...entistapps.com/

 

Kepler's haul = 3588 in sampled region of space

In Goldielocks zones = 1966

of these 51 are earthlike (mass) and extrapolating for undetectable (by telescope) 22500 earths in that region  of space

==> galaxy wide 15-20 billion earths.

 

Of cause we now know that large moons orbiting large gas giants can also be likely homes for life even if they are well outside the Goldielocks zone of the parent star.

 

 

Anyone's guess how many have evolved life and likely not many will have "smart" inhabitants , even fewer will have inhabitants at least as well developed technologically as us or have been colonised by nonindigenous spacefaring beings .

And the Goldilocks Zone is such only if you assume carbon based life forms somewhat like us and our close (biochemistry) cousins, the amoeba and the yucca plant.  Non-carbon-based life is not just possible, but probable.  Most of these theories and models fail to account for that when projecting the probability of life elsewhere in the Universe.

 

But our current understanding of physics helps explain why it is, in a Universe that is suspected to be teaming with planets suitable for carbon based life, we aren't pen pals with any of our suspected neighbors.  The fastest mode of communication we have at our disposal is light, which tops out at the speed of light.  The fastest mode of physical transport, with or without a human aboard, tops out at about 38,000 mph (current velocity of the Voyager probes).  

 

Even if we could project a coherent light beam capable of being targeted on the nearest non-Goldilocks exoplanet orbiting Alpha Centauri (dubbed Alpha Centauri Bb), it would take the beam 4.23 years from emission to arrive at the target.  Traveling to Alpha Centauri (robotically or otherwise) at 38,000mph would take approximately 78 thousand years, for reference.  What intelligent technological life was on Earth 78 thousand years ago?  Over the next 78 thousand year span, what is the likelihood of mass extinction events eliminating most life forms on Earth?  The nearest Goldilocks planet orbits Tau Certi which is more than 11 light years away.  You do the math.

 

The distances involved are so vast, that without some form of FTL travel and/or communication, the chances of one intelligent, technologically capable civilization coexisting simultaneously with us and being in close enough proximity to us to be able to technologically communicate with us, are exceedingly remote.  Your odds of being struck dead my a meteor whilst being attacked by a Great White shark on the very day you won a half billion Dollar jackpot in the Powerball Lottery are hundreds of millions of times better.  

 

Evolution is slow.  How long did it take for Homo Habilis to evolve into new species leading to Homo Sapiens?  For Homo Sapiens, how long has it taken us to evolve from early examples of the species to current stature (greater average height, weight, physical and intellectual capabilities, etc.)?  What are the odds of any two proximate (in a galactic location sense) intelligent technological civilizations each achieving a level of evolution and technology allowing mutual communication over these vast distances at the same point in time?  Astronomical.  But eventually evolution will give us the cranial capacity necessary for our entire species to abandon ignorance and primitive superstitions.  As a species we've already made great strides along this path, but the path is long and we have many miles to go before we rest.  

 

Pending credible technological advancements or physics discoveries for overcoming the great governor, the speed of light, I will acknowledge that while it is almost 100% certain that other intelligent technological life exists in the Universe right now, it is also almost 100% certain that no person living today will ever know it.  We are, for all practical inter-planetary civilization communication, combat or commerce intents and purposes, currently alone.

 

Given such, let's not **** up the Big Blue Marble too badly, eh?

 

:grin:

 

- Jim 


Edited by jrbarnett, 20 February 2015 - 03:29 PM.

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#12 Rick Woods

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Posted 20 February 2015 - 02:02 PM

Trick question!

Real answer: One.


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#13 jrbarnett

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Posted 20 February 2015 - 02:56 PM

Trick question!

Real answer: One.

The probability of that being the real answer is equal to the probability of being struck dead by a meteor whilst being attacked by a Great White shark and simultaenously flipping a quarter landing seventeen consecutive "edge" flips (i.e., neither heads nor tails) on the very day you also won a half billion Dollar jackpot in the Powerball Lottery.

