Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 30

Thread: why life exist only on earth?

  1. #11
    Senior Member
    Join Date
    Jul 2006
    Location
    Placerville, CA
    Posts
    8,259
    Quote Originally Posted by Buck_Nastier
    Adi, it depends on what you consider "life".

    If scientists found living organisms deep down below the surface of
    Mars, then that would be considered life on another planet.

    The possibility of finding something like that on another planet is
    very good. The possibility of finding life as advanced as we are on
    another planet is not likely.
    The possibility of there being life as or more advanced than we on another planet is likely. "Absence of proof isn't proof of absence.".
    "The world will not perish for want of wonders but for want of wonder."
    J.B.S.Haldane

  2. #12
    We know that prokaryotic life can survive in space. A camera retrieved from an earlier moon mission by Apollo 12 contained Strptococcus that had survived on the moon for three years:
    http://www.guardian.co.uk/life/thisw...532305,00.html
    But scientists have already discovered Earthlings on another heavenly body. A camera in a Surveyor probe sent to the moon was retrieved by the crew of Apollo 12 almost three years later and shipped back to earth again. Within the camera were a colony of Streptococcus mitis, a tiny microbe that had inadvertently stowed away. The Streptococcus survived three years in a vacuum, experiencing extremes of heat and cold, without food or water, bombarded by lethal radiation. When it got back to the home planet it revived, and began to multiply.
    If bacteria can surive the conditions in space then there is a possibility that they have travelled on comets, seeding life from one planet to another - either from Earth to other planets or other plkanet to Earth. This theory is calle panspermia and whilst we do not have evidence that convinces me that it has occurred we do have evidence that bacteria could survive the journey. Not only do we have the Strptococcus from the moon but the only surviviors of the challenger space shuttle crash were bacteria.
    The fact that Earth bacteria can survive and flourish in extreme conditions on Earth, in volcanic vents and nuclear power plants for example, suggests that conditions do not have to be as "life friendly" as they are in large parts of the Earth for life to exist elsewhere in space. Given the huge range of conditions that life can survive in, I would be extremely surprised if suitable conditions for life did not exist in many places elsewhere in the universe and just as surprised if life does not exist in at least a small proportion of these places.

  3. #13
    Quote Originally Posted by Adrian
    We know that prokaryotic life can survive in space. A camera retrieved from an earlier moon mission by Apollo 12 contained Strptococcus that had survived on the moon for three years:
    http://www.guardian.co.uk/life/thisw...532305,00.html


    If bacteria can surive the conditions in space then there is a possibility that they have travelled on comets, seeding life from one planet to another - either from Earth to other planets or other plkanet to Earth. This theory is calle panspermia and whilst we do not have evidence that convinces me that it has occurred we do have evidence that bacteria could survive the journey. Not only do we have the Strptococcus from the moon but the only surviviors of the challenger space shuttle crash were bacteria.
    The fact that Earth bacteria can survive and flourish in extreme conditions on Earth, in volcanic vents and nuclear power plants for example, suggests that conditions do not have to be as "life friendly" as they are in large parts of the Earth for life to exist elsewhere in space. Given the huge range of conditions that life can survive in, I would be extremely surprised if suitable conditions for life did not exist in many places elsewhere in the universe and just as surprised if life does not exist in at least a small proportion of these places.
    I like KLD's statement. It is a conceit of humans to think that we are the only form of "life" worth considering.

    As I have pointed out in another topic regarding the sizes of planets, gravitational force is likely to have a great influence on the manifestions of "organisms". In a small gravitational field planet, like Earth or Mars, life can be our size or bigger. However, in large planets with substantial gravitational fields, organisms may be very different. However, small organisms can form networks that communicate with each other and may be considered a distributed organism.

    The concept of a distributed organism is fascinating. For example, scientists think that some forests are huge organisms composed of many hundreds or thousands of trees that come from a single individual and are connected to each other through a massive root system. Likewise, fungi (mushrooms) are interconnected and can be considered a single organism, as suggested by Thomas Volk in a 2002 article entitled "The Humongus Fungus" (Source), describing a single colony of Armillaria or Honey Mushroom. Genetic analyses revealed that genetically identical members of one single colony may occupy 16 hectare area and is at least 1500 years old, making this among the largest and oldest "organisms" on earth.

