Evidence record

What is most of the universe made of?

Every sentence on the exploration belongs to at least one claim below. Each says what kind of statement it is, what it rests on, what the evidence does not establish, and how far it was checked. Nothing here is a score, and none of it is a verdict on a belief or a theory.

Last checked 24 September 2026.

Source checked: 52
A judgement, not a fact: 8
Presented as open: 1

If something here is wrong, misquoted, out of date or unfair, write to support@unknownoceans.com and give the claim number, which does not change.

What the question takes for granted

A question about what the universe contains, asked of a budget that is measured precisely and identified only in part. Its wording, "made of", leans towards substances; one live answer is that some of what is missing is a change to gravity rather than a substance.

Most of the universe’s energy content is not ordinary matter
Established
Within the standard cosmological model, Planck’s parameters put ordinary matter at about 5 per cent.
What is missing is something the universe is made of
Contested
Dark matter as a substance is the mainstream view; modified gravity keeps a minority case. Dark energy may be a property of space, a field, or a change to gravity.
General relativity holds on the scales where the missing mass and energy are inferred
Contested
Every gravitational inference of dark matter assumes it, as does the case that acceleration needs a new energy; the PDG reviews say so.

How the question is labelled

Claim: Dark matter and dark energy

Kind: Framing. Signposting. It asserts nothing a source could check.

Claim: Dark matter

Kind: Framing. Signposting. It asserts nothing a source could check.

The question

Claim: Everything we can see accounts for about five percent of it.

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

Planck measures the baryon density as Ωbh² = 0.02237 with h = 0.674, which is 0.049 of the critical density: about 5 per cent.

Supports
Planck 2018 results. VI. Cosmological parameterssection 3.5, equation 24
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: Despite comprising less than a sixth of the total matter content
Supports
Planck 2018 results. VI. Cosmological parameterssection 3.5, equations 22 and 23
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: The matter density is well constrained to be Ωₘh² = 0.1430± 0.0011 (68 %, Planck TT,TE,EE +lowE+lensing). (22) The matter mostly consists of cold dark matter
Notation restored: Subscripts and superscripts restored as the arXiv PDF (1807.06209v4) typesets them, read from glyph positions 2026-09-24; the abstract on arXiv gives H_0 and Ω_m the same way. The text as extracted reads: The matter density is well constrained to be Ωmh2 = 0.1430± 0.0011 (68 %, Planck TT,TE,EE +lowE+lensing). (22) The matter mostly consists of cold dark matter
Supports
Planck 2018 results. VI. Cosmological parametersabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: Hubble constant H₀ = (67.4±0.5) km s⁻¹ Mpc⁻¹; matter density parameter Ωₘ = 0.315±0.007
Notation restored: Subscripts and superscripts restored as the arXiv PDF (1807.06209v4) typesets them, read from glyph positions 2026-09-24; the abstract on arXiv gives H_0 and Ω_m the same way. The text as extracted reads: Hubble constant H0 = (67.4±0.5) km s−1Mpc−1; matter density parameterΩm = 0.315±0.007
Supports
Dark Mattersection "What is Dark Matter?"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: From stars and galaxies to the shoes on your feet, ordinary matter makes up everything we can see in the universe

What this does not establish

"Everything we can see" stands for all ordinary matter, which is about 5 per cent whether or not it has been seen: much of it is diffuse gas. The figure is inferred within the standard cosmological model.

Later work looked for

PDG Review of Particle Physics, Dark Matter (revised August 2025): the same budget; Crossref, 2023 on, "cosmological parameters baryon density CMB": nothing that changes it.

Claim 3 · checked 24 September 2026 · AI-assisted audit

Claim: Galaxies, stars, planets, dust and every particle in the Standard Model together make up roughly 5% of the energy content of the universe.

