Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Life in the early universe

  1. Aug 31, 2011 #1
    Hello Folks,

    I have an interesting question (I think)... how far back in the history of universe would you have to go before any form of life existed?

  2. jcsd
  3. Aug 31, 2011 #2
    ... sorry, answered my own question. It was 12.7 billion years ago. After the first supernova's seeded space with the elements required for life.

    Interestingly, the oldest object we've seen is 13 billion years old... something older than the possibility for life itself... wonder what implications that has for quantum enthusiasts that wonder if there is truly a physical universe in the absence of a biological observer. I guess there must have been.
  4. Aug 31, 2011 #3
    I guess the physical universe Now could be more so described as a translation of the biological observer, from how it subjectively perceives the effects on it's senses microscopically as contrasted with how the senses are objectively manifested macroscopically. Technically the energy of the 10^-44 universe is still conserved and conversed in how we perceive our reality.
  5. Aug 31, 2011 #4
    If you presume, with no evidence or theoretical foundation, that supernova explosions are prerequisites for life. Which by the way also requires a definition of life, and there is no consensus on what that definition is - and even if we had one we could all agree on, it would necessarily only encompass all life as we know it. So you see the problems inherent in your question.
  6. Sep 1, 2011 #5


    User Avatar
    Science Advisor
    Gold Member

    The first supernova/hypernova probably did not originate until the universe was about 500 million years old. Given life as we can imagine it demands an abundance of metallicity, it appears unlikely it could have originated less than ~ 5 billion years after the big bang - or between 8 - 9 billion years ago.
  7. Sep 1, 2011 #6


    User Avatar
    Gold Member
    2016 Award

    When you say you answered your own question, I disagree completely. Your question was about "EXISTANCE" not "might have existed" and as Chronos properly pointed out, "EXISTS" is likely to be WAY different that "might have"
  8. Sep 1, 2011 #7
    How do I create a thread here
  9. Sep 1, 2011 #8


    User Avatar

    Staff: Mentor

    Simply go to the relevant forum and you should see in the top left (above the list) a button marked "new topic". Welcome to PF :smile:
    This is largely an unanswerable question as we do not know what conditions are necessary to give rise to life. We have some idea about life on Earth but this is all. Therefore the only meaningful question is "how early could Earth-like life have come into existence?" to which I would suggest the answer would be closely linked to "when did the first Earth-like planets form?"
  10. Sep 1, 2011 #9
  11. Sep 2, 2011 #10

    According to my basic equation, the amount of universal evolutionary time required to generate self-replicating RNA:
    [tex]t_{RNA} = dt_1 + dt_2 + dt_3 + dt_4 = (t_u - t_s) + (t_{\odot} - t_E) + (t_E - t_z) + (t_z - t_l)[/tex]
    [tex]\boxed{t_{RNA} = 1.22 \cdot 10^{9} \; \text{y}}[/tex]
    The first self-replicating RNA life could have been generated 1.22 billion years after the Big Bang on the inner planets around second generation and third generation stars, which formed together at the same time.

    dt_1 - minimum time required for second generation stars to form.
    dt_2 - minimum time required for inner planets to form.
    dt_3 - minimum time required for liquid water to form.
    dt_4 - minimum time required for RNA life to form.

    [tex]t_u = 13.85 \cdot 10^{9} \; \text{y}[/tex]
    [tex]t_s = 13.2 \cdot 10^{9} \; \text{y}[/tex]
    [tex]t_{\odot} = 4.57 \cdot 10^{9} \; \text{y}[/tex]
    [tex]t_E = 4.54 \cdot 10^{9} \; \text{y}[/tex]
    [tex]t_z = 4.4 \cdot 10^{9} \; \text{y}[/tex]
    [tex]t_l = 4.0 \cdot 10^{9} \; \text{y}[/tex]
    t_u - Universe age
    t_s - oldest second generation star age in Milky Way galaxy
    t_O - solar age
    t_E - Earth age
    t_z - oldest Zircon age
    t_l - oldest fossilized RNA life age

    http://en.wikipedia.org/wiki/Universe" [Broken]
    http://en.wikipedia.org/wiki/HE_1523-0901" [Broken]
    http://en.wikipedia.org/wiki/Sun" [Broken]
    http://en.wikipedia.org/wiki/Earth" [Broken]
    http://en.wikipedia.org/wiki/Cryptic_era" [Broken]
    http://en.wikipedia.org/wiki/Basin_Groups" [Broken]

    Attached Files:

    • 001.JPG
      File size:
      29.9 KB
    Last edited by a moderator: May 5, 2017
  12. Sep 2, 2011 #11
    Orion1, nice formula. Of course, we only have a sample of 1 with Earth, so your dt_2 and dt_3 can only be taken as rough approximations.

    I think Chronos made a good point about requiring an abundance of metallicity. The first string of second generation stars might not have had sufficient "abundance." Of course, this plays with probabilities. For anything more accurate, one might need to model dispersal of early universe "metals," and the likelihood that those metals would remain in sufficient concentrations upon nebular collapse to yield metal-rich planetary bodies.

    Could some of the so-called first string, second generation stars have modified metallicities from nebula passage doping? That could certainly skew any models. Such a star might look fairly metal-rich, but did it start out that way? If not, then it is quite likely that any planets it possesses would not have snared a comparable load of "metals" from the process (smaller cross section and smaller gravity potential). Such planets, then, would likely only be hydrogen-helium gas giants with a little "flavoring."
  13. Sep 3, 2011 #12
    All the solar inner planets probably formed from a stellar accretion disc at the same time, regardless of their mass and distance from their primary star, some 4.54 billion years ago.

    I have attached a plot based upon the model in post #10 with the stellar generation number on the x-axis and the Iron to Hydrogen (Fe/H) ratio on the y-axis.