    Gravitional fields may also influence the time-scale of organisms. We are used to seeing life that moves and reacts within seconds or minutes. But, it is entirely conceivable that organisms on other planets react to stimuli over a time scale of months, years, or even centuries. We may not be able to perceive life that has a very short or very long time scale. It is also entirely possible that life on other plants evolved using a different genetic and non-carbon-based components. We may simply not be able to recognize life on other planets.

    Wise.
    Last edited by Wise Young; 12-23-2006 at 09:02 AM.

  4. #14
    Senior Member JimD's Avatar
    Join Date
    Dec 2001
    Location
    Long Island, NY
    Posts
    2,092

    Pertinent quote:

    "Sometimes I think we're alone. Sometimes I think we're not. In either case, the thought is staggering."
    - Buckminster Fuller

  5. #15
    Senior Member rdf's Avatar
    Join Date
    Jul 2001
    Location
    Someplace between Nowhere and Goodbye
    Posts
    12,964
    Considering the age of the Universe, and the extreme environments we find life here on Earth, there's no doubt there are and have been lifeforms in other solar systems in our galaxy. And countless other galaxies.

    Hell, whole intelligent civilizations could have flourished for billions of years, and died out, long before the Earth was even created.

    If an intelligent species were to survive long enough without either blowing up its own planet, getting wiped out by an asteroid or comet, or somehow or other coming to an end, then they'd develop the technologly to harness the power of their planet. If they survived longer, they would sooner or later harness the power of a star, and if longer still, they'd be able to harness the power of galaxies.

    With the harnessing of such power, wormholes could be created, defeating the laws of physics which puts a cosmic speed limit at 186,000 miles/second...and allowing for travel from one end of a galaxy to the other in seconds.

    Yeah, I believe there's life out there, intelligent life, and maybe some have survived long enough to create wormholes and travel about the universe. Or they've found other loopholes around the laws of physics. Or maybe we on Earth don't understand physics as much as we think we do. And maybe ETs just haven't seen us yet, or we're not important enough, or we've been explored and are being explored right now.

    Or the ETs could explore using nano-robots who can replicate and study the universe without sending themselves.

    The possiblitiles are endless. As JimD posted, if there is ET life, that'd be amazing. If there isn't ET life, if we're alone in this endless universe, well, that would be equally amazing. So no matter how you look at it, we live in an amazing universe.

    The three types of civilzations I mentioned; able harness power of the planet, harness power of the star, and harnessing the power of the galaxy I believe are how modern-day theoretical physicists type-class civilizations.

    We on Earth today don't rate on that scale as we get out power mainly from dead plants and animals. If we learn to harness the power of our planet's processes, we'll rate at the bottom of the three.
    Last edited by rdf; 12-23-2006 at 06:27 PM.
    Please donate a dollar a day at http://justadollarplease.org.
    Copy and paste this message to the bottom of your signature.

    Thanks!

  6. #16
    Quote Originally Posted by rdf
    Considering the age of the Universe, and the extreme environments we find life here on Earth, there's no doubt there are and have been lifeforms in other solar systems in our galaxy. And countless other galaxies.

    Hell, whole intelligent civilizations could have flourished for billions of years, and died out, long before the Earth was even created.

    If an intelligent species were to survive long enough without either blowing up its own planet, getting wiped out by an asteroid or comet, or somehow or other coming to an end, then they'd develop the technologly to harness the power of their planet. If they survived longer, they would sooner or later harness the power of a star, and if longer still, they'd be able to harness the power of galaxies.

    With the harnessing of such power, wormholes could be created, defeating the laws of physics which puts a cosmic speed limit at 186,000 miles/second...and allowing for travel from one end of a galaxy to the other in seconds.

    Yeah, I believe there's life out there, intelligent life, and maybe some have survived long enough to create wormholes and travel about the universe. Or they've found other loopholes around the laws of physics. Or maybe we on Earth don't understand physics as much as we think we do. And maybe ETs just haven't seen us yet, or we're not important enough, or we've been explored and are being explored right now.

    Or the ETs could explore using nano-robots who can replicate and study the universe without sending themselves.

    The possiblitiles are endless. As JimD posted, if there is ET life, that'd be amazing. If there isn't ET life, if we're alone in this endless universe, well, that would be equally amazing. So no matter how you look at it, we live in an amazing universe.

    The three types of civilzations I mentioned; able harness power of the planet, harness power of the star, and harnessing the power of the galaxy I believe are how modern-day theoretical physicists type-class civilizations.

    We on Earth today don't rate on that scale as we get out power mainly from dead plants and animals. If we learn to harness the power of our planet's processes, we'll rate at the bottom of the three.
    rdf,

    We humans ain't that shabby... .