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

Supports
Planck 2018 results. VI. Cosmological parameterssection 3.5, equation 24
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: Despite comprising less than a sixth of the total matter content
Supports
Planck 2018 results. VI. Cosmological parameterssection 3.5, equations 22 and 23
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: The matter density is well constrained to be Ωₘh² = 0.1430± 0.0011 (68 %, Planck TT,TE,EE +lowE+lensing). (22) The matter mostly consists of cold dark matter
Notation restored: Subscripts and superscripts restored as the arXiv PDF (1807.06209v4) typesets them, read from glyph positions 2026-09-24; the abstract on arXiv gives H_0 and Ω_m the same way. The text as extracted reads: The matter density is well constrained to be Ωmh2 = 0.1430± 0.0011 (68 %, Planck TT,TE,EE +lowE+lensing). (22) The matter mostly consists of cold dark matter
Supports
Planck 2018 results. VI. Cosmological parametersabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: Hubble constant H₀ = (67.4±0.5) km s⁻¹ Mpc⁻¹; matter density parameter Ωₘ = 0.315±0.007
Notation restored: Subscripts and superscripts restored as the arXiv PDF (1807.06209v4) typesets them, read from glyph positions 2026-09-24; the abstract on arXiv gives H_0 and Ω_m the same way. The text as extracted reads: Hubble constant H0 = (67.4±0.5) km s−1Mpc−1; matter density parameterΩm = 0.315±0.007
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: The nature of only a small fraction, between at least 0.5% (given neutrino os-cillations) and at most 1.6% (from combined cosmological constraints), of the non-baryonic matter content of the universe is known: the three Standard Model neutrinos

What this does not establish

Ordinary matter is about 4.9 per cent. The Standard Model’s neutrinos add a little more, between 0.5 and 1.6 per cent of the non-baryonic matter by the PDG review’s figures, which is why the page says "roughly". Inferred within the standard cosmological model.

Later work looked for

PDG dark matter review, revised August 2025: the same budget; nothing that changes it.

Claim 4 · checked 24 September 2026 · AI-assisted audit

Claim: The other 95% has a name, a measured quantity, and no identification.

Kind: What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: The fundamental makeup of the large majority of the DM is, as of yet, unknown.
Supports
Dark Energy (Review of Particle Physics, chapter 28)section 28.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: The title of this article follows the common but inexact usage of “dark energy” as a catch-all term for the origin of cosmic acceleration, regardless of whether it arises from a new form of energy or a modification of GR.
Supports
Planck 2018 results. VI. Cosmological parameterssection 3.2, equation 15
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: a constraint on Ωₘ translates directly into a constraint on the dark-energy density parameter, giving ΩΛ = 0.6847± 0.0073
Notation restored: Subscripts and superscripts restored as the arXiv PDF (1807.06209v4) typesets them, read from glyph positions 2026-09-24; the abstract on arXiv gives H_0 and Ω_m the same way. The text as extracted reads: a constraint on Ωm translates directly into a constraint on the dark-energy density parameter, giving ΩΛ = 0.6847± 0.0073

What this does not establish

A small part of the dark matter is known: Standard Model neutrinos, about 1 per cent of it. Whether dark energy is a new kind of energy at all, or a change to gravity, is open.

Later work looked for

PDG reviews revised August 2025: dark matter’s makeup still unknown, dark energy still a catch-all name.

Claim 5 · checked 24 September 2026 · AI-assisted audit

Claim: A gap at the edges of physics would be one thing. This is the majority of the subject.

Kind: This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review: A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

The page’s own framing of the figures above.

Claim 6 · checked 24 September 2026 · AI-assisted audit

Claim: Two separate discrepancies, found decades apart by completely different methods, both point the same way

Kind: Historical claim. A statement about the past that historical evidence can test.
Review: Source checked. The cited passage was read, and it says this.

The first is the motion of galaxies and stars, from the 1930s and 1970s; the second is the dimming of distant supernovae, from 1998.

Supports
Dark Mattersection "Discovering Dark Matter"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: In 1933, Swiss-born astronomer Fritz Zwicky published a paper in which he described an anomaly he observed studying a cluster of galaxies known as the Coma Cluster. ... That changed in the 1970s when American astronomer Vera Rubin observed this "missing matter" problem in spiral galaxies.
Supports
What is Dark Energy? Inside Our Accelerating, Expanding Universesection "Expansion is Speeding Up, Supernovae Show"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: But in 1998, everything changed when two different teams of astronomers observing far-off supernovae noticed that (at a certain redshift) the stellar explosions were dimmer than expected.

