Coffee with Dr. Fermi

by Paul Gilster on April 25, 2012

I cannot live without good coffee, and that means fresh beans ground right before brewing, and either manual drip or French press extraction. Every morning after publishing Centauri Dreams I make a couple of cups and go out on the deck to rest my eyes and ponder the state of things before hitting the books for background research in the afternoon. Various thoughts about what to write next always come to me, but yesterday I mused about Enrico Fermi, the legendary Italian physicist who, among so much else, left us with a great unanswered question: Where are they? If it’s so easy for the universe to make intelligent species, why is SETI coming up so short?

Where are they indeed? The day was gorgeous, the air filled with birdsong, temperatures in the mid-60s and a mild breeze. What better setting to be immersed in, thinking about where life emerges and when? I imagined Fermi sitting across from me with a cup of my Costa Rica Tres Rios in his hand, wondering what he might say about the fuss his question has caused over the years. I can almost hear him saying, “Look, it wasn’t serious. It was just a throw-away comment over lunch. I didn’t even think about it.” And then I imagine him gazing out over the hillside and wrinkling his brow. “But you know, it really is an interesting question, isn’t it? I mean, really!”

Image: Enrico Fermi, with no coffee in sight. Credit: AIP Emilio Segrè Visual Archives.

Alpha Centauri: The Age of Things

Obviously I’m putting words in the man’s mouth, but that’s the thing about the Fermi paradox: It keeps coming around. And in one respect it seems particularly disturbing. If the Sun is in the vicinity of stars that are far older than it is, that would give planets around those stars far more time to produce their own living species and far more time for intelligence and technology to emerge. We can think about these things in terms of Alpha Centauri, the subject of these last few posts, because based on recent studies, these stars are much older than our Sun.

How old? To answer the question, the go-to people are Patrick Eggenberger (Observatoire de Genève) and colleagues, who in 2004 produced a paper on the matter that ran in Astronomy & Astrophysics (citation below). A wide range of ages has been posited for these stars over the years, ranging from as little as 2.71 billion years up to well over 6 billion — the paper runs through the previous analyses — but Eggenberger and team go to work with the latest astrometric, photometric, spectroscopic and especially asteroseismic data to reach a strong conclusion: “The global parameters of the α Cen system are now firmly constrained to an age of t = 6.52 ± 0.30 Gyr.”

6.52 billion years, plus or minus 300 million. Now we can think about the Sun’s age, thought to be about 4.57 billion years, and you can see that Alpha Centauri A and B have a 2 billion year jump on us. So does Proxima Centauri, because as we saw yesterday, Greg Laughlin and Jeremy Wertheimer made a convincing case that Proxima is indeed bound to Centauri A and B, and thus probably originated in the same molecular cloud that produced its companions.

I think I’m going to pour Dr. Fermi another cup of coffee about now, because that 2 billion years provides ample time for interesting things to develop given an astrobiologically friendly planet. Long-time Centauri Dreams readers will also know that Charles Lineweaver (Australian National University) has studied the galactic habitable zone and the distribution of stars in the Milky Way by age, finding that 75 percent of the stars in an annular region between 7 and 9 kiloparsecs from galactic center, where life should be possible, are older than the Sun.

Alpha Centauri, using the age estimates of Eggenberger and colleagues, turns out to be fairly average, for Lineweaver says “…the average age of Earths around Sun-like stars is 6.4 ± 0.9 billion years.” He thus thinks that planets around other stars in the galactic habitable zone should be, on average, 1.8 billion years older than our planet, about the same difference as between our Sun and Alpha Centauri. And this is only an average. Milan Ćirković (Astronomical Observatory of Belgrade) notes that there should be inhabited worlds in our galaxy as much as 3 billion years older than our own. So we have on our own doorstep (in astronomical terms) a triple star system that dramatically points to the time frames life has had available to develop civilizations.

Proxima’s Deadly Flares

At this point Dr. Fermi might well take me to task (at least, the imaginary Dr. Fermi who is not only still with us, but completely up to speed on red dwarf studies). I think he would point out that Proxima Centauri is an active flare star with loads of coronal X-ray emission, not exactly a hospitable place for life. We can imagine a calmer, much older Proxima Centauri eventually settling down into a benign middle age, but imagining that also makes us realize that while Alpha Centauri A and B may have provided the opportunity for intelligent life to develop long ago, Proxima may be the most marginal of the Centauri possibilities as of now.

