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  1. 21 Jan '16 20:58
    So why is there only life on earth? This question is troublesome for most scientists. Here is but one theory as to why

    Astrobiologists from the Australian National University Research School of Earth Sciences suggest that the reason why we haven't encountered alien life is because all the aliens are extinct, the university reported Thursday. In studying how life might develop on other planets, the scientists realized that early critters likely had a hard time quickly evolving to their heating or cooling planets and did not survive.

    "Early life is fragile, so we believe it rarely evolves quickly enough to survive. Most early planetary environments are unstable. To produce a habitable planet, life forms need to regulate greenhouse gases such as water and carbon dioxide to keep surface temperatures stable," Dr. Aditya Chopra said in the paper publishing the astrobiologists' findings.

    "Life on Earth probably played a leading role in stabilizing the planet's climate," co-author Associate Professor Charley Lineweaver said.

    The paradox of astrobiology is that many planets likely check all the boxes for being habitable for life, but we have yet to discover any. The researchers have named their solution to this paradox the "Gaian Bottleneck." "One intriguing prediction of the Gaian Bottleneck model is that the vast majority of fossils in the universe will be from extinct microbial life, not from multicellular species such as dinosaurs or humanoids that take billions of years to evolve," Lineweaver said. —
  2. 21 Jan '16 21:00
    For the theist, why do you suppose that there is only life on earth?

    Obviously, there is no implication that there are other life forms spoken of in the Bible, unless one were to assume that the spiritual world is another life form.
  3. 21 Jan '16 21:07
    Originally posted by whodey
    For the theist, why do you suppose that there is only life on earth?

    Obviously, there is no implication that there are other life forms spoken of in the Bible, unless one were to assume that the spiritual world is another life form.
    I'll leave it to the theists, and the scientist atheist to figure out. As far as I can see they are both grasping at straws and speculating.
  4. 21 Jan '16 21:13
    In 1968, Professor Harold Morowitz, a physicist at Yale University, published the book "Energy Flow in Biology". Along with other physicists and mathmaticians, he had become concerned about the casualness with which some scientists studying the origins of life were assuming that unlikely events must have occurred. These scientists were making assumptions without any attempt to rigorously investigate the probability of such events. Morowitz presented computations of the time required for random chemical reactions to form a bacterium -- not an organism as complex as a human, not even a flower, just a simple, single celled bacterium. Basing his calculations on optimistically rapid rates of reactions, the calculated time for the bacterium to form exceeds not only the 4.5 billion year age of the Earth, but also the entire 15 billion year age of the universe. The likelihood of random processes producing life from a primordial bath of chemicals is even less likely than that of your shaking an omelet and having the yolk and the white separate back into the original form of the eggs.
  5. 21 Jan '16 21:19 / 1 edit
    The oldest sedimentary rocks are dated at about 3.8 billion years on earth. The oldest evidence of fossil forms found in rocks is about 3.3 billion years. So in this span of about 500 million years, the common ancestor of life must have developed the extraordinary and exquisite chemistry of life and also mutated sufficiently to have produced a variety of progeny.

    As a result, it would appear that life appeared on Earth about as soon as it formed. This has led Nobel laureates Svante August Arrhenius and Francis Crick and astronomer Sir Fred Hoyle, and others, who have come to the conclusion that our origins must have originated somewhere other than Earth.
  6. 21 Jan '16 21:20
    Originally posted by whodey
    So why is there only life on earth? This question is troublesome for most scientists.
    No it's not - it's a stupid question because it presumes something we don't know.

    Why have we never encountered alien life? Because, if it exists, it is most likely very far away as space is mostly empty and inhospitable to life. There is only a tiny fraction of space available for us to investigate and look for traces of life.
  7. 21 Jan '16 21:22
    Originally posted by KazetNagorra
    No it's not - it's a stupid question because it presumes something we don't know.

    Why have we never encountered alien life? Because, if it exists, it is most likely very far away as space is mostly empty and inhospitable to life. There is only a tiny fraction of space available for us to investigate and look for traces of life.
    Questioning why we find no life on other planets is a stupid question?

    All righty then.
  8. Standard member RJHinds
    The Near Genius
    21 Jan '16 21:36
    Originally posted by whodey
    Questioning why we find no life on other planets is a stupid question?

    All righty then.
    It is also stupid to look for life on other planets.
  9. 21 Jan '16 21:42
    Originally posted by whodey
    Questioning why we find no life on other planets is a stupid question?

    All righty then.
    No, that's not the stupid question because that's not question you asked.
  10. Standard member wolfgang59
    Infidel
    21 Jan '16 21:58
    Originally posted by whodey
    Basing his calculations on optimistically rapid rates of reactions, the calculated time for the bacterium to form exceeds not only the 4.5 billion year age of the Earth, but also the entire 15 billion year age of the universe. .
    The conclusion then is that life did not form.