    We have harnessed the power of the sun and our planet on a scale that we need. Energy trapped in carbon deposits are a form of solar energy, collected over many years without any effort on our part. We do use some of the intrinsic energy of our planet, including volcanic heat, waves, wind, and magnetic energy. In the past century, we have discovered and harnessed nuclear power, including nuclear fusion which is of course the basis of our solar energy.

    Admittedly, we have not yet conquered the lightspeed barrier. However, slower than light-speed travel is not so bad. Time is only relative. Greater-than-lightspeed travel is only necessary for distant galaxies. Within a few years of travel from earth, there is a great deal to explore and learn in the coming century. Also, I am not sure that humans are ready yet to meet other life forms. If we were to meet with any of the life-forms that you postulated, it will be our demise.

    In the meantime, we have a lot yet to accomplish on this earth. We must learn how to live on this planet without destroying it. It would be nice if we learned how to cure spinal cord injury and other incurable conditions. It would be great if we learned how to live with each other without all the murder and mayhem. In all our history, we have yet to achieve "peace on earth and good will to all men." Maybe we can achieve these goals in our lifetime. Merry and Happy to you.

    Wise.

  7. #17
    Senior Member rdf's Avatar
    Join Date
    Jul 2001
    Location
    Someplace between Nowhere and Goodbye
    Posts
    12,964
    Quote Originally Posted by Wise Young
    rdf,

    We humans ain't that shabby... .

    We have harnessed the power of the sun and our planet on a scale that we need. Energy trapped in carbon deposits are a form of solar energy, collected over many years without any effort on our part. We do use some of the intrinsic energy of our planet, including volcanic heat, waves, wind, and magnetic energy. In the past century, we have discovered and harnessed nuclear power, including nuclear fusion which is of course the basis of our solar energy.

    Admittedly, we have not yet conquered the lightspeed barrier. However, slower than light-speed travel is not so bad. Time is only relative. Greater-than-lightspeed travel is only necessary for distant galaxies. Within a few years of travel from earth, there is a great deal to explore and learn in the coming century. Also, I am not sure that humans are ready yet to meet other life forms. If we were to meet with any of the life-forms that you postulated, it will be our demise.

    In the meantime, we have a lot yet to accomplish on this earth. We must learn how to live on this planet without destroying it. It would be nice if we learned how to cure spinal cord injury and other incurable conditions. It would be great if we learned how to live with each other without all the murder and mayhem. In all our history, we have yet to achieve "peace on earth and good will to all men." Maybe we can achieve these goals in our lifetime. Merry and Happy to you.

    Wise.
    You're very right, Wise. I wasn't demeaning humans on Earth or belittling our accomplishments, just theorizing. It's interesting that you mention achieving peace on earth, as this is an absolute prerequisite to not only survival, but any extra-solar explanatory agenda.

    Theorizing, it brings to mind the Drake equation, which I learned in a high-school astronomy and has been tossed around for years:

    ---------
    The Drake Equation, as far as mathematical equations go, is quite simple. It consists of a string of unknowns multiplied by each other - that's it, no integration, no differentiation, nothing more difficult that multiplication. This means that the equation is accessible to pretty much everyone. Here it is: N = R* fp ne f l fi fc L Where:
    • R* is rate of formation of suitable stars (stars like the Sun) in the Milky Way galaxy
    • fp is the fraction of those stars that have planets
    • ne is the number of planets capable of sustaining life around each of those stars having planets
    • fl is the fraction of planets capable of sustaining life that actually evolve life
    • fi is the fraction of those planets where live has evolved that evolve intelligent life
    • fc is the fraction of planets with intelligent life that develop the capability to communicate
    • L is the fraction of the planet's life during which the intelligent life can communicate
    • MORE
    -----

    The only problem with his equation is we don't know most of the values. Hell, we only know one or two. But even using conservative numbers for the values, the outcome is still millions of planets with intelligent life.

    I believe the Europeans have recently launched a new telescope that will be able to detect smaller planets than we can now detect. It should be able to see planets maybe 3 times as big as Earth. Now, we only find Jupiter sized and bigger planets. Instead of finding them by measuring the "wobble," or "doppler shift," caused by gravitation of an orbiting planet on a star, it'll measure the "blink" of light when a planet orbits its star. NASA might be involved with this telescope, too.