Red dwarfs live, depending on their mass, for trillions of years, so we shouldn’t despair about the future — and we can always ponder whether any kind of adaptive mechanism might rescue astrobiology even in so hostile a place. But as a home for human colonists of the first interstellar mission, any conceivable planet of Proxima Centauri gives way to what we hope to find around Centauri A or B, a rocky world in a habitable zone we might be able to survive within.

Two Charles Lineweaver papers are in play here, the first being “An Estimate of the Age Distribution of Terrestrial Planets in the Universe: Quantifying Metallicity as a Selection Effect,” Icarus 151 (2001), pp. 307-313 (full-text). The second is “The Galactic Habitable Zone and the Age Distribution of Complex Life in the Milky Way,” Science Vol. 303, No. 5654 (January, 2004), pp. 59-62 (abstract). The Eggenberger paper is “Analysis of alpha Centauri AB including seismic constraints,” Astronomy & Astrophysics Volume 417, Number 1 (April I 2004), pp. 235-246 (abstract).

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{ 129 comments }

Ronald May 2, 2012 at 4:56

Rob, Eniac, ignorant question with regard to CH4 and NH3: what planetary conditions are required for an atmosphere largely consisting of CH4 and NH3? In our solar system we find such atmospheric abundance only in the gas giants and ice subgiants.
Does it require great gravity, or also low temperature?
If the latter is the case, then such a very low temp environment would probably also imply very low evolutionary rates.

ljk May 2, 2012 at 12:24

“I for one welcome our new Artilect Overlords. I ‘d like to remind them that as a trusted space buff and future/alien optimist, I can be helpful in rounding up others to toil in their hyperlattice cyberspace matrixes.”

Original Simpson quote here, for those who may miss the joke:

http://itre.cis.upenn.edu/~myl/languagelog/archives/000399.html

Ole Burde May 2, 2012 at 13:21

Here is the answer to the question about an alternative kind of photosyntesis producing molecular H2 instead of O2 , and perhabs thereby making an alternative reducing life-ecology sustainable :
“Though photosynthesis of higher plants, algae and cyanobacteria produces oxygen, there are conditions under which this type of photosynthesis operates under hypoxic or anaerobic conditions. In the unicellular green alga Chlamydomonas reinhardtii, this condition is induced by sulfur deficiency, and it results in the production of molecular hydrogen”
(A. Hemscheimer , RU )
So , it seems that the molecular mashinery of DNA can learn to do almost anything ….

Eniac May 2, 2012 at 18:35

Ronald:

what planetary conditions are required for an atmosphere largely consisting of CH4 and NH3? In our solar system we find such atmospheric abundance only in the gas giants and ice subgiants.
Does it require great gravity, or also low temperature?

Primarily, what is needed is an oversupply of hydrogen. This can be caused by high gravity or low temperatures. Either one alone would be sufficient. Our best bet therefore would be super-Earths in the habitable zone.

Wojciech May 2, 2012 at 18:52

“No reason is needed. If colonization of unsettled systems happens just a little bit more often than complete extinction in settled systems, exponential growth will fill the galaxy eventually, with or without intent. Bacteria are not trying to fill a Petri dish, and yet, they do.”
Bacteria are not self-aware(hence unlike intelligent beings need no reason), and Galaxy is not a Petri dish. In fact Galaxy and space in general, is a very, very hostile place to life(unlike said Petri dish). Human species doesn’t engage in exponential growth, in fact many advanced technological societies go the opposite way with less reproduction and more nature preservation. The ironic thing is that the technologies that would allow us to cross the deadly gulf of space, would probably mean also the end of need for much
colonization(even if it would be possible). For example being able to travel stars on a proble in a form of virtual reality would also mean that you don’t need much space to live in. Having extremely long life span means also having less children and so on. Just two examples of course. Our increasing technological knowledge, that gives the potential for interstellar travel also gives hints of possibility of post-biological future. And this is not a future in which we reproduce like rabbits ;) Furthermore we still know little about physics, dark matter, dark energy. Perhaps there are levels of reality that we still haven’t grasped which would completely change our

“Each star system will be its own world, making decisions about colonization or anything else on their own, without first asking for permission or even opinion from some “authority” 20 lightyears away. It is likely that even within individual settled systems there will be multiple independent “civilizations”.

Even on Earth we still have separate nation states, although in many ways we have become a single civilization, due to our forced proximity. As a consequence of this diversity, if there is even just a tiny chance for colonization to happen in a given society, it will happen for sure in aggregate, particularly as the number of civilizations grows.”

