Owen, As that last link shows, we really don't know everything there is to know about Population III stars. It was not expected that planets would be found orbiting one, much less one that was 13 billion years old and only 375 light-years away.
As to when did Population-II and I stars form, it was not a straight sequence of III->II->I . Happenstance, as much as anything appears to have dictated when and where the stellar aggregation process resulted in stars of increased metallicity. It is generally true that Pop-I stars are the youngest, but they didn't all form at the same time. I have no idea what the age bracket & error bars for them are. And as to the religion thing: I've learned that you really never do know who you are talking to, and what that other person's biases are, so usually check. I have also learned that there are some striking regional characteristics in this regard. For example, I will never initiate a conversation with someone from the Carolinas on the topic of, say, evolution unless I know the person fairly well. It is downright depressing how many bible-thumping, God fearing, creationist Christian fundamentalists there are in North Carolina or Virginia, two places I travel to fairly often. It makes it extremely difficult to have rational, intelligent, or even moderately pleasant conversations. A group of my coworkers left LANL in 2005 at about the same time I did, but they all went to Blacksburg, VA. It took a major cultural adjustment for some of them to come to grips with the redneck, ignorant, intolerant, bible-literalist culture that is predominant once you get more than 20 miles away from Virginia Tech in any direction. Finally, as you know, I am not a physicist, or cosmologist of any kind. My degrees are in engineering & computer science. I've been informally studying cosmology for as long as I can remember, but I am not a cosmologist. Regardless, I have had the privilege of having had numerous email conversations with Steven Weinberg, who won the Nobel prize in physics in 1979, in which as questioned him on certain issues in his book on cosmology, *The First Two Minutes*. It's a bit dated now, but still worth a read if you haven't done so. I also had the great pleasure of discussing cosmology with Geroge Smoot, for a few hours a couple of years ago. George won the Nobel prize in physics in 2006 for his work on the COBE project. George was one of the keynote speakers at the SuperComputing Conference three of four years ago, and he made himself available after his talk for anyone who wanted to chat. Out of the ~10,000 people attending the conference that year, only 4 of us took advantage of the opportunity. --Doug On Mon, Apr 2, 2012 at 5:01 PM, Owen Densmore <[email protected]> wrote: > Thank you .. very clear. > > Here's the question I haven't been able to find an answer to, and maybe > you have a pointer: when did the Population I stars begin formation and > what has been their relative population since that time? > > If we think Pop III and II stars ended up in supernovas relatively early > .. say at the 4BY point, then I'd agree that we'd have most of the 14BY > since the big bang at our disposal for life formation. > > But if that isn't the case, and Pop I stars didn't appear in interesting > numbers until much later, 8BY say, then my initial surprise holds. > > I do want to be clear this is not a religious thing, that I do accept the > big bang and evolution and that I am not some sort of fundamentalist. (I > only say this because you've asked if I believe in both the big bang and > evolution and I found that odd.) I *certainly* do not have reason to > believe we are the first to the party as you mention below! > > I'm just interested in putting a bit more structure on my initially naive > picture of when life may have started, thus my interest in the metal-rich > stars, and their relative population over the roughly 14BY of the big bang. > > -- Owen > > On Mon, Apr 2, 2012 at 12:08 PM, Douglas Roberts <[email protected]>wrote: > >> Ok, after a night's sleep I can think about addressing your comments, >> Owen. >> >> We appear to differ on the relevance of the scale of time since the big >> bang (presuming you believe in the big bang). The point I was trying to >> make was that human evolution occurred during a cosmological eye-blink of >> time, and "civilization" has lasted for even less than that. >> >> During the period since the big bang, cosmology indicates that >> opportunities for water-life sustaining environments elsewhere in the >> universe have existed for billions of years prior to the present. Even on >> earth, there has been a ~500 million year window that is proven to have >> been capable of sustaining life, with no proof that Homo Sap. is the first >> intelligent life to have evolved here. So I therefore immediately reject >> your seeming assumption that "all life in the universe started at the same >> time" as not having sufficient basis. >> >> Also, considering that red dwarf stars are very long-lived, it is >> possible that life could have evolved on a water-life-friendly planet >> circling one of those billions of years before even single-celled life had >> emerged on Earth. >> >> One additional note related to this from the following article: h >> ttp://www.dailymail.co.uk/sciencetech/article-2123974/IBM-building-powerful-history--hopes-unravel-origin-universe.html >> >> >> *"The SKA’s 15m-dishes, which will detect electromagnetic radiation >> emitted by objects in space, will be the most sensitive ever built - able >> to detect an airport radar on a planet 50 light years away."