 

But your answer reminds me that I have a business proposition for you.  I have some ocean frontage to sell you in Flagstaff for a very good price.  Interested?

 

:grin:

 

- Jim


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#14 astroneil

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Posted 20 February 2015 - 03:14 PM

The fact that we haven't explained abiogenesis does not negate the fact that it occured. 

Abiogeneis is impossible. You would need far more time than the age of the cosmos and far more matter than is contained in the cosmos to get anything viable. Most folk don't understand that.

 

We are here for a reason.

 

There is no need to debate it either; all one need do is sit back and watch as new discoveries come to the fore.

 

We need to get used to being alone.

 

Best,

 

Neil. ;)


Edited by astroneil, 20 February 2015 - 03:22 PM.

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#15 jrbarnett

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Posted 20 February 2015 - 03:30 PM

The fact that we haven't explained abiogenesis does not negate the fact that it occured.  At some point in earth's history, earth's "stuff" changed from disorganized non-living material to organized living material.  Setting aside a few theories that are completely outside the realms of science, it is reasonable to conclude that there is some scientifically explainable way this occured.   And unless we find evidence that there was something extremely rare and exceptional about early earth, then it makes sense to expect the same result when the experiment is repeated over trillions of planets in the universe.

 

That IS logical.  

Yes, but logic and superstition make strange bedfellows.

 

:thinking:

 

- Jim


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#16 ColoHank

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Posted 20 February 2015 - 03:58 PM

 

The fact that we haven't explained abiogenesis does not negate the fact that it occured. 

Abiogeneis is impossible. You would need far more time than the age of the cosmos and far more matter than is contained in the cosmos to get anything viable. Most folk don't understand that.

 

We are here for a reason.

 

There is no need to debate it either; all one need do is sit back and watch as new discoveries come to the fore.

 

We need to get used to being alone.

 

Best,

 

Neil. ;)

 

OK, let's suppose that the emergence of life on Earth isn't due to abiogenesis, but rather is the product of some divine hand.  Is there any reason that the same thing couldn't have happened in a multitude of places?  I mean, if there's an omnipotent presence out there creating vast, uncountable numbers of different kinds of worlds, some of which no doubt closely resemble our own, then why would such a power be content to populate only one of them with living things?  What could possibly constrain or prevent it from doing otherwise?

 

I think the needle swings toward a rich abundance of life throughout the immensity of the universe, regardless of its origin.  Why not?  Life is certainly diverse and broadly distributed here on Earth, from one environmental extreme to the other.  Whether or not we might recognize an alien life-form, whether or not it might be intelligent and capable of communicating or traveling over interstellar distance, and whether or not it might exist in our spatial or temporal frames of reference are different matters to consider.


Edited by ColoHank, 20 February 2015 - 04:02 PM.

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#17 llanitedave

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Posted 20 February 2015 - 04:03 PM

The fact that we haven't explained abiogenesis does not negate the fact that it occured.

Abiogeneis is impossible. You would need far more time than the age of the cosmos and far more matter than is contained in the cosmos to get anything viable. Most folk don't understand that.


Most scientists who are actually working on the problem understand quite well that statements like the above are false.
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#18 astroneil

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Posted 20 February 2015 - 04:09 PM

There is a recent book I can recommend to help those interested in grappling with this old chestnut;

 

Origins of Life; Biblical and Creation Models Face Off by Hugh Ross and Fazale Rana. They are Christians with backgrounds in astrophysics and biochemistry, respectively.

 

http://www.amazon.co...howViewpoints=1

 

Please don't be offended by their faith (as opposed to 'superstition'); but the arguments they use deserve to be heard by as many people as possible.

 

I direct you to the reviews of this book. That should get you started.

 

Hope this helps,

 

Neil. ;)


Edited by astroneil, 20 February 2015 - 04:11 PM.

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#19 Crow Haven

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Posted 20 February 2015 - 04:16 PM

I get stuck on getting something from nothing... How can there be nothing?