That’s a very traditional and conservative vision of future. Nation states in civilization where the very concept of human is likely to be just as relevant as choice of shoes to us? I am afraid the reality of space and probable civilizations doesn’t seem close to Star Trek or Star Wars. It is far more alien
and exotic, if you look at consequences of technologies which would also enable star travel. It might very be that each individual will be as nation today.

“settled systems”-why would anyone want to settle systems that are hostile and require immense resources to reach and colonize? Remember-sentient beings are bacteria :) And as to society-that is the past of primates, what might constitute society to being that shape their genes and body as easily as we shape our computer avatars might be very very different(and this is a prospect of 1000 years, who knows what awaits in million?)

“You say we are retreating from formerly settled land. Can you give examples?”
Sure

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

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

As to ban on contact with less advanced societies-India has such regulations regarding Sentinelese people. There have been violations, but Indian government is not a galactic civilization with its possibilities for enforcement ;)

To sum up. Exponential growth is not a certainty and current trends indicate a direction into reducing extent of settlement, but with more density and more micro scale development. The same level of technological advancement making interstellar travel possible could at the same time reduce our need to colonize or to reproduce on large scale. The human condition in couple of thousand years is beyond our comprehension and likely will mean abandoning our biological needs and limits-hence I don’t
think we can be certain that we will colonize galaxy-either due to lack of need or opening up of new perspectives with new discoveries in physics. Travel? Research? Maybe. But trillions of trillions humans like us living in cities across all the hostile space? Very farfetched and has little reason in the first place. In any way our descendants will be far, far removed from our current species and probably post-biological.

That is not to say there is no possibility of some recognizable organizational entities colonizing local clusters of stars, regions within a couple of hundreds of years(the same for other species). But considering the distances involved, time, hostility of space and technology needed, I wouldn’t bet on them colonizing galaxy before falling to some Extinction event, ennui, or abandoning need for such extensive colonization altogether. And I wouldn’t, really wouldn’t bet on anything like Star Trek or “Galactic Council”. If other races exists they are on levels either unimaginable to us or are yet to develop their first stone tools.

In any case: watch the skies! ;) Our new telescopes could detect not only life, but mega-scale engineering as well. It is probably more efficient way to search for alien life and civilization than radio signals.

Wojciech May 2, 2012 at 18:58

” The kind of entity that would colonize other stars would very likely be technologically enabled to make a good living from nothing more than a few asteroids or a small moon, plus the light of the star”

That kind of entity would then lack the need for any rapid growth at all(plus despite this, surviving some conditions might be problematic anyway). Growth for the sake growth is after all the ideology of cancer cell. A branch of a civilization which would act this way, might be treated accordingly-either by its kin, or whatever is slumbering since billions of years in the dark void beetween the stars, patiently observing how life and universe develops on its own-without upstart radicals trying to erase uniqueness in the galaxy ;)

Rob Henry May 2, 2012 at 19:54

Eniac says “The somewhat darker possibility is that our generation is the last before the coming robot revolution. Although, you could ask, why are we not robots, then?”

For the purpose of allowing a valid statistical argument the answer is simple. Those robots, no matter how sentient, are strangely incapable of asking “how likely is it that I am here at this point in history”

Rob Henry May 2, 2012 at 23:29

Avatar, even though statistics is often comparatively easy maths, it came late it history because it runs so counter to human intuition. Note how you asked how generations before of us would have thought of the problem, but probably never even contemplated how this is exactly balanced by how generations after us (and are thus not part of our natural thinking).

Rob Henry May 3, 2012 at 0:18

Ronald, your comment on the effect of population growth brings up questions as to what is the optimum population size that an intelligent civilisation may have aspirations to achieve. One prominent physicist (I have forgotten who) once pointed out that a world population greater that any one individual could ever get to know in a lifetime was wasteful. So if purely social considerations dictate such a goal, and declining fertility in the First World is only arrested once this is reached, that would help, but the problem is still big.

Rob Henry May 3, 2012 at 0:56

Ronald, I would add this to Eniacs comments. CH4 and NH3 are constantly broken down by UV light. CH4 is very much easier to replenish geochemically or biochemically. I fear that only a trace of NH3 would exist it all but gas giants, where turnover of material from areas of very high pressure and temperature helps. I was thinking high CH4, H2 and N2, with just traces of NH3, much (most?) of it fixed by lightening.