    But I know NASA has an even better telescope planned to launch in the next 5 or ten years that'll be able to detect Earth sized planets. Imagine that! In a few years, we'll be discovering planets our size in our galaxy...and if a planet is our size or even twice as big, it can't be made of gas, it'll be rocky.

    And with our ability to decipher all realms of the visible, infrared, x-ray, ultra-violet, radio, etc., light spectrums and each planet's chemical makeup via spectroscopy, we should be able to tell if plant-life exists on these planets by studying the light and radiation they give off. I may be jumping the gun a bit, but I believe this is possible with this new telescope and our ability to decipher the chemicals on the planet via the planet's light and radiation.

    (Imagine if we found a planet giving off high levels of methane and carbon dioxide )

    I'm shooting from the hip here, but that's how I understand how we may be able to see if life exists on these earth-sized or two-times earth-sized planets that we'll certainly discover in the near future.

    I should have gone into Astronomy, instead of Aerospace Engineer work. But I'm tired of doing what I'm doing and looking for a change. I'd love to work in Astronomy, or for SETI. Think I'll check out their website, see if they need any help...but I think they've lost most or much of their funding in the last decade.
    Please donate a dollar a day at http://justadollarplease.org.
    Copy and paste this message to the bottom of your signature.

    Thanks!

  8. #18
    Senior Member rdf's Avatar
    Join Date
    Jul 2001
    Location
    Someplace between Nowhere and Goodbye
    Posts
    12,964

    COROT to scout for rocky planets around other stars

    Here's the space telescope soon to be launched I mentioned above.

    ----

    COROT to scout for rocky planets around other stars


    Rocky planets not much bigger than Earth could be detected by a space telescope called COROT set to launch on 27 December. The mission is expected to provide a better understanding of planets smaller than Saturn, of which only a small number of examples are known so far.


    The vast majority of the more than 200 extrasolar planets found to date have been detected from the ground by watching for the slight gravitational tug they exert on their parent stars, called the radial velocity technique.


    Most of these planets are similar in mass to Jupiter or even heavier, because these 'gas giants' are the easiest to detect. But the new telescope, called COnvection ROtation and planetary Transits (COROT), will be able to detect much smaller planets.


    The satellite will use its 27-centimetre telescope to search for dips of light due to planets passing in front of their parent stars in events called transits. It will monitor different patches of the sky that each span the width of about six Full Moons, staring at each for 150 days at a time. Watch an animation of the COROT mission.


    The mission is capable of detecting tiny drops in light of only 300 parts per million, which is good enough to detect planets as small as two or three times the size of Earth, says COROT team member Marc Ollivier of the Université Paris-Sud in Orsay, France.

    More

    ----------------------

    Here's the NASA Kepler space telescope I also mentioned, to be launched in 2008.

    ---

    Overview of the Kepler Mission

    Kepler
    ... NASA's first mission capable of finding Earth-size and smaller planets around other stars.
    Importance of Planet Detection

    The centuries-old quest for other worlds like our Earth has been rejuvenated by the intense excitement and popular interest surrounding the discovery of giant planets like Jupiter orbiting stars beyond our solar system.

    With the exception of the pulsar planets, all of the extrasolar planets detected so far are gas giants, approximately 150 as of 2005. The challenge now is to find terrestrial planets (habitable planets like Earth), which are 30 to 600 times less massive than Jupiter.

    The Kepler Mission, a NASA Discovery mission, is specifically designed to survey our region of the Milky Way galaxy to detect and characterize hundreds of Earth-size and smaller planets in or near the habitable zone. The habitable zone encompasses the distances from a star where liquid water can exist on a planet's surface.

    More
    Last edited by rdf; 12-23-2006 at 09:19 PM.
    Please donate a dollar a day at http://justadollarplease.org.
    Copy and paste this message to the bottom of your signature.

    Thanks!

  9. #19
    If Einstein's statement that the universe is absolutely infinite is to be a lemma in an argument, then we can conclude that at some point and location in the universe there are disabled individuals having this exact same conversation at the same time.
    No one ever became unsuccessful by helping others out

  10. #20
    rdf, Thank you. The Drake Equation (formulated in 1961) is a simple probability equation. The website http://www.activemind.com/Mysterious..._equation.html allows you to make the calculation based on various assumptions. Even with relatively generous assumptions such as 100 billion stars, 50% of stars have planets, each of those stars have at least one planet able to support life, 20% of those actually evolved life, 20% of those evolved intelligent life, 20% of those communicated, and those communicating civilizations survived 10,000 years, the number of communicating civilizations is smaller than one would think, about 1000. The number could be easily smaller than 1000, due the generosity of some of the assumptions.