* >> >> Pretty impressive, yet when you consider that the radius of the >> observable universe is on the order of 45.7 billion light years it becomes >> obvious that we have no way of detecting any indicators of familiar 21st >> century earth-like technology usage other than in our immediate next-door >> stellar neighborhood. >> >> Summarizing, it is the issue of scale, both spatial and temporal that >> leads me to believe that your opinion of us perhaps being the first to the >> party is not defensible. >> >> As to stellar evolution, note that I only mentioned red dwarf stars >> above. But taking other main sequence starts into account only increases >> the potential for life. Even if you wish to preclude all but Sol-class >> main sequence stars, they have a life span of 10 billion years, which >> allows for plenty of evolution opportunities that could have occurred >> before we swaggered onto the scene. >> >> As to what period of time since the big bang would I be comfortable >> trimming down for consideration of when life could have evolved, anywhere: >> I have absolutely no idea. I suspect very few people do. >> >> --Doug >> >> >> On Sun, Apr 1, 2012 at 9:25 PM, Owen Densmore <[email protected]>wrote: >> >>> Doug: I'm not sure if we're on the same page. Let me be as simple as >>> possible. >>> >>> Because I had earlier belonged to the Sagan school of Billions being >>> Important, I had assumed the possibility of life was pretty much spread >>> over the era of galaxy formation. >>> >>> But after being a bit more analytic, it occurred to me that one could >>> reduce one of the billions .. the percent of the life of the universe w/in >>> life formation might occur .. by a considerable amount. >>> >>> What I found interesting was that (considering star generations of >>> import) that all life may be starting at about the same time .. w/in a >>> billion or two years of each other. >>> >>> Does that make sense? You keep blinding me with science and billions, >>> about which I am already aware. I'm interested in a different phenomenon >>> .. adding stellar evolution (and why would you presume I don't understand >>> evolution, of all things) and using that to be a bit more intelligent about >>> boundary conditions. >>> >>> I think the answer is: You don't care about trimming the era of life >>> formation from 12BY say, to 2-4BY. Right? >>> >>> -- Owen >>> >>> On Sun, Apr 1, 2012 at 7:16 PM, Douglas Roberts <[email protected]>wrote: >>> >>>> As to being the first, we've only been civilized, if you can call it >>>> that, for a mere 5,000 years - the working definition for that descriptive >>>> being the length of recorded history. Cripes, we've only existed as a >>>> unique species for ~20,000 year. At the rate we're going, I'd place even >>>> money on us no lasting another 20,000. >>>> >>>> So, given this, and the fact that there has been evolved multicellular, >>>> animate life on the planet for the last ~500 million years, who can state >>>> with authority that we are the first "intelligent" specie to evolve? >>>> >>>> Unless you don't believe in evolution... Oh wait, I guess we decided >>>> not to go there. Back to our main program. >>>> >>>> Anyhow, 500 million years on a geological time scale >>>> is sufficient for subduction to have completely >>>> obliterated sizable portions of earthly real estate. Evidence of some >>>> unfortunate prior specie's ephemeral 20,000 year claim to having become >>>> civilized could well never be found by today's archaeologists. >>>> >>>> This is not a new concept, several science fiction writers have written >>>> stories that transpire over geological time periods. Frederich Pohl, Larry >>>> Niven, and more recently, Michael Seimsen who wrote *The Dig* which >>>> addresses this very proposition. In his story, a hominid species rose to >>>> approximately iron-age levels of technology ~120 million years ago, before >>>> having been being wiped out in the Cretaceous era mass extinction. These >>>> unfortunate individuals had a rough go of it, what with all the dinosaur >>>> predators roaming around at the time (Sarah Palin would have *loved* this >>>> story, presuming she could have gotten past the 6,000 year issue). As a >>>> result of the relative hard times they were living in, these hominids did >>>> not expand to the point of becoming a global blight, unlike the current >>>> inhabitants. The did have art, though. >>>> >>>> On a much broader scale, we have what: 200 billion galaxies that we can >>>> see, each with tens to hundreds of billions of >>>> potentially habitable planets? I have a sneaky suspicion we are not the >>>> first to have experienced "the quickening", universally speaking. >>>> >>>> --Doug >>>> >>>> On Sun, Apr 1, 2012 at 12:42 PM, Owen Densmore <[email protected]>wrote: >>>> >>>>> Gentle readers, as much as I like /.-like digressions, interesting >>>>> humor (but not religious rants), has anyone anything to add to the idea >>>>> that life origins may be bound to the era after Population II star >>>>> formation? >>>>> >>>>> If so, we may be among the first of these very young life forms, +/- a >>>>> billion years or so. >>>>> >>>>> -- Owen >>>>> >>>>> ============================================================ >>>>> FRIAM Applied Complexity Group listserv >>>>> Meets Fridays 9a-11:30 at cafe at St. John's College >>>>> lectures, archives, unsubscribe, maps at http://www.friam.org >>>>> >>>> >>>> >>>> >>>> -- >>>> Doug Roberts >>>> [email protected] >>>> [email protected] >>>> http://parrot-farm.net/Second-Cousins >>>> <http://parrot-farm.net/Second-Cousins> >>>> 505-455-7333 - Office >>>> 505-670-8195 - Cell >>>> >>>> >>>> ============================================================ >>>> FRIAM Applied Complexity Group listserv >>>> Meets Fridays 9a-11:30 at cafe at St. John's College >>>> lectures, archives, unsubscribe, maps at http://www.friam.org >>>> >>> >>> >>> ============================================================ >>> FRIAM Applied Complexity Group listserv >>> Meets Fridays 9a-11:30 at cafe at St. John's College >>> lectures, archives, unsubscribe, maps at http://www.friam.org >>> >> >> >> >> -- >> Doug Roberts >> [email protected] >> [email protected] >> http://parrot-farm.net/Second-Cousins >> <http://parrot-farm.net/Second-Cousins> >> 505-455-7333 - Office >> 505-670-8195 - Cell >> >> >> ============================================================ >> FRIAM Applied Complexity Group listserv >> Meets Fridays 9a-11:30 at cafe at St. John's College >> lectures, archives, unsubscribe, maps at http://www.friam.org >> > > > ============================================================ > FRIAM Applied Complexity Group listserv > Meets Fridays 9a-11:30 at cafe at St. John's College > lectures, archives, unsubscribe, maps at http://www.friam.org > -- Doug Roberts [email protected] [email protected] http://parrot-farm.net/Second-Cousins <http://parrot-farm.net/Second-Cousins> 505-455-7333 - Office 505-670-8195 - Cell
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