Eniac May 3, 2012 at 2:04

Wojciech:

Growth for the sake growth is after all the ideology of cancer cell.

More than that, it is the ideology of life. Always has been, and I do not agree that sentience will somehow put an end to that.

Your islands have not been abandoned, they have populations in the thousands and modern infrastructure. Your Sentinelese are probably in their free time discussing the relative merits of iPhone vs. Android.

One time you say growth will not happen because of difficulty, and then you say it will not happen for lack of need. History and biology both show that life will spread despite difficulty, and that it will grow even faster when well supplied. Your only remaining possible point is that this may radically change in the future, but there is scant evidence for that and I just don’t think so.

Eniac May 3, 2012 at 9:41

For the purpose of allowing a valid statistical argument the answer is simple. Those robots, no matter how sentient, are strangely incapable of asking “how likely is it that I am here at this point in history”

Strange, indeed. You would think any sentient being with an interest in statistics would have such thoughts, robot or not. Perhaps we are the robots, after all.

Wojciech May 3, 2012 at 15:04

“More than that, it is the ideology of life. Always has been, and I do not agree that sentience will somehow put an end to that.”
Easily disproven by existance of sterlization treatment, voluntary extinction movement, falling birth rates in developed world and countless people who decided not to have children.
Also:biological life. Something that civilizations with ability to colonize other stars will transcend, and as such also its needs.

“Your islands have not been abandoned, they have populations in the thousands and modern infrastructure.”
Actually Stewert Island has only 400 people. I am afraid you didn’t even bother to read the link :) And the Marquesas have never recovered to population of over 100.000, recentely the population has experienced decline as well.
“Your Sentinelese are probably in their free time discussing the relative merits of iPhone vs. Android.”
I am afraid you are now grasping at inventing things and claims that are unproven. The Sentinelese are one of the most isolated people in the world and remain largely untouched by civilization. Most of the time they reject any contact as well.

“One time you say growth will not happen because of difficulty, and then you say it will not happen for lack of need”
Growth will not happen due to difficulty for biological forms to colonize galaxy, and lack of need will stop it for post-biological descendants of those form who will have the ability to do so.
You missed that crucial difference between the two.

Avatar2.0 May 3, 2012 at 15:12

Rob Henry
“Avatar, even though statistics is often comparatively easy maths, it came late it history because it runs so counter to human intuition. Note how you asked how generations before of us would have thought of the problem, but probably never even contemplated how this is exactly balanced by how generations after us (and are thus not part of our natural thinking)”

Rob Henry, the probabilities are the same, regardless of whether one knew/knows how to calculate them or not or whether one thought/thinks about them or not.

As per Gott’s argument, every previous generation in history won the proverbial lottery, without fail – they were not the peak of a smaller Bell curve (as they were most likely to be, as per the argument).
The generations coming after us only make the distribution of the previous generations’ position on the ever larger Bell curve more improbable, not less.

Of course, no two generations in history were alike, and many were quite different from their predecessors. That’s especially true about the last hundreds of years.
And Gott’s argument relies upon all generations being equal – a condition not fulfilled. Thus, it fails when applied to human history.

Ole Burde May 3, 2012 at 16:38

If it should turn out that life happened only once in our galaxy , we would probably get more and more clear statistical evidence for it in the near future, and the case could be “without reasonable doubt” inside the next 30 years. If that should happen , mankind will face a filosophical question which might change the nature of religion and other forms of etics : should we consider it a moral obligation to spread life to other worlds ? if you believe that existence has a purpose or direction , then the purpose or direction of evolution must be to produce aspecies capable of breaking out from this single planet . Not to spread its own genes , but to seed life in general all over the place …

Eniac May 3, 2012 at 23:02

Easily disproven by existance of sterlization treatment, voluntary extinction movement, falling birth rates in developed world and countless people who decided not to have children.

For every general principle you can find isolated exceptions. Even in the best Petri dish, some bacteria will die, to be overrun and eaten by others. The things you mention prove nothing, especially not if you consider that world population is still growing robustly. And then, population numbers are not what matters here. What matters is spread in range. No population has ever stayed in a limited space by choice. Modern humans covered the Earth in a few ten thousands of years, starting out from Africa. On foot, no less. Well, except for the occasional boat….

