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Thread: No dark energy?

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    No dark energy?

    https://phys.org/news/2020-01-eviden...very-dark.html
    New observations and analysis made by a team of astronomers at Yonsei University (Seoul, South Korea), together with their collaborators at Lyon University and KASI, show, however, that this key assumption is most likely in error. The team has performed very high-quality (signal-to-noise ratio ~175) spectroscopic observations to cover most of the reported nearby early-type host galaxies of SN Ia, from which they obtained the most direct and reliable measurements of population ages for these host galaxies. They find a significant correlation between SN luminosity and stellar population age at a 99.5 percent confidence level. As such, this is the most direct and stringent test ever made for the luminosity evolution of SN Ia. Since SN progenitors in host galaxies are getting younger with redshift (look-back time), this result inevitably indicates a serious systematic bias with redshift in SN cosmology. Taken at face values, the luminosity evolution of SN is significant enough to question the very existence of dark energy. When the luminosity evolution of SN is properly taken into account, the team found that the evidence for the existence of dark energy simply goes away (see Figure 1).
    SHARKS (crossed out) MONGEESE (sic) WITH FRICKIN' LASER BEAMS ATTACHED TO THEIR HEADS

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    They find a significant correlation between SN luminosity and stellar population age....
    How do they convert stellar population age into a reasonably good estimate for distance?
    Everyone is entitled to his own opinion, but not his own facts.

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    Quote Originally Posted by Cougar View Post
    How do they convert stellar population age into a reasonably good estimate for distance?
    Here is the 51 page report telling how:
    https://arxiv.org/pdf/1912.04903.pdf
    SHARKS (crossed out) MONGEESE (sic) WITH FRICKIN' LASER BEAMS ATTACHED TO THEIR HEADS

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    Quote Originally Posted by Cougar View Post
    How do they convert stellar population age into a reasonably good estimate for distance?
    Here is the 51 page report telling how:
    https://arxiv.org/pdf/1912.04903.pdf
    SHARKS (crossed out) MONGEESE (sic) WITH FRICKIN' LASER BEAMS ATTACHED TO THEIR HEADS

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    Sorry, it blanked out when I tried to post my reply and I thought I had to try again.
    SHARKS (crossed out) MONGEESE (sic) WITH FRICKIN' LASER BEAMS ATTACHED TO THEIR HEADS

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    Quote Originally Posted by Tom Mazanec View Post
    Here is the 51 page report telling how:
    https://arxiv.org/pdf/1912.04903.pdf
    I'm curious about an answer to Cougar's question. "Distance" is only mentioned a handful of times and "Cepheid" zero.
    We know time flies, we just can't see its wings.

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    It's worrisome, but note that if the acceleration goes away, we have a real problem understanding the history of the expansion with only 30% of the critical mass. So one must do more than just get rid of the acceleration, one must tell a complete story of the full history, using only the matter. The one thing that everyone expected was for the spatial curvature to be flat, because anything other than flat is unstable and evolves quickly, making it very difficult to get a long-lived universe like ours. Dark energy was doing a lot more than accelerating the expansion, it was allowing space to be flat even though there was not enough dark matter to do it. My guess is, if they get rid of dark energy, they will have to start looking for about 3 times more dark matter than they have already! So it's not like you could say, "well there goes dark energy, I guess dark matter will be next..." It's quite the opposite. I wouldn't be surprised if people find flaws in this new analysis, though apparently it is a very important dataset.
    Last edited by Ken G; 2020-Jan-06 at 11:02 PM.

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    Quote Originally Posted by Ken G View Post
    It's worrisome, but note that if the acceleration goes away, we have a real problem understanding the history of the expansion with only 30% of the critical mass. So one must do more than just get rid of the acceleration, one must tell a complete story of the full history, using only the matter. The one thing that everyone expected was for the spatial curvature to be flat, because anything other than flat is unstable and evolves quickly, making it very difficult to get a long-lived universe like ours. Dark energy was doing a lot more than accelerating the expansion, it was allowing space to be flat even though there was not enough dark matter to do it. My guess is, if they get rid of dark energy, they will have to start looking for about 3 times more dark matter than they have already! So it's not like you could say, "well there goes dark energy, I guess dark matter will be next..." It's quite the opposite. I wouldn't be surprised if people find flaws in this new analysis, though apparently it is a very important dataset.
    I agree that dark energy exists in some form, but I don't think it means, what we thought it means. Ditto for inflation.
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    Well, if the 2011 Nobel Prize was wrong, it was wrong. IIRC they once gave a Nobel Prize for sticking an ice pick in the brain.
    More Dark Matter would be almost as interesting as Dark Energy. I suppose it would have to be distributed in such a way that galactic rotation would not be changed by tripling its mass.
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    No surprise that there are a lot of papers examining the values of various cosmological parameters; also no suprise that those which report problems of one kind or another get faaar more airtime than those which report consistency.

    The paper being reported by phys.org is yet another "problem" paper. And, like all such so far, it will be closely examined; who knows if it will withstand close scutiny. My own skim of it suggests there are several systematics which could be problematic.

    I think that it will be several more years before the dust settles.

    The phys.org article has yet another weakness: there are several other, independent, methods of estimating the values of cosmological parameters, methods not mentioned. True, these other methods do not yet give particularly robust results ... but of interest is that those estimates are consistent with the Planck CMB ones, say.

    It's no surprise that SNe 1a's are what a lot of astronomers focus on ... no one is planning to independently check the Planck results (say), and such a check of the BAO ones is far more difficult than going after 1a's and its standardization methods.

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    Quote Originally Posted by Tom Mazanec View Post
    Well, if the 2011 Nobel Prize was wrong, it was wrong. IIRC they once gave a Nobel Prize for sticking an ice pick in the brain.
    No, they gave a Nobel prize for the invention of leucotomy, which was carried out with a specific surgical instrument called a leucotome. Although it's viewed with ill-informed outrage and derision now, it needs to be understood in the context of its time.

    Grant Hutchison

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    Quote Originally Posted by Ken G View Post
    ...note that if the acceleration goes away, we have a real problem understanding the history of the expansion with only 30% of the critical mass....
    Right - the geometry of space has been measured to be flat, and surveys of all the baryonic plus dark matter only reach about 30% of the mass needed to make it flat. So "doing away with" dark energy would require finding 70% of the universe's mass that is not dark energy or any other known mass....
    Everyone is entitled to his own opinion, but not his own facts.

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    Quote Originally Posted by Ken G View Post
    It's worrisome, but note that if the acceleration goes away, we have a real problem understanding the history of the expansion with only 30% of the critical mass.
    Would this also put the big glitch variance closer to 10121?
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