Is there life in the universe, and if so has it visited Earth?

[baywax]

Well, clay aside, there is a popular theory that ascribes the origin of life to the existence of tidepools.

Here's another origin theory requiring volcanic activity...

Evidence Backs Theory Linking Origins of Life to Volcanoes

The theory that life on Earth began around a volcano, perhaps at the deep-sea vents where molten lava boils through the ocean floor, has been bolstered by the chemical reconstruction of an essential step in the metabolism of living cells.

If the new finding is correct, it means that the recipe for creating life on a newborn planet consists of mostly lethal ingredients and would read something like this: Drop a handful of fool's gold (the mineral iron pyrites) and a sprinkle of nickel into water, stir in a strong whiff of rotten eggs (caused by the gas hydrogen sulfide) and carbon monoxide, heat mixture near the crackle and hiss of a volcano and let simmer for an eon.

Dr. Christian de Duve, a biochemist and Nobel Prize winner who has written on the origin of life, said Dr. Wachtershauser's new work was ''an extremely interesting finding which fits with the idea that life may have originated in a volcanic setting.''

''It stresses the importance of sulfur and iron, which again fits with what we know from biochemistry,'' he said.

Dr. Robert H. Crabtree, a Yale University expert on metals and chemical change, said it was tough to imagine that anyone would discover exactly how life started ''but nevertheless this is an important contribution'' and one that ''could come to be seen as comparable'' with Dr. Miller's if it should prove correct.

http://query.nytimes.com/gst/fullpa...2A25757C0A961958260&sec=&spon=&pagewanted=all

I'm still convinced that, with all the volcanic activity going on in the universe, it is highly probable that life arose at a distant system in the form of viruses or bacteria that are able to withstand the extreme environment of space... and who then populated other planets such as our own by way of bolide incidents and being ejected into interplanetary trajectories.

 

[Pythagorean]

Here's another origin theory requiring volcanic activity...



http://query.nytimes.com/gst/fullpa...2A25757C0A961958260&sec=&spon=&pagewanted=all

I'm still convinced that, with all the volcanic activity going on in the universe, it is highly probable that life arose at a distant system in the form of viruses or bacteria that are able to withstand the extreme environment of space... and who then populated other planets such as our own by way of bolide incidents and being ejected into interplanetary trajectories.

Lightning is a common source of external energy in most generalized abiogenesis explanations. Lightning also happens to be associated with Volcanoes:

http://www.zullophoto.com/Images/G_02828.jpg

 

[baywax]

Lightning is a common source of external energy in most generalized abiogenesis explanations. Lightning also happens to be associated with Volcanoes:

http://www.zullophoto.com/Images/G_02828.jpg

Yeah, Pythagorean, I saw quite a few papers on volcanic lightning forming pre-biotic elements such as amino acids... so far reproducing this phenomenon has only taken place in lab conditions... the conditions are very different when you're in a cloud of volcanic dust, or at -20C etc... .

Biased synthesis of L-amino acids and their polymerisation in repeatably ordered sequences in lightning clouds

Stanley Miller's famous simulation of lightning in a flask containing a reducing mixture of gases produced several amino acids.

But this compact laboratory setup did not simulate all of the conditions in a lightning cloud. If it had done so the result of the experiment might have been even more surprising than it was.

http://www.geocities.com/acgyles/origin.html

The thing about the sub-marine, volcanic bio-genesis is that the temperatures are a scorching 400 C and variations of that as you get away from the flume. Today there are still bacteria that thrive at those high temps. and the number of minerals present in-situ provides a less random availability of materials than a temporary cloud and sporatic lightning. Overall, with the raw materials constantly present at the edges of these underwater plumes and the continuous agitation by heat and currents, a volcanic fissure bathed in sea water sounds like an ideal spot to spawn the nucleotides associated with the RNA or DNA of viral, if not bacterial, life.

 

[B. Elliott]

There is another theory that requires a moon for the appearance of life:

That's what I was postulating with the link I posted. The moon impact scenario 'setting up' Earth on multiple fronts which, all together, allow life to grow and diversify. That's what I meant by asking if we can detect (at least sizable) moons around any of these planets.