You are right about the Sentinelese, they probably do not have cell phones, yet. However, they are also not a good example of people intentionally left to their own devices. You can see this in the YouTube video where they are filmed busily picking up large numbers of coconuts dropped off for them by a fun-loving bunch of boaters. Can cellphones be far behind? In any case, the Sentinelese are a curiosity, hardly representative of our treatment of “lesser” cultures. Of which there are, of course, not many left.

lack of need will stop it for post-biological descendants of those form who will have the ability to do so.

Their is never a lack of need to go out and explore the world. I cannot imagine how you envision this. A bunch of electronic entities all hunched together on an asteroid or planet turned nanosupercomputer, engaging in virtual reality gaming and social networking, without ever wanting to send probes and seeds to other places that they know exist and are able to reach? Give me a break.

At the very least, there is a good chance that these are going to be computer geeks. Everyone knows that computer memory has to double about once a year, or else the latest games won’t run. Eventually, even the most sophisticated nanosupercomputers will run out of resources to keep this up, and finding places with fresh resources will become number one priority…

Eniac May 3, 2012 at 23:16

Rob:

Ronald, your comment on the effect of population growth brings up questions as to what is the optimum population size that an intelligent civilisation may have aspirations to achieve.

While this is an interesting question, it has no bearing on the matter at hand. If civilizations want to be small, it just means there will be more of them. Size does not matter. What matters is the tendency to go out and explore, the desire to find and occupy new territory. Colonists are interested in getting away from their “civilization”, not to increase its size.

Avatar2.0 May 4, 2012 at 3:14

Wojciech
““More than that, it is the ideology of life. Always has been, and I do not agree that sentience will somehow put an end to that.”
Easily disproven by existance of sterlization treatment, voluntary extinction movement, falling birth rates in developed world and countless people who decided not to have children.”

Eniac talks about the ideology of ‘life’, not individuals.
At present, humanity is more populous than at any other time in history – and spread over more of the Earth.
Non-sentient life also followed the imperative to multiply and spread.

Indeed, life evolved to accomplish these purposes (anatomically, instinctually).

As counterarguments, you only have exceptions (and not large-scale ones, at that). Hardly enough to ‘disprove easily’ Eniac’s point.

Ronald May 4, 2012 at 5:08

@Ole Burde May 3, 2012 at 16:38;

Very interesting and relevant point. But do you mean life in general, i.e. all/any biological life, including microbes (which are most likely the most common life to be found anywhere anyway). Or higher life? Or intelligent life?
Please elaborate, because detection may be different, as well as the ethical/philosophical/religious consequences.

Wojciech May 4, 2012 at 14:57

“Eniac talks about the ideology of ‘life’, not individuals.”
And we are talking about individuals, not panspermia. Not to mention that as we develop our civilization becomes more individualistic, like said before, at the time where technology would exist allowing for intergalactic colonization, we might be a civilization of individuals-each being a nation in itself, rather than the old fashioned nation states.

“Their is never a lack of need to go out and explore the world. I cannot imagine how you envision this. ”
I always stated that advanced civs would likely explore the world-but exploration and research are not equal to colonization.

“Eventually, even the most sophisticated nanosupercomputers will run out of resources to keep this up, and finding places with fresh resources will become number one priority…”
Not really, computational power is easily micro-scaled and there is a limit on extent of your processing facility as you near light speed delays between communication(IIRC something like giant planet computers are possible but not more, as they become inefficient).

Wojciech May 4, 2012 at 14:59

“Modern humans covered the Earth in a few ten thousands of years, starting out from Africa. ”
First Petri dish, now Earth. Both are comparisons to Galaxy, but both are flawed. Galaxy is an immensely hostile place to which our life is not adopted nor was evolved to survive. Both Petri dish and Earth are in general friendly to life-but even your comparison is lacking as places like Antarctica were not colonized by humans in any significant way.

Eniac May 4, 2012 at 19:22

exploration and research are not equal to colonization.

De facto, they are. If you want to explore the galaxy without going yourself, the best approach (and probably the only one that is practical) is to send probes which are able to settle on other stars, develop an industrial infrastructure based on in-situ resources, and then proceed to launch other probes further on. Whether the original biological “founding members” participate in this expansion becomes merely a technicality at this point, with no real consequence.

For such probes, the galaxy is anything but hostile, it is the perfect Petri dish.