    Regarding SETI and detection of life, I am concerned that we are only looking for carbon-based lives. The more we learn about life, the more varied it seems to be. Wikipedia has a section of an article devoted to silicon-based life. It pointed out that while silica has a similar valency to carbon and can form complex crystals, that some bacteria in fact have silicon dioxide based skeletons, and that spines of the sea urchin are made of silicon dioxide, it suggests that another solvent besides water would be necessary to allow life to form. In particular, the chemistry of silicon-oxygen interactions would not allow diverse and stable silicon compounds.

    The requirement that civilizations must survive for a period of time to increase the chances of detection and live confrontation between them is a particularly interesting one. As a Wikipedia article on SETI suggested:
    The third assumption behind SETI is that intelligent life is not inherently self-destructive, but that it finds a sustainable way of living on its planet. The duration of human beings in relation to earth time has been likened to the thickness of a piece of cigarette paper placed on the topmost railing of the Eiffel Tower. Earth-time is the Eiffel tower, human history is the paper. SETI assumes that two pieces of paper, placed on two separate towers, may exist at exactly the same height, that is, that two or more intelligent civilizations may exist simultaneously, and within a relatively short distance from each other that their radio signals may arrive without extensive degradation. However, the periods of time during which life-bearing planets are formed do in fact vary enormously. If a human civilization capable of sending electromagnetic signals continues for hundreds of thousands of years, the paper becomes a little thicker and the likelihood that we will exist simultaneously with another transmitting/receiving civilization is increased. If however, our civilization destroys itself through nuclear war or as a result of the release of greenhouse gases or other erosions of our life support system, and if other civilizations have the same proclivities, then the probability of two competent civilizations coinciding in time and making contact with each other becomes vanishingly small.
    I am not sure that I would like being a scientist working on SETI. While the concept is fascinating, the likelihood that I will encounter extraterrestrial intelligent life in my lifetime is likely to be very low. To spend one's whole life on SETI research without a reasonable probability of finding it would probably be very discouraging. On the other hand, I believe that there is much that we can do in science that will have an impact on our world in our lifetime The 20th Century was really the century of physics where the boundaries of our world both in the subatomic and super-macroscopic sense expanded markedly. It was a century during which all our major theories concerning energy, matter, and the expanding universe became well-substantiated.

    The 21st century is really the time for biology. After dispelling lingering doubts about evolution and how long humans have been on earth, and the development of molecular tools, we have begun to explore the nature and complexity of life on earth for the first time. In the past decade, we have decisively overturned the dogma that the adult central nervous system cannot regenerate or produce new neurons. We are now well on the way to discovering how to manipulate gene expression and stem cells so that this knowledge can be applied to repairing the central nervous system and restoring function. I tell my students that there has been no other time in human history like now, that whatever I teach them today will probably be untrue within a decade when they become practicing doctors, biologists, or neuroscientists.

    Finally, regarding peace on earth, I saw a movie yesterday that stimulated a great deal of thought: "The Curse of the Golden Flower" (Source). On the surface, the movie was an depressing story of an emperor who battled his family for power. However, upon further thought, it is a very interesting exposition of the difference between the Eastern and Western cultures. As with several other movies made by Zhang Yimou (like Hero), it carried a powerful message. That message is the same as the famous Borg phrase from Star Trek (Source): "Resistance is futile." Unlike American movies that usually celebrate the victory of the individual over the system, Chinese movies often celebrate the victory of the system over the individual. "The Curse of the Gold Flower" suggests that sacrifice, bravery, lust, love, filial piety, and everything else that the individual feels and does are not only unimportant but irrelevant if that individual bucks the system. The system will crush the individual. Peace and order take precedence over the individual. Is this an acceptable price for peace?

    Wise.
    Last edited by Wise Young; 12-25-2006 at 08:33 PM.

Similar Threads

  1. Replies: 2
    Last Post: 08-26-2003, 01:18 PM
  2. Life is swell
    By antiquity in forum Recreation, Sports, Travel, & Hobbies
    Replies: 0
    Last Post: 02-04-2003, 01:58 PM
  3. The Life (& Death?) of Cloning
    By Max in forum Cure
    Replies: 0
    Last Post: 05-26-2002, 05:47 PM
  4. Replies: 7
    Last Post: 01-24-2002, 03:13 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •