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B Can this be another reason for dark energy?

  1. Jul 8, 2017 #1
    Suppose the initial force and energy bursting out during big bang was very huge . The matter just after big bang would have been very close , so the gravitational attraction would have been very high , which would have caused the acceleration produced by big bang to decrease . As time increased , gravity between cosmological objects decreased ( due to increase of distance caused by initial acceleration of big bang ) . As gravity is the only major force between objects getting apart at a constant velocity , and it is decreasing , then an observer would notice that the objects are accelerating apart . That is what we know today !! . I just want to ask if dark energy is nothing but the initial force of big bang which seems to accelerate due to decrease of gravity ?

    Ps – Sorry for my bad explanation skill :)
  2. jcsd
  3. Jul 8, 2017 #2


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    Gold Member

    No it is not. There would be NO acceleration due to the force of the BB (I mean, think about it) which is why, when the acceleration was first noticed (and attributed to the mysterious "dark energy") everyone was quite surprised.

    Also, you might find it instructional to stop and think about whether you have come up with an idea that has eluded THOUSANDS of serious professional physicists.
  4. Jul 8, 2017 #3


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    Staff: Mentor

    Welcome to the PF. :smile:

    Please keep in mind that we do not discuss personal theories here on the PF. It is fine to phrase it in the form of a question, but proposing new mechanisms for observed phenomena is not allowed. Thanks.
  5. Jul 8, 2017 #4
    Your hypothesis would not result in accelerating expansion,
    It would result in an expansion rate that gradually decreases over time, and could possibly reverse in the future.
    Prior to the 1990's this is what many astronomers expected they would observe when a new generation of more powerful telescopes went in to service.
    Instead the observations indicated that the acceleration rate actually is increasing over time.
    That implies additional energy coming into existence after the initial big bang, and that's what got the name dark energy.
    Last edited: Jul 8, 2017
  6. Jul 9, 2017 #5
    You mean expanding with a decreasing rate.
    That would be the case if there was no dark energy. Then, the accelerating rate (or better said "expansion rate") would be decreasing.
    Thus we just happen to live in that time era and age of the universe (i.e. ≅ 13.8 billion years after the big bang) where dark energy prevails over gravity and that's why we observe accelerating expansion of the universe. (That effect had already started roughly 5 billion years ago, or approximayelly 8.8 billion years after the big bang ...)

    Note: current "precise" measurement of the age of the universe is (13.799 ± 0.021) billion (i.e. 109) years.
    ( https://en.m.wikipedia.org/wiki/Age_of_the_universe )
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