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The Universe

  1. Mar 6, 2007 #1
    I have some questions about the universe, am not sure whether they are closer to physics or astronomy..anyway here goes

    1. They say that we are moving away from the sun! but how and where are we getting the energy for that? My speculation is that the sun is creating energy from mass thus its getting lighter, thus its gravitational pull on earth is loosening....
    2. The universe is expanding, according to modern theory..and again is that the energy from the big bang thats still taking effect till now?
    3. Where does the earth gets the energy to rotate around the sun and about itself? is it a kind of regenerative energy, or again its the energy still left since the formation of the earth?
     
  2. jcsd
  3. Mar 6, 2007 #2

    mathman

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    1. Who says???

    2. Partly, but also dark energy is speeding up expansion.

    3. Inertia keeps the earth revolving around the sun and also rotating.
     
  4. Mar 6, 2007 #3
    I've heard it several times on tv shows, only problem is that i don't remember which to confirm. why is it wrong info?

    What is dark energy? sounds as if it's coming out of startrek :P

    ok inertia..so the enrgy from the big bang is still acting on earth..is there any confirmed friction forces that might slow this rotation of the earth?
     
  5. Mar 6, 2007 #4
    1. Whoever said that is plain crazy, unless the earth seems to accelerate from the sun every second, but the acceleration would have to be really slight.

    2. Yup. Thank you Dark Energy; If you wish to know more about this topic, here is a good book to read: Alpha and Omega: http://www.amazon.com/Alpha-Omega-S...1955238?ie=UTF8&s=books&qid=1173217333&sr=8-1

    3. Inertia is a property of matter, and the definition of is resistance to motion. The earth started out as a blob of stuff moving around the sun, and the only friction that could stop the earth is air friction which only would work if the Universe was filled with air, which obviously, is not the case.

    Since Earth has inertia, it would take a large amount of force to stop it due to it's large mass and speed, which is several kilometers per second.

    Btw, did have you taken a Physics class? #3 is actually proven when you use the Law of Inertia, which they teach you in a Physics class.
     
  6. Mar 6, 2007 #5
    well yes i took the course of inertia, and i know what it means, but i was thinking that the atmosphere of the earth could be exerting some kind of frictional effect on the solid surface of earth thus making it lose energy!,a very small amount of energy but we are talking about billions of years here, and not stopping turning in one day or so...
    Besides even if noone said that we are moving away from the sun check this out: The sun is losing mass, thus losing gravitational force, thus we should be moving away from the sun, did u take the equation for gravity?
     
  7. Mar 6, 2007 #6

    russ_watters

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    That would be resistance to acceleration - or in this case, deceleration (which is just acceleration in a negative direction).
     
  8. Mar 6, 2007 #7

    russ_watters

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    There are a number of sources of friction on the earth's rotation. By far the biggest is the tidal friction from the moon and it is noticeably slowing the earth's rotation in the same way tidal friction from the earth slowed the moon's rotation.
    But how much mass does it lose? Over the life of the sun, it isn't enough to make a noticeable difference.
     
  9. Mar 6, 2007 #8
    so if we're moving away from the sun there should be another reason for that! what do u think that reason could be?
     
  10. Mar 6, 2007 #9

    EL

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    First of all, are we moving away from the sun? I have never heard of that.
    And if we are, at what speed? It must be hardly noticable.
     
  11. Mar 6, 2007 #10
    Their was a documentary on Discovery Channel, science..it said that the whole universe is breaking apart-moving away from each other...
     
  12. Mar 6, 2007 #11

    russ_watters

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    That isn't the same thing.
     
  13. Mar 6, 2007 #12
    so where is the difference that i missed?
     
  14. Mar 6, 2007 #13
    oh wait i see. so u mean galaxies are moving away from each other, but inside each galaxy the positions are unchanged ! hmmm
     
  15. Mar 6, 2007 #14
    There is an effect which is making us move very slowly away from the Sun. That is the tidal interaction between the Sun and the Earth. This slows down the rotation of the Sun, and pushes the Earth farther away from the Sun. You can read about tides, as they relate to the Earth-Moon system here. The principle for the Sun-Earth system should be the same. But how big of an effect is this? It turns out that the yearly increase in the distance between the Earth and the Sun from this effect is only about one micrometer (a millionth of a meter, or a ten thousandth of a centimeter). So this is a *very* tiny effect.

    look at what i've found after all...
    http://curious.astro.cornell.edu/question.php?number=317
     
  16. Mar 7, 2007 #15

    EL

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    Yes that's the case!
    The extremely tiny speed at which the earth (apperantly, didn't know that) is moving away from the sun has nothing to do with the cosmic expansion.
     
  17. Mar 11, 2007 #16
    If MadScientist fails to explain something, use Russ!
     
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