pywakit Posted February 4, 2010 Share Posted February 4, 2010 Well, if one takes into account GR, any orbiting bodies will radiate gravitational waves and the orbits will decay over time. No need for any external perturbation. At last swansont and I agree on something. Merged post follows: Consecutive posts mergedAssuming no cosmic expansion we would have to assume that at the moment of creation these 2 planets simply came into being. In this case, they would not initially affect one another. The instant they appear, each one would send out gravity waves in all directions at the speed of light, so neither one would move at all for the first 100,000,000 years and would then start moving towards one another. The point about 2 objects a septillion light years apart is a bit shaky as it would take a septillion years for gravity waves from these objects to reach each other. This is almost certainly longer than the lifetime of our universe and so no, these hypothetical objects would not interact. Also, Hi, cool forum! Fascinating that you can give the 'universe' a lifespan. Care to support that assertion? How do you 'measure' the lifespan? What criteria are you using? What is YOUR definition of 'lifespan'? And you are incorrect. Those two objects' gravitational waves were in communication from the start. BEFORE they were a septillion light years apart. They didn't just 'pop' into existence. So no matter how far they may have become seperated, they will ALWAYS remain in communication. Unless you would like to disprove GR. So yes. They DO interact. Merged post follows: Consecutive posts mergedSo the question is why is there motion in the universe? Because the initial conditions of the universe were not in a stabile configuration. Why not? Because it was not completely uniform. Why not? Good question. Presumably because of random quantum effects. Or ... according to recent findings/observations, the universe was much lumpier at the beginning than we have assumed. If there were UMBHs from the very beginning ... or very CLOSE to the beginning, then the gravitational waves from these BHs would have done a great job of perturbing the plasma ... then the gasses, and dust. Link to comment Share on other sites More sharing options...
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