Science > Physics > Does WMAP prove or disprove whether the cosmological constant varies with time?
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Science > Physics |
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"" |
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25 Mar 2006 01:19:48 AM |
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Does WMAP prove or disprove whether the cosmological constant varies with time? |
At present, Lambda has the value of the horizon.
Papers like http://www.arxiv.org/abs/hep-th/0603133
argue that this has always been the case,
due to holography.
But if that is so, Lambda changes with time,
and thus should be different in the distant past.
Can WMAP prove or disprove this?
Frank
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| User: "Sam Wormley" |
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| Title: Re: Does WMAP prove or disprove whether the cosmological constantvaries with time? |
25 Mar 2006 01:33:18 AM |
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wrote:
At present, Lambda has the value of the horizon.
Papers like http://www.arxiv.org/abs/hep-th/0603133
argue that this has always been the case,
due to holography.
But if that is so, Lambda changes with time,
and thus should be different in the distant past.
Can WMAP prove or disprove this?
Frank
WMAP data doesn't address the values of the cosmological constant.
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| User: "" |
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| Title: Re: Does WMAP prove or disprove whether the cosmological constant varies with time? |
25 Mar 2006 04:48:06 AM |
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Sam Wormley wrote:
frank_k_sheldon@yahoo.co.uk wrote:
At present, Lambda has the value of the horizon.
Papers like http://www.arxiv.org/abs/hep-th/0603133
argue that this has always been the case,
due to holography.
But if that is so, Lambda changes with time,
and thus should be different in the distant past.
Can WMAP prove or disprove this?
WMAP data doesn't address the values of the cosmological constant.
Well, let me rephrase the question in WMAP data:
Does WMAP show whether the dark energy content they measure
is different at present (or near us) from the past (or distant from
us)?
Frank
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| User: "John Bailey" |
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| Title: Re: Does WMAP prove or disprove whether the cosmological constant varies with time? |
25 Mar 2006 09:15:31 AM |
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On 25 Mar 2006 02:48:06 -0800, wrote:
Does WMAP show whether the dark energy content they measure
is different at present (or near us) from the past (or distant from
us)?
I think you want:
http://xyz.lanl.gov/PS_cache/astro-ph/pdf/0603/0603539.pdf
Inflation models after WMAP year three by Alabidi and Lyth
(quoting) For the first time, a large fraction of the
models are ruled out at more than 3 sigma.
Also relevant:
http://lanl.arxiv.org/abs/astro-ph/0603449
Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results:
Implications for Cosmology by D. N. Spergel, R. Bean, O. Dore', M. R.
Nolta, C. L. Bennett, G. Hinshaw, N. Jarosik, E. Komatsu, L. Page, H.
V. Peiris, L. Verde, C. Barnes, M. Halpern, R. S. Hill, A. Kogut, M.
Limon, S. S. Meyer, N. Odegard, G. S. Tucker, J. L. Weiland, E.
Wollack and E. L. Wright
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| User: "" |
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| Title: Re: Does WMAP prove or disprove whether the cosmological constant varies with time? |
25 Mar 2006 11:50:13 AM |
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John Bailey wrote:
On 25 Mar 2006 02:48:06 -0800, wrote:
Does WMAP show whether the dark energy content they measure
is different at present (or near us) from the past (or distant from
us)?
I think you want:
http://xyz.lanl.gov/PS_cache/astro-ph/pdf/0603/0603539.pdf
Also relevant:
http://lanl.arxiv.org/abs/astro-ph/0603449
I am not a cosmologist, but the original question does not
seem to be answered in either paper. Or am I wrong?
Frank
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| User: "John Bailey" |
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| Title: Re: Does WMAP prove or disprove whether the cosmological constant varies with time? |
25 Mar 2006 01:09:37 PM |
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On 25 Mar 2006 09:50:13 -0800, wrote:
Sam Wormley wrote:
WMAP data doesn't address the values of the cosmological constant.
Well, let me rephrase the question in WMAP data:
Does WMAP show whether the dark energy content they measure
is different at present (or near us) from the past (or distant from
us)?
I think you want:
http://xyz.lanl.gov/PS_cache/astro-ph/pdf/0603/0603539.pdf
Also relevant:
http://lanl.arxiv.org/abs/astro-ph/0603449
I am not a cosmologist, but the original question does not
seem to be answered in either paper. Or am I wrong?
Indeed it is not answered. My post responded to Wormley's assertion
that WMAP did not address values of the cosmological constant or (by
implication) dark energy. I also intended to give a reference to the
most recent, authoritative efforts to let the community know their
first order conclusions from the WMAP data. It is my impression that
WMAP data serves to support or suppress multiple cosmological models,
thus indirectly answering such questions. Given the suprisingly early
availability of articles from WMAP leaders such as I cited, it would
be amazing if they could include comment on theories such as that
advanced by Balazs and Szapudi.
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| User: "=?UTF-8?Q?Jeff=E2=80=A6Relf?=" |
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| Title: SNLS's prelimiary data, released November 22nd. |
01 Apr 2006 03:09:30 AM |
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Hi Frank_K_Sheldon, WMAP merely pins down how much dark energy there is,
within a 5 percent error, and it's March 17th data shows only polerizations
from dissipation, and not from the gravity waves you'd expect to see
if, absurdly, our entire cosmos had popped into existence
in a thrillionth of a second... along with flying pigs.
It's SNLS's prelimiary data, released November 22nd,
that tells us that that dark energy is, in fact,
General_Relativity's cosmological constant, lambda.
With only 10 percent of the expected data, and a 10 percent margin of error,
lambda is appears to be quite constant for the last 12 billion years or so.
Like many others, I expect that lambda to be perfectly constant,
going back forever, but a WMAP-like satellite looking at standard candles
would really help support that notion.
As Hawking says, the cosmos likely has no beginning or end.
The universe has just always been dissipating, I posit,
and entropy is the measure of cosmic time, Space_Time_Entropy.
The 5D shape of the cosmos, Space_Time_Entropy,
can be imagined as a 2D hyperbola
or a 3D horn with an infinitely long mouthpiece and flange.
Because the cosmos has no center of gravity, it's 4D shape, i.e. Space_Time,
-- not 3D Space or 5D Space_Time_Entropy, mind you --,
is flat, like a straight 2D line.
So that's where gravity came from, and where it's going.
The net mass-energy of the cosmos is known to be _Negative_,
a.k.a. General_Relativity's lambda, a.k.a. GR's cosmological _Constant_,
a.k.a. dark energy, a.k.a. negative pressure... etc.
It takes energy to maintain a vacuum... it's an energy consumer.
e=mcc means: Negative_Pressure = Negative_Energy
Hence, vacuums are gravitationally repulsive and
a perfect vacuum would consume all the energy in the cosmos, and then some.
Likewise, infinite density equates to infinite acceleration,
and, therefore, infinite Unruh radiation,
....emitting more energy than currently exists in the cosmos, and then some.
While the spin of the earth and it's path around the sun are well known,
a priori, the spin of a photon and its path are _Never_ fully known,
even after it's, ahem, measured.
So... The key to understanding cosmology and TOEs is noting that
nothing is intrinsically random; instead, some things are simply unknown,
given _Today_'s best observations/theories.
The postulates above refine GR, in my opinion.
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