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Thread: No dark energy???

  1. #1 No dark energy??? 
    Forum Radioactive Isotope skeptic's Avatar
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    Reference :new Scientist, 28 June 2014, page 33

    Is there no dark energy?

    This might be possible if the universe was not, in fact, homogeneous on large scales. We might be part of a low density 'bubble' a few billion light years across, surrounded by higher density zones. In that case, our bubble would accelerate outwards due to the surrounding gravitational pull, thus simulating dark energy.


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    Quote Originally Posted by skeptic View Post
    Reference :new Scientist, 28 June 2014, page 33

    Is there no dark energy?

    This might be possible if the universe was not, in fact, homogeneous on large scales. We might be part of a low density 'bubble' a few billion light years across, surrounded by higher density zones. In that case, our bubble would accelerate outwards due to the surrounding gravitational pull, thus simulating dark energy.
    There is no evidence for your conjecture.


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    Forum Professor Daecon's Avatar
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    Hmm, if that was a viable hypothesis then would what could be the cause of the bubble? Would there be more than one bubble? I've not read the New Scientist article, is there a link to it online?
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    Forum Masters Degree Implicate Order's Avatar
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    Quote Originally Posted by skeptic View Post
    Reference :new Scientist, 28 June 2014, page 33

    Is there no dark energy?

    This might be possible if the universe was not, in fact, homogeneous on large scales. We might be part of a low density 'bubble' a few billion light years across, surrounded by higher density zones. In that case, our bubble would accelerate outwards due to the surrounding gravitational pull, thus simulating dark energy.
    Quite interesting. The assumption of universal homogeneity and isotropy once again comes under the testing hammer. Given recent WMAP anomalies and the current controversy surrounding the low quadrupole argument I will be very interested to see whether these standard assumptions hold over the longer term. The low quadrople argument rests on the basis that the previous assumption in Standard Cosmology that temperature fluctuations in the CMB should pervade the sky appears to not be the case. Both COBE and WMAP independently verify that there are virtually no fluctuations at angular scales larger than 60 degrees. One possible explanation is that spacetime simply isn't large enough to support such large scale fluctuations which puts an argument towards the universe terminating at the hubble boundary (which supports the 60 degree argument). There are some tempting but very speculative notions that are arguing this case.

    Paul Steinhardt and Neil Turok question the assumptions of universal homogenity and isotropy in their cyclic universe hypothesis given that quite clearly present day observers do not occupy a bog standard position in this universe in our local cluster of galaxies which is significantly higher than the average universal density proposed. This mere fact is of course going to have an effect on our observations. The question is whether you need to discount this finding or not.

    Despite these murmurs I am not sure whether or not we can disregard that dark energy exists. Certainly zero point energy is a factor we must take into account when dealing with HUP but whether this is the mysterious dark energy.......who knows. I suppose time will tell?

    ......but best to wait until further confirmation before throwing out the baby with the bath oil.
    Last edited by Implicate Order; July 4th, 2014 at 11:06 PM.
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    Quote Originally Posted by mathman View Post

    There is no evidence for your conjecture.
    Not, of course, my conjecture. My mind is not educated enough for cosmological speculation. However, others may come up with ideas that I can report. This is from a report in the latest New Scientist, which is not yet on line. Give it a few weeks and they will put the article up there for everyone.
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