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Ruplusive Force or Lost Of Mass

  1. Jul 26, 2008 #1
    Not sure what forum this question belongs in... so I'll post it here.

    I understand the concept of gravity warping space but intuitively it's never sat well. But, hey, no one can be more a non-physicist as myself. So please permit me my ramblings so I can better understand where I must be wrong.

    Here’s a thought experiment. Imagine a planet being instantly created in a universe with nothing else in it. Would it slowly lose mass though its gravitational field? Is mass preserved in a universe where there is an abundance of matter where gravitational energy is mutually exchanged?

    Which leads to the bigger question… the discovery that the expansion of the universe is not slowing but accelerating has raised the question of some repulsive force in matter. But it occurred to yesterday whether this acceleration can be due to a radiational loss of mass in these galaxies as they fly further apart. Observationally how would one tell the difference? Empirically how would this be tested? That the orbits of stars on the outer bands of a galaxy might show signs of accelerating?

    Thanks in advance for all your patience ;-)
  2. jcsd
  3. Jul 26, 2008 #2


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    Staff: Mentor

    Welcome to PF.

    Gravitational fields do not consume energy, so there is no energy being radiated away. If you had two point masses in orbit of each other, they'd orbit forever and the energy level of the system would always be constant. This is from Newton's 1st law and the law of conservation of energy.
  4. Jul 26, 2008 #3
    Thanks for the welcome Russ. I was thinking of a process along the lines of Hawking Radiation.
  5. Jul 30, 2008 #4
    the repulsive force of matter, well do you mean dark energy or hawking radiation? I am pretty sure they are different. to answer to your first question, I believe hawking radiation does not directly effect a lone planet in a vacuum, BUT if the universe it was in was accelerating then the matter of the planet would eventually be ripped apart by the repulsion of Dark energy aka spatial expansion, which is a mysterious special type of non-zero energy .

    I could be wrong though SOOOO here is the wiki definition of Hawking radiation: "By this process the black hole loses mass, and to an outside observer it would appear that the black hole has just emitted a particle. In reality, the process is a quantum tunneling effect, whereby particle-antiparticle pairs will form from the vacuum, and one will tunnel outside the event horizon."

    I am pretty sure Hawkings "radiation" effects all particle-antiparticle pairs inthe vaccum trapped behing the event horizon of black holes.

    on a side note; is it possible that the effect of dark energy could be an effect of particles with mass "sinking" at the same rate into spacetime rather than being thought of as spacetime being stretched (aka expanding) between them?
  6. Jul 30, 2008 #5
    Since the universe is continualy expanding, does that mean the TOTAL energy in the entire universe, or maybe even EP is increasing? Just a random question i just made up
    but then again, energy is unlimited isnt it? or if everything could move at the speed of light....hmmm i dunno what im saying, lol
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