    ... or maybe we do not know enough yet?
  11. Standard member sonhouse
    Fast and Curious
    21 Jan '16 23:13
    Originally posted by wolfgang59
    The conclusion then is that life did not form.


    ... or maybe we do not know enough yet?
    I think it safe to say life appeared somehow on Earth. It is probably safe to say if we ever find the means to go to other stars we will eventually find life there too. Maybe only microbes but that remains to be seen.

    Like the Katz said, space is big and mostly empty but just because we have not found evidence for life doesn't mean there is no life, only that we have not found it yet.

    We may find life on Mars, and there are hints of some anomalies in the atmosphere on Venus where presumably it is WAY to hostile for life on the surface by maybe there are microbes of some kind in the atmosphere way above the killing heat and killing atmosphere. Venus is as good a description of hell as we could ask for with the possible exception of the surface of the sun. Atmosphere pressure around that of a full nitrogen bottle, 1500 PSI or so and temperature of around 400 C, not a place to visit.

    But above all that there are hints of something going on we may be able to probe someday, collect samples in some kind of fly by and return to Earth.

    That would be a kick to find life in the upper atmosphere of Venus.

    But we might find it in the future on Mars or even in those underground oceans alleged to exist on some of the moons of Jupiter and Saturn. That will be in the next century or beyond.

    We are in no special place in our galaxy and no special place in our universe except our sun happens to be one with 'metals', a lot of stars are low metal stars and any planets around them would also be low in metals needed for trace elements needed for life, at least our style of life.

    That said, there are literally billions of suns just like our sun, lots of metallic's to spread around.

    It looks certain for long term implications for life elsewhere there would need to be a nice strong magnetic shield around a planet to protect it from the influx of ions and radiation from it's parent star.

    Without that you get Mars, where it once had a nice thick atmosphere and liquid water oceans, all that was lost when its magnetic field dried up and all that is left now are bits and pieces of magnetic lines scattered around the planet so the atmosphere and water were stripped away leaving the mess we see now. That does not mean life if it was there, went totally extinct, it might have just gone underground where there is less radiation.
    Of course we won't know till we get there and start digging around.

    But the fact our sun is a pretty common type in our galaxy and every other galaxy in the universe assures there will be SOME with lucky planets in the right place, goldilocks zone and all that, and a nice fat magnetic shield like Earth or Jupiter.

    We may never know that but you never know what is going to happen in science in the next 400 years or so.

    We may not even have to visit personally, but send nanotech probes by the millions that does the job of a super telescope and so forth, a lot of sci fi stories have been written on that theme.

    Of course I know that is just science fiction for now anyway, but a few hundred years from now? Another story perhaps.

    Billions of stars per galaxy, billions of galaxies. Seems a fundamental error to diss the idea of life elsewhere in either our galaxy or the universe.
  12. Subscriber Suzianne
    Misfit Queen
    22 Jan '16 09:38
    Originally posted by sonhouse
    We may not even have to visit personally, but send nanotech probes by the millions that does the job of a super telescope and so forth, a lot of sci fi stories have been written on that theme.
    In this vein, even if we are able to build probes that can accelerate to a significant portion of lightspeed (in order to reach these far-off planets within their design-lifetimes), then the relativistic problem arises that, as time slows down for these probes, their lifetimes increase so that we could never receive any feedback from them about these far-off planets, within our lifetimes.
  13. 22 Jan '16 09:47
    Originally posted by whodey
    Questioning why we find no life on other planets is a stupid question?

    All righty then.
    It is a stupid question because we haven't found no life on other planets. We have not yet found life on other planets which is not the same thing at all. The main reason we have not found life on other planets is we haven't looked.

    So far we have had a cursory glance at the surface of Mars and the Moon. We have not checked any other planet in our solar system well enough to even rule out life on the surface. We have checked no planets other than the earth below the surface.

    Given that we have so far given a cursory glance at one planet out of a over a thousand billion billion that exist in the visible universe it is a stupid question to ask why we find no life on other planets.
  14. 22 Jan '16 09:53
    Originally posted by whodey
    The likelihood of random processes....
    Processes are not random by definition. The word 'process' means 'obeys a rule' ie another way of saying 'non random'.
    Now one could read your sentence as referring to randomly selected processes, but I am certain that that is not what the calculation actually did. If you are reporting correctly what Professor Harold Morowitz actually did then he doesn't deserve his professorship.
  15. 22 Jan '16 09:57
    Originally posted by Suzianne
    In this vein, even if we are able to build probes that can accelerate to a significant portion of lightspeed (in order to reach these far-off planets within their design-lifetimes), then the relativistic problem arises that, as time slows down for these probes, their lifetimes increase so that we could never receive any feedback from them about these far-off planets, within our lifetimes.
    It has nothing whatsoever to do with relativistic time changes. There is only one issue, the speed of light ie how long it takes for the probes to get there from our perspective and how long a signal takes to get back.