I like to think there's life on other planets, but I don't know.
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#20 jrbarnett

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Posted 20 February 2015 - 04:18 PM

 

 

The fact that we haven't explained abiogenesis does not negate the fact that it occured. 

Abiogeneis is impossible. You would need far more time than the age of the cosmos and far more matter than is contained in the cosmos to get anything viable. Most folk don't understand that.

 

We are here for a reason.

 

There is no need to debate it either; all one need do is sit back and watch as new discoveries come to the fore.

 

We need to get used to being alone.

 

Best,

 

Neil. ;)

 

OK, let's suppose that the emergence of life on Earth isn't due to abiogenesis, but rather is the product of some divine hand.  Is there any reason that the same thing couldn't have happened in a multitude of places?  I mean, if there's an omnipotent presence out there creating vast, uncountable numbers of different kinds of worlds, some of which no doubt closely resemble our own, then why would such a power be content to populate only one of them with living things?  What could possibly constrain or prevent it from doing otherwise?

 

I think the needle swings toward a rich abundance of life throughout the immensity of the universe, regardless of its origin.  Why not?  Life is certainly diverse and broadly distributed here on Earth, from one environmental extreme to the other.  Whether or not we might recognize an alien life-form, whether or not it might be intelligent and capable of communicating or traveling over interstellar distance, and whether or not it might exist in our spatial or temporal frames of reference are different matters to consider.

 

Further, there is a rich fossil record of abundant diversity of life on Earth at different periods going back millions of years, including multitudes of both still extant as well as extinct species including hominids.  Yet no ecclesiastical writing of any faith, no matter its specific creation/creator belief, addresses the *fact* of the long history of life on Earth or the existence of multitudes of now extinct species.  The best any of them can do is truly silly theories that Earth or the Universe is only thousands of years old.  The poly-theistic Maya, for example, had an elaborate calendaring system that precisely dated events in their origin myths.

 

But you would expect an omniscient creator or creators (let's not leave the pagans out - historically they were far wiser than many monotheistic societies after all), who often communicated fantastical/mystical/miraculously-implausible things to its followers, not to leave out things about the extinct species it created previously.  Moreover, there's a damning coincidence that can't be ignored when assessing probabilities of intelligent life.  Every single cult in all of history that has ever claimed that we are alone and unique, mentions only species of flora and fauna that were in existence in the region and time period during which those cults first emerged.  That coincidence rather clinches it for the "abundant life in the universe" folks since the contrarian perspectives are revealed to be anachronistically ignorant consistent with the level of ignorance of the peoples who first practiced those belief systems.

 

The *fact* that earthly ecclesiastical authorities can be and often are factually wrong is undeniable.  Certain sects used to violently impose faith in the Earth-centric solar system on followers.  Those same sects today acknowledge that their faith was in error.  To err is human, whether with respect to solar system structure or species origins.   :thinking:

 

- Jim 


Edited by jrbarnett, 20 February 2015 - 05:14 PM.

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#21 dyslexic nam

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Posted 20 February 2015 - 04:22 PM

I won't be reading it.  Accuse me of closemindedness, I suppose, but I have thought about and debated this topic ad nauseum (courtesy of 7 years of study in philosophy - this comes up pretty often).  I will simply say that I have found no compelling reason to accept concepts and allegations that defy all observable reality and which would require an entire extra metaphysics that we have never seen a single data point of evidence to support.

 

ymmv 


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#22 jrbarnett

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Posted 20 February 2015 - 04:23 PM

I get stuck on getting something from nothing... How can there be nothing?

I like to think there's life on other planets, but I don't know.

Well fortunately that is the only "logical" position a fully evolved Homo Sapiens can take in the absence of factual data to the contrary.

 

:grin:

 

I'm in the same boat.  Looking at the facts and theories and myths and belief systems related to the issue, I am persuaded that widespread life is more probable, but unless and until we have actual examples of extra-terrestrial life, I can't claim to *know* that life abounds elsewhere.