Later work looked for

How the history went; the NASA pages as read in September 2026 carry it.

Claim 7 · checked 24 September 2026 · AI-assisted audit

Claim: the contents of the universe are dominated by things that do not emit, absorb or reflect light.

Kind: What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Modern cosmological models invariably include an electromagnetically close-to-neutral, non-baryonic matter species
Supports
Dark Mattersection "What is Dark Matter?"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: So dark matter doesn't absorb, reflect, or emit any light.
Supports
Planck 2018 results. VI. Cosmological parameterssection 3.2, equation 15
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: a constraint on Ωₘ translates directly into a constraint on the dark-energy density parameter, giving ΩΛ = 0.6847± 0.0073
Notation restored: Subscripts and superscripts restored as the arXiv PDF (1807.06209v4) typesets them, read from glyph positions 2026-09-24; the abstract on arXiv gives H_0 and Ω_m the same way. The text as extracted reads: a constraint on Ωm translates directly into a constraint on the dark-energy density parameter, giving ΩΛ = 0.6847± 0.0073

What this does not establish

Dark energy is not known to be a thing at all; the PDG review uses the name for whatever causes the acceleration, including a change to gravity.

Later work looked for

PDG reviews revised August 2025: nothing that changes it.

Claim 8 · checked 24 September 2026 · AI-assisted audit

What the measurements agree on

Claim: What the measurements agree on

Kind: Framing. Signposting. It asserts nothing a source could check.

Galaxies rotate as though they contain far more mass than we can see

Claim: Galaxies rotate as though they contain far more mass than we can see

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

Supports
Rotational properties of 21 Sc galaxies with a large range of luminosities and radii, from NGC 4605 (R = 4 kpc) to UGC 2885 (R = 122 kpc)abstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: Most rotation curves are rising slowly even at the farthest measured point. Neither high nor low luminosity Sc galaxies have falling rotation curves. Sc galaxies of all luminosities must have significant mass located beyond the optical image.
Supports
Rotational properties of 21 Sc galaxies with a large range of luminosities and radii, from NGC 4605 (R = 4 kpc) to UGC 2885 (R = 122 kpc)section VIII, conclusion 1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: This form for the rotation curves implies that the mass is not centrally condensed, but that significant mass is located at large R. ... The conclusion is inescapable that non-luminous matter exists beyond the optical galaxy.

What this does not establish

"As though" is right: the rotation shows missing mass if Newtonian gravity holds at those scales, which the passage goes on to question.

Later work looked for

PDG dark matter review, revised August 2025: rotation curves remain one of the standard tracers of dark matter; nothing that changes it.

Claim 10 · checked 24 September 2026 · AI-assisted audit

Claim: Vera Rubin and Kent Ford measured how fast gas orbits in spiral galaxies, first in Andromeda and then, with Norbert Thonnard, in twenty-one more, and found that the speed does not fall away towards the edge: in most of them it was still rising slowly at the farthest point measured.

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

Supports
Rotation of the Andromeda Nebula from a Spectroscopic Survey of Emission Regionsabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: Spectra of sixty-seven H n regions from 3 to 24 kpc from the nucleus of M31 have been obtained
The OCR renders H II as "H n".
Supports
Rotation of the Andromeda Nebula from a Spectroscopic Survey of Emission Regionssection V, The Rotation Curve and Mass of M31
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: the fact that the velocities of the outermost points near 7? = 22.6 kpc are not decreasing with increasing R
The OCR renders R as "7?".
Supports
Rotational properties of 21 Sc galaxies with a large range of luminosities and radii, from NGC 4605 (R = 4 kpc) to UGC 2885 (R = 122 kpc)abstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: For 21 Sc galaxies whose properties encompass a wide range of radii, masses, and luminosities, we have obtained major axis spectra extending to the faint outer regions, and have deduced rotation curves.
Supports
Rotational properties of 21 Sc galaxies with a large range of luminosities and radii, from NGC 4605 (R = 4 kpc) to UGC 2885 (R = 122 kpc)abstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: Most rotation curves are rising slowly even at the farthest measured point. Neither high nor low luminosity Sc galaxies have falling rotation curves. Sc galaxies of all luminosities must have significant mass located beyond the optical image.