    Even though second and third generation stars formed at the same time, the inner planets for second generation stars are probably dwarf planets composed primarily of Period I-III elements (Carbon, Silicon) and inner planets around third generation stars are probably composed primarily of Period III-IV elements (Silicon, Iron).

    http://en.wikipedia.org/wiki/Metallicity" [Broken]

    Attached Files:

    Last edited by a moderator: May 5, 2017
  14. Sep 6, 2011 #13
    Early Life

    The chemical necessities seem to exist at a very early stage. In fact, I am fond of saying the universe is old enough that anything that could happen has already happened. I base this on the fact our own sun is, I believe, third generation and thus our solar system includes all the elements of the Periodic Table.

    However, we have absolutely no evidence life exists anyplace else in the Universe. In fact, over the last half century all, or almost all, of the accumulated data on the subject has REDUCED the statistical probability of other civilizations by many orders of magnitude. My friends simply tell me the mathematics are not in my favor: Billions of solar systems in billions of galaxies.

    I have been keeping a log book on The Drake Equation. The original Wild *** Guess, I believe, was nineteen technologically advance civilizations within our own Galaxy. During the last several decades, however, actual data accumulation has reduced this SWAG by many orders of magnitude.

    Here are a few of the data sets:

    1) Not only is there a Goldie Locks zone in our solar system, there is a Goldie Locks zone in our own Galaxy. The last time I heard an estimate was that many millions of suns are in our Galactic Goldie Locks Zone. So forget about billions and billions of potentially habitable planets in the Milky Way. But I am happy with millions.

    2) But it gets worse. It always gets worse. We have actually sampled several hundred planetary systems. and not one single one of them seems even remotely conducive to complex life. For instance, the norm seems to be that Gas Giants normally occupy orbits within their respective inner solar systems.

    3) However, the most discouraging SETI statistic has to be the fact that our own gloriously human friendly cosmological situation is a statistical rounding error of about .000,001. In five billion years, we have managed to accumulate one single mathematically capable species descended from nothing more then a few hundred breading pairs.

    I really really want to talk with ET. So lets keep listening. But lest not hold our breath.
  15. Sep 7, 2011 #14


    User Avatar

    Staff: Mentor

    This is of course only (potentially) true for the specific kind of biochemistry of life we are familiar with and not a statement about life in general.
    I'd be aware of the statistics of this observation. Firstly hundreds of systems is not significant and secondly we are using limited instruments that have a far easier time picking out large mass objects.

    In addendum my first point still stands; for all you know everyone of those gas giants is teeming with life.
    We evolved to the level we are now over the past few million years. There is little reason why throughout most of post-Cambrian history a species could not evolve with our level of intelligence. The reason is that selective pressure happened to show itself when it did and evolution managed to follow this path. It is nonsensical to say "this even happened once in X therefore the chance is 1 in X" because you have no idea of the variables involved.
  16. Sep 7, 2011 #15
    Yes we do place a lot of empahsis on our single sample of life. It may actually be that life on rocky planets is a rarity and gaseous planets are abundant - until we have a decent sample, once we have warp drive, then we will know :smile:
  17. Sep 17, 2011 #16


    User Avatar
    Gold Member

    and thirdly, we are only looking in a small temporal window; if life is pervasive in the universe, many systems would have bypassed (or have yet to pass through) a habitable stage. Whole arrays of species could have evolved and went extinct long ago, or won't evolve until long after humans are extinct and the Earth is cold.

    We may very well always be alone locally, even if we're not alone in the whole spatiotemporal frame of the universe.
  18. Sep 26, 2011 #17
    According to the work of Carl Gibson, and colleagues, the first Biocompatible planets appeared about 3 million years after the Big Bang...

  19. Jan 24, 2012 #18
    Taking the goldy zone theory into theory, do you believe that there is more intelligent life out there sometime in the past or present. Or do you guys believe that all this space is needed for us to survive?
  20. Jan 24, 2012 #19


    User Avatar

    Staff: Mentor

    Patently we don't need all this space to survive insofar as the universe was necessary for Earth and thus us to come about.

    As to whether or not there has been or is tool-using, sentient life in the universe I have no idea. Whilst stars with planets seem to be common in the galaxy we have no way of knowing how likely or common it is for life to form and no idea how common it is for sentient, tool-using life to evolve on these planets, until we get meaningful data for that and plug it into the Drake equation (or something similar) we can't really talk about probability. An if we assume for a moment that tool-using, sentient life has evolved at some point in the galaxy's/universe's past the Fermi paradox rears it's ugly head.
  21. Oct 18, 2012 #20
    I have a request for a more mathematically able PFer, and it relates to the SETI question.

    I'd like to have a way (i.e. mathematical method) of thinking about how likely it is for any technical-species bearing planet to encounter radio transmissions sent by another technical species.

    Lets say that once a species develops that is capable of producing technological societies it takes 100,000 years to reach the level of sending / receiving radio waves. Also lets say there is a time window of 1000 years where radio technology is frequently utilized, call it the receiving/broadcasting window.

    My intuition is that I would model this using a differential equation that describes an expanding sphere of radio waves 1000ly thick, then find out the probability that this sphere intersects another technical planet during that planets radio-window. However, I'm afraid I haven't yet acquired the right calculus methods to describe that, and also I'm not sure how the statistical mechanics plays in here determining the probability of interception based on likelihood/distribution of technical civilizations.

    What makes me bring this up is the question on whether there are intelligent species past our present. I suppose this is how we would go about estimating the likelihood of hearing from them.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Life in the early universe
  1. The early universe (Replies: 22)

  2. The early universe (Replies: 1)

  3. Life in the universe. (Replies: 91)