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New evidence shows that the key assumption made in the discovery of dark energy is in error:
The most direct and strongest evidence for the accelerating universe with dark energy is provided by the distance measurements using type Ia supernovae (SN Ia) for the galaxies at high redshift. This result is based on the assumption that the corrected luminosity of SN Ia through the empirical standardization would not evolve with redshift.
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).
Commenting on the result, Prof. Young-Wook Lee (Yonsei Univ., Seoul), who led the project said, "Quoting Carl Sagan, extraordinary claims require extraordinary evidence, but I am not sure we have such extraordinary evidence for dark energy. Our result illustrates that dark energy from SN cosmology, which led to the 2011 Nobel Prize in Physics, might be an artifact of a fragile and false assumption."
More information:
Early-Type Host Galaxies of Type Ia Supernovae. II. Evidence for Luminosity Evolution in Supernova Cosmology, Astrophysical Journalarxiv.org/abs/1912.04903
Journal information: Astrophysical Journal
(Score: 4, Insightful) by PiMuNu on Thursday January 09 2020, @09:54AM (10 children)
> universe-shaking adjustments to phyics
No! Maybe universe-shaking adjustments to your preconceived notions of what physics should be.
Your preconceived notions require that cosmological constant is 0, but this is not required by any physical principle. So we should let it float, and then see what value best fits *the data*.
It is "easier" if the earth is at the centre of the universe.
It is "easier" if Galilean relativity is correct.
It is "easier" if there is no dark energy.
But we should always modify the theory to fit observation, not the other way around.
(Score: 0) by Anonymous Coward on Thursday January 09 2020, @01:55PM
True, but the constant was only invented to save the static universe hypothesis. A hypothesis that Hubble showed was incorrect, when he showed that the universe was expanding (as the constant-less equations showed was likely).
Only later did they resurrect this constant when the data seemed to show that the universal expansion was accelerating.
(Score: 4, Informative) by Coward, Anonymous on Thursday January 09 2020, @03:19PM (6 children)
In your other examples, there was no way to square the observations with the theory, or make the theory hang together consistently. That's why the old theories failed and were replaced. For dark energy, the "observations" are not observations at all, but belief that magic sauce "standardization" can turn supernovae into standard candles of known brightness. Rather than admitting that these standardization adjustments are a weak basis for the follow-on theory of dark energy, cosmologists have gone all-in.
This wouldn't be the first time that systematic errors were underestimated [stackexchange.com] and for sociological reasons, physicists held on to a wrong conclusion for decades.
(Score: 2) by DannyB on Thursday January 09 2020, @03:35PM
Bring back the Aether [wikipedia.org] (aka, Luminiferous aether [wikipedia.org])
The lower I set my standards the more accomplishments I have.
(Score: 2) by PiMuNu on Thursday January 09 2020, @08:26PM (4 children)
I am all for dropping dark energy if the data turns out not to support it because of a wrong systematic error (or any other reason).
I just object to the grandparent preferring this theory or that theory on the grounds of prettiness or some other subjective thing.
(Score: 2) by Coward, Anonymous on Sunday January 12 2020, @07:54AM (3 children)
Physics is about describing the world with the fewest possible terms. So yes, that does imply a preference for an explanation of supernova magnitudes that does not rely on the cosmological constant. Einstein didn't like [scitation.org] the constant either.
(Score: 2) by PiMuNu on Monday January 13 2020, @10:07AM (2 children)
> Physics is about describing the world with the fewest possible terms.
That's a pretty big statement.
1. We have been lucky so far that the reductionist approach works. But there is no reason that it should.
2. We know General Relativity is incomplete. E.g. vacuum energy can come into play which is not well understood. A later iteration of standard model may constrain cosmological constant to non-zero value.
So in general if the data doesn't support 0 cosmological constant then we have to follow the data.
There is a slight subtlety, which maybe you don't know? General Relativity is built on a couple of axioms:
1. speed of light is true for gravity
2. gravitation mass is the same as inertial mass - i.e. force from a planet is bigger because it has more "gravitation mass" and force required to push a truck is big because it has more "inertial mass"
There axioms constrain lots of things, but don't constrain the cosmological constant.
> Einstein didn't like the constant either.
I know, but it doesn't mean it is wrong. Falling back on [famous physicist] is a lazy argument. I think there should be a physics equivalent of Godwin Rule!
(Score: 3, Insightful) by Coward, Anonymous on Monday January 13 2020, @02:50PM (1 child)
Every new term in physics is worth a Nobel Prize. If only to protect physics from human selfishness, skepticism against new claims is required.
(Score: 2) by PiMuNu on Monday January 13 2020, @03:19PM
> skepticism against new claims is required.
Can't argue with that; and given the nature of TFA, justified!
(Score: 1) by unhandyandy on Friday January 10 2020, @03:47AM (1 child)
"Your preconceived notions require that cosmological constant is 0"
No, my preconceived notion is that we haven't overlooked 68% of the universe over the 10000 years of recorded history. That notion may be wrong, but it requires more evidence to set it aside than has been produced.
(Score: 2) by PiMuNu on Friday January 10 2020, @10:50AM
> over the 10000 years of recorded history.
That is an insane point of view, are you a troll?
We overlooked physics for about 9600 years of recorded history.
We overlooked any theoretical understanding of gravitation for about 9700 years of recorded history.
We overlooked any theoretical understanding of electromagnetism for about 9800 years of recorded history.
We overlooked cosmology/general relativity for about 9900 years of recorded history.
Do you deny physics? Perhaps you just deny general relativity?