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Life's contribution to Earth's weight and gravity?

  1. Mar 21, 2009 #1


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    This is a bit of an odd question, but I was wondering. What kind of contribution would life have made to Earth's overall weight? Also, would a decayed body still weigh the same weight if all of the forms of decay were in a controled enviroment? I started pondering this the other day when thinking about life growing up, constantly gaining weight as we grow. I also wondered what kind of implications it might have had on Earth and it's gravitational forces over the years.

    It's kind of a stupid question, but thanks for any input...
  2. jcsd
  3. Mar 21, 2009 #2


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    Staff: Mentor

    All of the mass of a person comes from the earth, so there is no change in mass due to living things.
  4. Mar 21, 2009 #3
    Contrarily, life makes Earth lighter a little bit because of some spacecrafts plunging into the universe. Except from that, the weight of the Earth is stable no mater life does exitst or not.
  5. Mar 21, 2009 #4


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    Science Advisor

    Offset in turn just a tad by scraps from the Moon or comets that we've brought back. (As long as we are considering small effects.) :wink:
  6. Mar 22, 2009 #5
    Well, hold up.

    People - and animals - tend to concentrate in cities. For instance, there are many more people living in New York, NY than in Middleofnowheretonshire, PA. Also, cities weigh more than farms naturally, as there are more buildings, more cars, etc.

    If the distribution of cities isn't symmetric enough, it's entirely possibly that life alters the Earth's gravitational profile in a way which is less random than it would be if non-biological processes were the only motors of change.

    As a proof of concept, say that 1% of the Earth's mass makes up what humans can play around with. Say we move all this to one spot on the Earth's surface. Then we will have slightly shifted the center of mass of the Earth.
  7. Mar 22, 2009 #6


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    Staff: Mentor

    And because of the electromagnetic radiation that we're constantly producing, e.g. those "Leave It to Beaver" TV programs that are now about fifty light-years away from us.

    Now, there's a "Fermi problem" for you! Estimate the mass equivalent that was radiated away during one such half-hour program. :uhh:
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