 

[CEL]

Here's another origin theory requiring volcanic activity...



http://query.nytimes.com/gst/fullpa...2A25757C0A961958260&sec=&spon=&pagewanted=all

I'm still convinced that, with all the volcanic activity going on in the universe, it is highly probable that life arose at a distant system in the form of viruses or bacteria that are able to withstand the extreme environment of space... and who then populated other planets such as our own by way of bolide incidents and being ejected into interplanetary trajectories.

It must be pointed that viruses are not primitive lifeforms. They are the evolutionary consequence of parasite bacteria that lost their cytoplasm and became simply RNA strings.
Since viruses cannot independently reproduce, they cannot be at the origin of life.

 

[baywax]

It must be pointed that viruses are not primitive lifeforms. They are the evolutionary consequence of parasite bacteria that lost their cytoplasm and became simply RNA strings.
Since viruses cannot independently reproduce, they cannot be at the origin of life.

Perhaps, but they can provide some of the material for life.

 

[DaveC426913]

Perhaps, but they can provide some of the material for life.

I think the point is that you cannot have virii without first having life.

 

[baywax]

I think the point is that you cannot have virii without first having life.

Hi Dave, I am pointing out that viruses can withstand the rigors of space (extreme environments) and may have provided the materials if not the beginnings of life on our planet... rather than life being of terrestrial origin. (ie: has life visited earth?)

Whether life formed on Earth or on another planet... (even Mars)... here is a look at how it may have happened... starting out as a...virus.

"edit:DNA is the molecule responsible for storing and processing genetic information today. In Earth's primeval environmental conditions, RNA was probably more suited for this function, due to its capability to act also as a catalytic enzyme. Some proteins are stable and reliable molecules even in extreme conditions, and under certain circumstances, proteins may play a role in transmitting certain phenotypes that are inherited in a non-Mendelian manner.

The primitive world probably contained both self-replicating RNA molecules and prions, and prions attach easily to nucleic acids, and also fold and cause other proteins to fold in the same way. Consequently, a capsid could form from prion protein, enclosing the RNA, and perhaps creating the first RNA virus. A capsid originating from prion proteins would be a versatile and effective protection to RNA and could also explain some characteristics of virus self-assembly that are not well understood."

http://www.ncbi.nlm.nih.gov/pubmed/...ez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum

So far it appears that the self-assembly of viruses is "not well understood" so I would not go as far as to rule out viruses as relying solely on a host to survive or even reproduce.

 

[DaveC426913]

Hi Dave, I am pointing out that viruses can withstand the rigors of space (extreme environments) and may have provided the materials if not the beginnings of life on our planet... rather than life being of terrestrial origin. (ie: has life visited earth?)

Well yes, but that's simply pan-spermia.

IMO, saying that "the origin of life is that it was seeded from somewhere else" simply moves the question one step back: so where is the actual the origin of life?

 

[baywax]

Further to this idea of our planet being seeded by life that formed on another planet, I'm beginning to wonder if Mars was not somehow involved in the development of life on Earth.

For instance, if life began on Mars before it did on Earth, the relative proximity boosts the chance of a "pollination" by way of viral infection across the distance of space from Mars to Earth. It is obvious that Mars has experienced a major collision with a large body and perhaps that was the catalyst that spewed enough of life's material into Earth's primordial soup which was, no doubt, ripe and ready to nurture the development of life, on Earth.

 

[baywax]

IMO, saying that "the origin of life is that it was seeded from somewhere else" simply moves the question one step back: so where is the actual the origin of life?

Probably in another thread.

 

[baywax]

However, it is a perplexing question to ask where and when did life first begin to emerge in the universe. And its not so far off the topic of this thread to ask this because, one would have to know these things in order to know when and how life "has visited Earth".

We can consider the time period we have to work with... 14 billion years... and the amount of material available to form life with... 10 to the power of 9... we still have to come up with the period during which life could form in the universe with proper conditions and relative stability for continued evolution etc...

I'm not the best at statistics and modeling but PF is probably the right place to ask this question..."what is the earliest period in the universe's development that life could begin to develop and where would that have been?"

 

[shamrock5585]

Reading some of these posts and articles i kind of came up with a very loosely based theory, maybe someone can even elaborate. The big bang is originally thought that there was no matter and just all the energy in the universe were combined into an infinitely small thing or even something of no size (all the mass was originally energy). Well when the big bang occurred the forces and energy were released and matter randomly formed from the energy and maybe in all the chaos and randomness life spuratically occurred and drifted for a long time until it reached a place it could flourish... NASA says that lichen can survive in space, who knows if original microscopic lifeforms could have and were just deposited on random asteroids or rocks when matter formed from the energy after the big bang... so our origins somehow landed on Earth and over billions of years flourished, maybe other forms of the same origins landed somewhere in another galaxy as well... so then we would even be very distantly related to lifeforms in other galaxies!

 

[DaveC426913]

... maybe in all the chaos and randomness life spuratically occurred ...

Simply hand-waving the issue is not the same as addressing it.

How did life get started?

 

[baywax]

Simply hand-waving the issue is not the same as addressing it.

How did life get started?

Here's one theory...

Odd Rock Structures Could be Earliest Signs of Life
By Ker Than, LiveScience Staff Writer
posted: 07 June 2006

They resemble upside-down ice cream cones or egg cartons, but a new analysis suggests that the odd sedimentary structures found in Western Australia are among the earliest signs of life on the planet.

Called "stromatolites," the structures are believed to be about 3.4 billion years old. Since they were first described nearly 30 years ago, scientists have see-sawed between attributing them to the work of ancient microbes or hydrothermal vent activity.

But in a new study detailed in the June 8 issue of the journal Nature, Australian researchers argue that the shapes of the stromatolites are too complex and diverse to have been formed by physical processes.

http://www.livescience.com/environment/060607_stromatolites.html

(edit)The organism that formed the "stromatolites" didn't necessarily develop on this planet... or... what they have evolved from didn't necessarily originate on Earth. But, if the sedimentary reading of 3.4 billion years old is correct they are probably Earth's own lifeform.

The creators of the stromatolites, if they were a life form, are a good example of how easily life can happen in a volcanic environment. According to modern Geology, Earth was only formed 600,000,000 years before the stromatolite came into being. This should indicate how easily life is constructed and what kind of environment is required to have it happen (assuming they are a life form).

editII But this doesn't explain the beginnings of life as in the formation of a structure that reproduces itself and has a membrane that protects organelles and fluids inside. I'll be back.

 

[CEL]

Reading some of these posts and articles i kind of came up with a very loosely based theory, maybe someone can even elaborate. The big bang is originally thought that there was no matter and just all the energy in the universe were combined into an infinitely small thing or even something of no size (all the mass was originally energy). Well when the big bang occurred the forces and energy were released and matter randomly formed from the energy and maybe in all the chaos and randomness life spuratically occurred and drifted for a long time until it reached a place it could flourish... NASA says that lichen can survive in space, who knows if original microscopic lifeforms could have and were just deposited on random asteroids or rocks when matter formed from the energy after the big bang... so our origins somehow landed on Earth and over billions of years flourished, maybe other forms of the same origins landed somewhere in another galaxy as well... so then we would even be very distantly related to lifeforms in other galaxies!

Unlikely! Immediately after the Big Bang the only elements existent were hydrogen and helium. When the first stars formed they started to fuse hydrogen and helium in order to form other elements from lithium to oxygen.
Elements heavier than oxygen can only be formed in the explosion of supernovae. So a few hundred million years were needed in order to have the bricks for life.

 

[shamrock5585]

Unlikely! Immediately after the Big Bang the only elements existent were hydrogen and helium. When the first stars formed they started to fuse hydrogen and helium in order to form other elements from lithium to oxygen.
Elements heavier than oxygen can only be formed in the explosion of supernovae. So a few hundred million years were needed in order to have the bricks for life.

true... and interesting... what i was suggesting was that life could be one of the basic building blocks of the universe and that, it as a whole, like energy and matter cannot be created or destoryed... like i said it is very loosely based and unlikely... just throwin stuff out there

 

[CEL]

true... and interesting... what i was suggesting was that life could be one of the basic building blocks of the universe and that, it as a whole, like energy and matter cannot be created or destoryed... like i said it is very loosely based and unlikely... just throwin stuff out there

I am not sure, but I think it is against the rules of the forum to throw unsubstantiated ideas around.

 

[shamrock5585]

isnt the main question an unsubstantiated idea in the first place? think before you speak!

 

[DaveC426913]

isnt the main question an unsubstantiated idea in the first place? think before you speak!

The main question was not a claim. Yours is.

And there's no need to be conscending.

 

[shamrock5585]

i love this forum but it really pisses me off when you say something and people complain and whine... i stated specifically it is VERY loosely based theory based on me just thinking... i didnt claim anything i was just stating that MAYBE it COULD be POSSIBLE.

 

[DaveC426913]

i love this forum but it really pisses me off when you say something and people complain and whine... i stated specifically it is VERY loosely based theory based on me just thinking... i didnt claim anything i was just stating that MAYBE it COULD be POSSIBLE.

well, ghosts & faeries "could be possible"...

There are plenty of fora where "just throwin' stuff out" is encouraged; this just doesn't happen to be one of them. Nobody's insulted you, they're just pointing out that a line was crossed and it's time to backtrack. There's little call for being pissed off about it and no call for accusing people of "complaining and whining". You did agree to it when you signed up.

 

[shamrock5585]

my post complied completely with the main question... life and earth... i was suggesting that maybe life didnt originate on Earth in the first place... i figured i could post a possible idea seeing as this is in the skepticism and debunking area of the site but as usual we end up going off topic because instead of taking the post for what it is or even skipping over it if you don't like it, youd rather complain.

and furthermore... i find it kind of contradicting in the rules anyway...

"There are many open questions in physics, and we welcome discussion on those subjects provided the discussion remains intellectually sound. It is against our Posting Guidelines to discuss, in most of the PF forums, new or non-mainstream theories or ideas that have not been published in professional peer-reviewed journals or are not part of current professional mainstream scientific discussion."

how do you discuss open questions that have not been answered in physics without suggesting answers? scientists usually start with a hypothesis do they not?

 

[baywax]

This may help with figuring out how life started in the universe. If it visited Earth before life had a chance to start here it will be very hard to prove because, in the mix, the details get kind of lost...

Abiogenesis

In the natural sciences, abiogenesis, the question of the origin of life, is the study of how life on Earth emerged from non-life. Scientific consensus is that abiogenesis occurred sometime between 4.4 billion years ago, when water vapor first liquefied,[2] and 2.7 billion years ago, when the ratio of stable isotopes of carbon (12C and 13C), iron (56Fe, 57Fe, and 58Fe) and sulfur (32S, 33S, 34S, and 36S) points to a biogenic origin of minerals and sediments[3][4] and molecular biomarkers indicate photosynthesis.[5][6] This topic also includes panspermia and other exogenic theories regarding possible extra-planetary or extraterrestrial origins of life.[7]
Abiogenesis is a limited field of research despite its profound impact on biology and human understanding of the natural world. Progress in this field is generally slow and sporadic, though it still draws the attention of many due to the eminence of the question being investigated. Several hypotheses have been proposed, most notably the iron-sulfur world theory (metabolism first) and the RNA world hypothesis (genetics first).[8]

http://en.wikipedia.org/wiki/Origin_of_life

PS. It looks as though the Earth is thought to have formed and become volcanic more like 4.4 billion years ago according to this article. That would mean that any organisms capable of forming Stromatolites would have had around 1 billion years to evolve.

My estimation is that life (in the entire universe) began forming soon after the first Supernovae were starting to happen during the development of the universe... if what CEL says is true about the diversity of elements being formed by these super explosions.

I could go on and on about this but let me just say one or two things about life's origin.

I believe it would have been a step by step process. So that you'd see the chemicals brought together that would supply the basis for a metabolism. Then you'd see very primitive development of life forms... perhaps unknown to us today or only known as "organelles". These primitives would find it easier to survive in groups and perhaps in capsules of the chemical mix that had come together... forming a "proto-metabolism". With a non-biological membrane somewhat protecting the primitive formations of "life" (viral or pre-viral structures) in a solution that supported these structures, the prion theory seems to come in handy where prions and nucleotides begin to fold in an order that soon give rise to a primitive RNA or VRNA. At some point a biological membrane is developed, if not sporatically formed... mimicing the non-biological membrane encapsulating this odd arrangement. This would give rise to a primitive cell, with replicating capabilities due to the nature of the prion/nucleotide relationship and the motility made available either by volcanic current, water movement or heat agitation. Later on we see the organelles as parts of the cell when they were probably individual and primitive life forms of their own...which developed out of abiogenesis. With this in mind it is worth pointing out that the mitochondria organelle of each cell has a set of its own DNA apart from that of the nucleus of each cell.

 

[BoomBoom]

"what is the earliest period in the universe's development that life could begin to develop and where would that have been?"

I find this a very interesting question.

If the first stars were all hydrogen and helium based, would it require at least a 3rd generation of stars to create the elements necessary for life? Or could a supernova from a star with elements no heavier than helium create them?

It could very well be that we are among the first generation of life in the universe when taking into account the incredible amount of time required for formation of stars, the life-span of stars, and the amount of time for supernovas to re-condense into new stars and planets...not to mention the billions of years required for life to evolve. (if the universe is really only 13 billion years old that is...)

If that is the case, then I find it highly unlikely that we could have ever been visited by some being from another solar system. This is, of course, assuming that traveling those distances is even possible in a reasonable time-span...which also seems highly unlikely.

However, I feel quite certain that life is everywhere throughout the universe...though we will most likely never meet any of them (at least not in our lifetimes).

 

[baywax]

However, I feel quite certain that life is everywhere throughout the universe...though we will most likely never meet any of them (at least not in our lifetimes).

Besides, what do you say to a slime mold from N1595/8?

 

[DaveC426913]

my post complied completely with the main question

You supposed that life could neither be created nor destroyed, that it was some basic building block. This is ... well, more than wild speculation, it's woo-woo-ism. Much of the rhetoric that follows seems to be about massaging a wounded ego.

Let's get back to science.

 

[Ivan Seeking]

true... and interesting... what i was suggesting was that life could be one of the basic building blocks of the universe and that, it as a whole, like energy and matter cannot be created or destoryed... like i said it is very loosely based and unlikely... just throwin stuff out there

That is not discussing the evidence. You are suggesting a new concept that has no supporting evidence - in effect you are suggesting that there is a life force fundamental to existence. If we ever measure such a force or can describe it mathematically, then we can talk about it, but without any experimental evidence or theoretical model, we might as say that life results from magic. In other words, hypotheses are based on logical extrapolations of the evidence, and not on ideas that have no supporting evidence.

We are done with this idea. Let's move on.

 

[CEL]

I find this a very interesting question.

If the first stars were all hydrogen and helium based, would it require at least a 3rd generation of stars to create the elements necessary for life? Or could a supernova from a star with elements no heavier than helium create them?

It could very well be that we are among the first generation of life in the universe when taking into account the incredible amount of time required for formation of stars, the life-span of stars, and the amount of time for supernovas to re-condense into new stars and planets...not to mention the billions of years required for life to evolve. (if the universe is really only 13 billion years old that is...)

If that is the case, then I find it highly unlikely that we could have ever been visited by some being from another solar system. This is, of course, assuming that traveling those distances is even possible in a reasonable time-span...which also seems highly unlikely.

However, I feel quite certain that life is everywhere throughout the universe...though we will most likely never meet any of them (at least not in our lifetimes).

Very massive stars, exactly the ones who turn supernovae, are short lived. An extremely huge star can go supernova in a few hundred million years. So, the building blocks of life were possibly present in the first billion years of the universe.
Of course, the presence of the chemicals of life does not mean that life has existed for so long time.

 

[baywax]

Very massive stars, exactly the ones who turn supernovae, are short lived. An extremely huge star can go supernova in a few hundred million years. So, the building blocks of life were possibly present in the first billion years of the universe.
Of course, the presence of the chemicals of life does not mean that life has existed for so long time.

No it doesn't. There would have to be proper conditions to allow life to develop. I remember a thread here on PF where a link pointed out how just within our galaxy there is a zone where conditions are stable enough to support the development of life. Let me try to find a similar link...

Galaxy's life zone pinpointed

Australian scientists have helped narrow the search for extraterrestrial life.

Researchers from Melbourne's Swinburne University of Technology have identified the part of our galaxy where Earth-like planets capable of harbouring life are likely to flourish.

It is called the Galactic Habitable Zone - an area where rocky planets not only form easily, but can safely harbour life away from deadly hazards such as exploding stars.

The ring-shaped region contains about 10 per cent of the galaxy's 200 billion or so stars and, aptly, includes our own sun.

http://www.theage.com.au/articles/2004/01/01/1072908849778.html

Now, if we extrapolate the conditions in this zone... with few exploding stars, fewer astroid belts and gamma radiation or whathaveyou... to include the entire universe at an early stage... we may be able to pin-point at what period/stage/area during the past development of the universe that life had a chance to first emerge from the universe's younger state.

Here's another quote from the same article:

"Our Milky Way galaxy is home to hundreds of billions of stars but until recently astronomers could only guess as to how many are hospitable for the development of complex life," said co-author Dr Charles Lineweaver from the University of NSW. "What we have done for the first time is to quantify carefully where complex (animal) life is likely to exist."

 

[Pythagorean]

However, it is a perplexing question to ask where and when did life first begin to emerge in the universe. And its not so far off the topic of this thread to ask this because, one would have to know these things in order to know when and how life "has visited Earth".

We can consider the time period we have to work with... 14 billion years... and the amount of material available to form life with... 10 to the power of 9... we still have to come up with the period during which life could form in the universe with proper conditions and relative stability for continued evolution etc...

I'm not the best at statistics and modeling but PF is probably the right place to ask this question..."what is the earliest period in the universe's development that life could begin to develop and where would that have been?"

This brings up another question that has always swam around when considering abiogenesis, too. Did life necessarily have to start in a single place?

Could there have been a period in a universe that was very conducive to the formation of life somewhat independent of space? Of course, there would still be a distribution of regions where it was more or less probable, but why is the question always asked from the standpoint that there's only one place of origin?

ADDENDUM:

Of course this doesn't mean that all these 'origin zones' were conducive to long-term development and evolution of their host life forms. Apparently (at least in the carbon-based model) we need something like Earth for that, where volcanoes and earthquakes serve to distribute nutrients about the surface of the planet.

 

[BoomBoom]

Very massive stars, exactly the ones who turn supernovae, are short lived. An extremely huge star can go supernova in a few hundred million years. So, the building blocks of life were possibly present in the first billion years of the universe.

Thanks Cel.
So, now how long would it take for those heavier elements to condense into new solar systems and the planets to cool to the point where abiogenesis could begin?

Then we can tack on a few billion years on top of that for life to evolve...

I'm just trying to get a sense of what the earliest possible point at which life could have evolved in the age of the universe.

 

[baywax]

Then we can tack on a few billion years on top of that for life to evolve...

Actually, with Earth being around 4.4 billion years old and the stromatolites that are thought to have been formed by some form of algae at around 3.5 billion years... it looks as though life only requires about a billion years to get to a point where it is mobile and constructive. This would mean that by about 500 million years into Earth's development there could have been a rudimentary form of life developed and evolving on earth.

In other words, with the proper conditions, you don't need "billions" of years for life to develop. This would dramatically push back the date of the first "emergences" of life in t he universe's "habitable zones".

(The plurals are for Pythagorean)

 

[BoomBoom]

This brings up another question that has always swam around when considering abiogenesis, too. Did life necessarily have to start in a single place?

If we really believe (well, many of us) that life forms so easily given the proper elements and conditions, then why is it that many assume it only happened once and all life on Earth came from a single source? If this is the case, then it should be happening all the time here on Earth IMO.

Craig Ventor is doing his ocean sequencing project where he is taking random samples from waters all around the world and sequencing the DNA recovered and I heard they are discovering incredible amounts of new genes not found in any other species (I can hunt down a link if required). Much of the microbial life of Earth could have come about more recently.

If this is not the case, and all life on Earth did come about by some freak accident, then I'd be much more skeptical about it existing elsewhere.


Ok, here's one article http://www.genomenewsnetwork.org/articles/2004/03/04/sargasso.php"

In the Sargasso Sea, they found 1800 species of microbes, including 150 new species of bacteria, and over 1.2 million new genes. Although they don’t know what most of these genes do, the research is a first step to understanding more about life in the Sargasso Sea and the larger ocean.

 

[BoomBoom]

This would mean that by about 500 million years into Earth's development there could have been a rudimentary form of life developed and evolving on earth.

In other words, with the proper conditions, you don't need "billions" of years for life to develop.

True, but I was putting this in the context and frame of reference of the original poll question, "...and if so, has it visited earth?".

For a life form to develope far enough to engage in space travel and travel to distant solar systems, I think it would be safe to assume that would take billions of years. In other words, how soon in the age of the universe could "intelligent" life have emerged?