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Is life a given on other planets

  1. Jul 12, 2016 #1


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  2. jcsd
  3. Jul 12, 2016 #2
    Life in any form we recognise can't have existed in the early universe since the only atoms around were Hydrogen and Helium.
    It probably can't exist in the distant future either since if the heat death scenario is true, there isn't sufficient energy density.
    The goldilocks zone in between though could be just a very brief several billlion years, or then it could be trillions.
    The Universe in it's present state contains copious amounts of the elements needed for life, and star forming regions, so therefore planets with the possibility of life are common.
    Life being possible doesn't mean it must happen wherever it can though
  4. Jul 12, 2016 #3


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    The simple answer is that we don't know. As Fermi pointed out, if intelligent life like us were exceedingly common, they would be here by now.
  5. Jul 12, 2016 #4


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    We don't know, but some will speculate. We can certainly identify some conditions necessary for life as we know it, e.g., the present of H, C, N, O, . . . . However, as rootone indicated, the Goldilock's zones seem rather unique.

    That would only apply to the solar system. We are incapable of human interstellar travel at the moment, which is probably a good thing. Assuming the physics is the same elsewhere, even a somewhat more advanced civilization would face the same constraints.
  6. Jul 12, 2016 #5
    How closely have we even looked? Surely our capability to scout for life, let alone intelligent life, in other galaxies is severely limited. I would not be surprised if intelligent life was abundant throughout the universe.
  7. Jul 12, 2016 #6
    But then as phyzguy pointed out there is the Fermi paradox.
    If intelligent life was abundant, that means other intelligent life forms should be clearly visible in radio or other signals, or even being obviously present elsewhere in the solar system.
  8. Jul 13, 2016 #7


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    I think we will never know, if life is present now the huge distances will preclude communication, as i see it only a very advanced civilization would be able to interface
    with us.
  9. Jul 14, 2016 #8
    I would say yes, Life is a given, probably on Mars at some point in the past, probably on Europa and Enceladus now and in the past/future and possibly on other moons or asteroids with water ice (Crete?). Life is also probably spread across the galaxy and galaxy super clusters, ect.. Most life would be simple single and multi cell life. Some complex multi cell life and varying degrees of intelligent life.

    I assume any significantly intelligent life follows similar technological evolution as us on Earth. Tools, shaping metals, complex machines, radio, computers ect. There could also be intelligent alien mammals (dolphin like) or monkey like creatures where the mutation for higher intelligence never get triggered before that species goes extinct. For example Earth without human level intelligence leaving Chimps and sea mammals as the most intelligent life.

    A far more interesting area in my opinion is Alien super AI and organic/synthetic life forms. Assuming there are a few alien civilizations out there that have had time to properly develop their technology and have avoided self inflected or extraterrestrial extinction, they should develop AI at some point. Alien AI could also be the only remaining manifestation of the previous intelligent organic life in that part of the galaxy or it could be the final evolution of it. Or it could be a complex space exploring probe from an advanced organic civilization. Since an advanced super intelligent AI probe would be ideal for long distance space exploration.

    There are so many interesting questions that arise, what would happen if we were able to make contact with said probe or alien civilization.
    Would they be more advanced or just about the same as human civilization trying to figure out their place in the neighborhood too?
    What would we learn from each other? Would any advanced civilization or probes even want to talk to us or even reveal them selves to us? (ex. zoo hypothesis)
    What if we received a signal saying we must cease all raido/tv broadcast so as not to make our selves noticed because there are other hostile life forms in the galaxy..?
    How would the people of earth react to knowing there are other intelligent life forms in the Galaxy, would major religions crumble or adapt? would the human race be more united or divided?

    I often struggle sleeping at night wondering if there is another life form a few tens of light years thinking the same thing right now or maybe there was another life form thinking the same thing 2 billion years ago while the earth was still evolving and we're just late to the party. The great time scales of the universe make almost anything seem possible. Another deeper rabbit hole is the possibility of alternate universes or the multiverse but that is for another thread.
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