Dark Energy Might Not Exist

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Dark Energy Might Not Exist

#1  Postby the_5th_ape » Apr 02, 2017 6:15 pm

Enigmatic dark energy, thought to make up 68% of the universe, may not exist at all, according to a Hungarian-American team. The researchers believe that standard models of the universe fail to take account of its changing structure, but that once this is done the need for dark energy disappears.


https://www.sciencedaily.com/releases/2 ... 115254.htm
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Re: Dark Energy Might Not Exist

#2  Postby Alan B » Apr 02, 2017 6:43 pm

Oh, yes he does! :snooty: :whistle:

Sorry! Couldn't resist that.

Fascinating article. Now, if true, where does that leave Dark Matter?
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Re: Dark Energy Might Not Exist

#3  Postby Dark energy » Apr 03, 2017 12:16 am

kkk.
And."
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Re: Dark Energy Might Not Exist

#4  Postby newolder » Sep 06, 2018 12:25 pm

More on the same topic from Oxford, UK, researchers...
Horizon, the EU Research & Innovation Magazine
and associated arxiv post from August 14th.
Recent observations reveal a bulk flow in the local Universe which is faster and extends to larger scales than is expected around a typical observer in the standard ΛCDM cosmology. The deceleration parameter q0 derived from local observations is then expected to show a scale-dependent dipolar modulation. From a maximum likelihood analysis of the Joint Lightcurve Analysis (JLA) catalogue of Type Ia supernovae we do find such a dipole in q0 extending out to z∼0.2, with a magnitude comparable to its monopole. Although not statistically significant in current data, such a dipole must be allowed for, especially in analysing surveys with incomplete sky coverage such as JLA and its successor Pantheon; out of 740 (1048) SNe IA in the JLA (Pantheon) catalogue, 632 (890) are in the hemisphere opposite to the direction of bulk flow for which their redshifts have been corrected. However when we do so, the monopole component of q0, which has been widely ascribed to a cosmological constant (dark energy), drops in statistical significance and becomes consistent with zero at 2σ (95\% c.l.). This suggests that the apparent acceleration of the expansion rate deduced from supernovae may be an artefact of our bulk flow.

Basically, the suggestion is that our local (within 600 million light years, or so) flow wrt the rest of the universe accounts for much of the hitherto observed acceleration.

Also, there are reports today of a new supernovae study to be published tomorrow that highlight further the tension in measurements of the Hubble constant, H0, made by the Planck consortium published earlier this year.

Intrigue every which way we look...
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Re: Dark Energy Might Not Exist

#5  Postby felltoearth » Sep 06, 2018 9:49 pm

Does that mean there is more mass in our local area?
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Re: Dark Energy Might Not Exist

#6  Postby laklak » Sep 06, 2018 10:13 pm

Yeah, but she's over in Swaziland at the moment.
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Re: Dark Energy Might Not Exist

#7  Postby felltoearth » Sep 07, 2018 1:45 am

Ouch!
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Re: Dark Energy Might Not Exist

#8  Postby newolder » Sep 07, 2018 8:39 am

This study does not make a claim that there is less mass hereabouts, regardless of any population drift, but that the requirement for dark energy (whatever that may be) is reduced to the point of statistical insignificance. Co-author Prof Sarker, a particle physicist, notes in the interview:
For astronomers, a three-sigma result may be interesting, but for a particle physicist like me it’s not worth getting out of bed for.
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Re: Dark Energy Might Not Exist

#9  Postby Hermit » Sep 07, 2018 8:53 am

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Re: Dark Energy Might Not Exist

#10  Postby newolder » Sep 07, 2018 9:27 am

Perhaps the penalty for such altar-cation is to be shrunk to small size? :dunno:
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Re: Dark Energy Might Not Exist

#11  Postby truelgbt » Sep 27, 2018 12:48 am

Goes to show how 'facts' can change so rapidly. Not surprised at all.

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Re: Dark Energy Might Not Exist

#12  Postby laklak » Sep 27, 2018 1:52 am

Yeah, science is funny that way.
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Re: Dark Energy Might Not Exist

#13  Postby newolder » Oct 14, 2019 7:59 am

Upon reinvestigation of the Leavitt law of Cepheid variable star period versus luminosity/distance for Milky Way Cepheids (and companion stars) from Gaia data release 2, a study in Astronomy & Astrophysics on October 11th finds that the Hubble constant tension between the "distance ladder" methods and those employed on cosmic microwave background measurements has disappeared.

The Leavitt law of Milky Way Cepheids from Gaia DR2 static companion parallaxes

... the Hubble constant results in a value of 69 ± 2 km s−1 Mpc−1, statistically compatible with the Planck Collaboration et al. (2018) estimate.


Quoted earlier in the work as:

The value H = 67.4 ± 0.5 km s−1 Mpc−1 derived from the Planck CMB data by Planck Collaboration et al. (2018), assuming a ΛCDM cosmology.


Sighs of relief heard even across the Twittersphere.

Just to add for topic relevance: The ΛCDM cosmology model used in the CMBR analysis yields 69% of the universe to be comprised of dark energy, Λ, 26% to be CDM (cold dark matter) and 5% "ordinary" stuff - see, e.g. Jim Peebles.
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