Wojciech May 4, 2012 at 22:33

“De facto, they are”
As Antarctic shows-they are not. In Pacific and Asia region, newly discovered shelters for exotic plant and animal species have been kept secret from public to avoid their destruction.
“For such probes, the galaxy is anything but hostile, it is the perfect Petri dish.”
For such probes though such colonization comparable to our Earth examples is no longer needed. And I will believe in von Neumann probe when I see one being built and working ;)

Eniac May 5, 2012 at 22:26

Wojciech:

You have quite a few viewpoints that are hard to reconcile with each other. You think humans will soon transcend to something completely incomprehensible, but you doubt they will be able to build von Neumann machines. You think the future will be dominated by individualism, but you think that somehow all the individuals will be content to stay together in one place, by choice. You say everything will be different in the future, but then you cite examples from the past that “prove” you are right.

Perhaps I misunderstand you, but in any case this all makes little sense to me.

Ole Burde May 6, 2012 at 16:35

@ Ronald
I meant ALL life . Perhabs 100% sure proof of non-detection will be impossible , but to me it seems likely , that a beyond- reasonable-doubt elimination process will soon be possible . This eleimination process gathers momentum from 3 diferent directions :
1. The SETI procect keeps improoving its search algoritms its instrumentatioin and expands into exotic comunication media such as neutrinos.
2. Inside 30 years telescopes will bring spectroscopic evidence of the chemical conditions on the most promising exoplanets .
3.Exoboilogy and comparative ” geology” will create a better undestanding of what to lok for , which is a combination of conditions which could not have happened whithout the ability of life to counterballance or even negate the forces of entropi .

About the filosophical implications : history shows that mankind is capable of keeping focussed on incredible long term projects , if the forces of belief in a sacred mission understandable for the people in gerneral can be incorporated . Such as the pyramids .
To reach the stars in the name of “spreading life into the abyss ” could be such a “mission” or filosophical statement , if engeneered correctly…. remember Harry Seldon from Asimovs Foundation series ?

Ronald May 7, 2012 at 5:44

@Ole Burde: I see what you mean.
However, proof of non-existence of life in our MW galaxy will be extremely difficult if not impossible, because of the obvious immense size and number of stars and planets, and because of the enormous adaptive variations that may exist among microbial lifeforms (think deep underground, deepsea, different metabolisms, etc.).
I agree that we may be able to reasonably proof the (extreme) rarity of (higher, water, carbon and oxygen based) life, if that rarity is the case.
In which case, indeed, we face another interesting opportunity and challenge: to occupy available real estate and seed life (I like that expression).

Ronald May 8, 2012 at 7:23

Slightly off-topic, but did not know where to put this:
In the Proceedings of the National Academy of Sciences there is a fascinating article about what we already suspected, namely that systems with hot Jupiters (giant gas planets in close orbits) most probably do not possess terrestrial planets. ‘Warm Jupiters’ and Hot Neptunes may have them though.
The PNAS article is not free, so I will wait for it to be available on Arxiv.
http://carnegiescience.edu/news/looking_earths_looking_jupiters
http://www.pnas.org/content/early/2012/04/30/1120970109.abstract?sid=77a1ea8b-ceae-452b-835d-20cf02668e7e

ljk May 9, 2012 at 17:25

Alien Life May Not Be So Alien – If It Exists At All

by Jason Major on May 9, 2012

Are we too hopeful in our hunt for extraterrestrial life? Regardless of exoplanet counts, super-Earths and Goldilocks zones, the probability of life elsewhere in the Universe is still a moot point — to date, we still only know of one instance of it. But even if life does exist somehow, somewhere besides Earth, would it really be all that alien?

In a recent paper titled “Bit by Bit: the Darwinian Basis for Life”:

http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001323

Gerald Joyce, Professor of Molecular Biology and Biochemistry at the Scripps Research Institute in La Jolla, CA discusses the nature of “life as we know it” in regards to its fundamental chemical building blocks — DNA, RNA — and how its ability to pass on the memory of its construction separates true biology from mere chemistry.

“Evolution is nothing more than chemistry plus history,” Joyce said during a Public Library of Science podcast.

The amino acids that form DNA here on Earth — the only place in the Universe we know for certain that life can thrive — have proven to be highly successful (obviously). So what’s to say that life elsewhere wouldn’t be based on the same basic building blocks? And if it is, is it really a “new” life form?

Full article here:

http://www.universetoday.com/95071/alien-life-may-not-be-so-alien-if-it-exists-at-all/

Ronald May 16, 2012 at 4:58

Ok, Arxiv has the full article on hot Jupiters and (lack of) terrestrial planets available now:
http://arxiv.org/pdf/1205.2309.pdf

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