 

I have the added burden of also believing that due to evolutionary timelines the distances involved and the limits of our technology, we are unlikely as a species to ever obtain dispositive facts either way.

 

A rapidly rising theory of cosmology now holds that there was *never* nothing; that is the universe and everything in it is infinite in a time sense.  That kind of solves the old "first mover" paradox.  You can't have something from nothing ergo someone must have created the something, that someone being the first mover.  But, um, er, well, where did the first mover come from?  :lol:  If the first mover was infinite, why couldn't the purported creation, instead, have been infinite.  Evolution in evidence; Aquinas might have pulled the wool over the eyes of the helpless and hopeless in the 13th century Dark Ages, but our bigger brains know better now.

 

- Jim


Edited by jrbarnett, 20 February 2015 - 05:06 PM.

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#23 astroneil

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Posted 20 February 2015 - 04:25 PM

 

 

 

The fact that we haven't explained abiogenesis does not negate the fact that it occured. 

Abiogeneis is impossible. You would need far more time than the age of the cosmos and far more matter than is contained in the cosmos to get anything viable. Most folk don't understand that.

 

We are here for a reason.

 

There is no need to debate it either; all one need do is sit back and watch as new discoveries come to the fore.

 

We need to get used to being alone.

 

Best,

 

Neil. ;)

 

OK, let's suppose that the emergence of life on Earth isn't due to abiogenesis, but rather is the product of some divine hand.  Is there any reason that the same thing couldn't have happened in a multitude of places?  I mean, if there's an omnipotent presence out there creating vast, uncountable numbers of different kinds of worlds, some of which no doubt closely resemble our own, then why would such a power be content to populate only one of them with living things?  What could possibly constrain or prevent it from doing otherwise?

 

I think the needle swings toward a rich abundance of life throughout the immensity of the universe, regardless of its origin.  Why not?  Life is certainly diverse and broadly distributed here on Earth, from one environmental extreme to the other.  Whether or not we might recognize an alien life-form, whether or not it might be intelligent and capable of communicating or traveling over interstellar distance, and whether or not it might exist in our spatial or temporal frames of reference are different matters to consider.

 

Further, there is a rich fossil record of abundant diversity of life on Earth at different periods going back millions of years, including multitudes of both still extant as well as extinct species including hominids.  Yet no ecclesiastical writing of any faith, no matter its specific creation/creator belief, addresses the *fact* of the long history of life on Earth or the existence of multitudes of now extinct species.  The best any of them can do is truly silly theories that Earth or the Universe is only thousands of years old.  The poly-theistic Maya, for example, had an elaborate calendaring system that precisely dated events in their origin myths.

 

But you would expect an omniscient creator or creators (let's not leave the pagans out - historically they were far wiser than many monotheistic societies after all), who often communicated fantastical/mystical/miraculously-implausible things to its followers, not to leave out things about the extinct species it created previously.  Moreover, there's a damning coincidence that can't be ignored when assessing probabilities of intelligent life.  Every single cult in all of history that has ever claimed that we are alone and unique, mentions only species of flora and fauna that were in existence in the region and time period during which those cults first emerged.  That coincidence rather clinches it for the "abundant life in the universe" folks since the contrarian perspectives are revealed to be anachronistically ignorant consistent with the level of ignorance of the peoples who first practiced those belief systems.

 

The *fact* that earthly ecclesiastical authorities can and often are factually wrong is undeniable.  Certain sects used to violently impose faith in the Earth-centric solar system on followers.  Those same sects today acknowledge that their faith was in error.  To err is human, whether with respect to solar system structure or species origins.   :thinking:

 

- Jim 

 

;)



#24 Footbag

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Posted 20 February 2015 - 04:30 PM

There is a recent book I can recommend to help those interested in grappling with this old chestnut;

 

Origins of Life; Biblical and Creation Models Face Off by Hugh Ross and Fazale Rana. They are Christians with backgrounds in astrophysics and biochemistry, respectively.

 

http://www.amazon.co...howViewpoints=1

 

Please don't be offended by their faith (as opposed to 'superstition'); but the arguments they use deserve to be heard by as many people as possible.

 

I direct you to the reviews of this book. That should get you started.

 

Hope this helps,

 

Neil. ;)

 

So...  Is it about science or creation?



#25 jayhall0315

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Posted 20 February 2015 - 04:32 PM

 

The fact that we haven't explained abiogenesis does not negate the fact that it occured. 

Abiogeneis is impossible. You would need far more time than the age of the cosmos and far more matter than is contained in the cosmos to get anything viable. Most folk don't understand that.

 

We are here for a reason.

 

There is no need to debate it either; all one need do is sit back and watch as new discoveries come to the fore.

 

We need to get used to being alone.

 

Best,

 

Neil. ;)

 

 

Neil, I respectfully disagree. For the past five semesters it has been my unhappy duty to teach undergraduate engineering majors Thermodynamics II, and we occasionally handle this problem of life and self organization of matter as a bonus problem or mini-project. I will skip the mathematical description for now and say that what distinguishes life from non-life is its self organizing orderedness (as a measure of both entropy and its enthalpic content) and reproduction. It is bounded very much by the enthalpic curve. Of course, the universe has many pockets of low entropy. Consider a star for example. Eta Carinae represents an extreme measure of orderedness but it does not reproduce. One reason why serious astrobiologists who understand some of the physical sciences and thermodynamics are optimistic about the possibility for simple life on other worlds (meaning prokaryotic life = bacteria) is that prokaryotes represent a fairly low amount of orderedness (their enthalpy content is fairly small). Which means that since we see many pockets of high orderedness in the universe, it seems likely we will find simple life in many places. This is also true in our best detailed estimates of catalytic RNA type processes which are the probable  methods by which life arose around 3.8 billion years ago.  So, as to your concerns, current supercomputer simulations show that rather than being a very, very rare event, abiotic life processes leading to simple cells should actually be pretty common.

 

As to the question Ian is asking about Earth like worlds, that is very much harder to guesstimate. The reason is that once very simple prokarya evolved, the best evidence indicates that the next 3.2 billion years life continued to remain one celled (either as prokarya or as eukarya starting perhaps 1.5 BYA). This makes sense because for life to assume multi-cellular organization, it must make a huge jump up in orderedness. This is thought possible if a star begins putting out more light than in past epochs (the sun grows about 10% more luminous every 900 million years) or an exothermic window is opened (such as the build up of oxygen around 600 MYA). Because of these possible conditions, Earth underwent a very strange and still unexplained explosion of life over a very short period of time (the Cambrian Explosion). (and that has never been repeated since) Life exploded onto the scenes from simple single celled eukarya and simple colony forms to true multi-cellular forms of many different body plans.  Because this represents a much more ordered state, this means the pockets of enthalpy where this exists are likely to be less.

 

And finally, in the quest for Earth like worlds and possible ETs, consider that most university educated professional biologists estimate that 99 to 99.9% of all life that ever lived is now extinct. If we assume the lower bound, then this means that if Earth currently holds about 10 - 15 million species that there have been about 1,200,000,000 species that have lived on Earth. (although, remember, only perhaps 400 to 500 million of them eukarya) (also to be fair, some biologists believe that Earth has held up to 750,000,000,000 species). Since natural selection pressures have only given rise to sapient life once (or possibly a few if you consider dolphins, chimps, etc...) out of hundreds of millions of environments, then we have a very, very strict bound on high ordered intelligent life developing.

 

And that is the reason why many serious professional scientists from the physical sciences who hold a doctorate estimate that bacterial like life out among the stars is probably pretty common. Worlds where you have simple eukarya like colonies may also be fairly abundent. But worlds with six legged horses and intelligent exosaurs might be very rare.


Edited by jayhall0315, 20 February 2015 - 06:57 PM.

  • John Miele, llanitedave, jrbarnett and 3 others like this


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