What this does not establish

The measurements are of glowing gas, not stars. The 1980 sample is 21 Sc galaxies, one type of spiral, and the authors say their conclusions apply only to that type.

Later work looked for

Crossref, 2019 on, "rotation curves spiral galaxies dark matter": alternative explanations are proposed, none that disputes the measurements; the PDG review, revised August 2025, still lists rotation curves among the tracers of dark matter.

Corrected

24 September 2026. Previously: “Vera Rubin and Kent Ford measured how fast stars orbit in spiral galaxies and found that the outer stars move about as fast as the inner ones.” The cited 1970 paper measured emission regions, which are gas, in one galaxy, Andromeda. The result for spiral galaxies as a class is the 1980 paper with Thonnard, now cited, which found most curves still rising at the last point.

Claim 11 · checked 24 September 2026 · AI-assisted audit

Claim: If the visible mass were all the mass, the outer gas would be moving too fast to stay bound.

Kind: What a model says. What a theory or model predicts or describes, which is not the same as what has been observed.
Review: Source checked. The cited passage was read, and it says this.

Supports
Rotational properties of 21 Sc galaxies with a large range of luminosities and radii, from NGC 4605 (R = 4 kpc) to UGC 2885 (R = 122 kpc)section VIII, conclusion 1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: This form for the rotation curves implies that the mass is not centrally condensed, but that significant mass is located at large R. ... The conclusion is inescapable that non-luminous matter exists beyond the optical galaxy.
Supports
Dark matteropening
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: They are rotating with such speed that the gravity generated by their observable matter could not possibly hold them together; they should have torn themselves apart long ago.

What this does not establish

This is what Newtonian gravity says of the visible mass. The next sentence gives the other way out.

Later work looked for

How the inference works; not a finding later work revises.

Corrected

24 September 2026. Previously: “If the visible mass were all the mass, the outer stars would be moving too fast to stay bound.” The measurements are of gas, so the sentence follows them.

Claim 12 · checked 24 September 2026 · AI-assisted audit

Claim: Either there is unseen matter, or gravity behaves differently at those scales.

Kind: What scholars argue. A report of what specialists argue, or where they disagree.
Review: Source checked. The cited passage was read, and it says this.

The first option is Rubin’s reading; the second is Milgrom’s proposal of 1983.

Supports
A modification of the Newtonian dynamics as a possible alternative to the hidden mass hypothesisabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Model
The source reads: I consider the possibility that there is not, in fact, much hidden mass in galaxies and galaxy systems. ... the observational results are reproduced with no need to assume hidden mass in appreciable quantities.
Supports
Rotational properties of 21 Sc galaxies with a large range of luminosities and radii, from NGC 4605 (R = 4 kpc) to UGC 2885 (R = 122 kpc)section VIII, conclusion 1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: This form for the rotation curves implies that the mass is not centrally condensed, but that significant mass is located at large R. ... The conclusion is inescapable that non-luminous matter exists beyond the optical galaxy.
Supports
Modified Newtonian Dynamics (MOND): Observational Phenomenology and Relativistic Extensionsabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: Either (i) there is a vast amount of unseen mass in some novel form - dark matter - or (ii) the data indicate a breakdown of our understanding of dynamics on the relevant scales, or (iii) both.

Other readings

Famaey and McGaugh add a third: both.

Later work looked for

Crossref, 2023 on, "MOND wide binaries Gaia": tests of gravity at low acceleration disagree with each other; the two options stand.

Claim 13 · checked 24 September 2026 · AI-assisted audit

The evidence is not one measurement, it is many

Claim: The evidence is not one measurement, it is many

Kind: What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Assuming the validity of General Relativity, DM is observed to be ubiquitous in gravitation-ally collapsed structures ... the existence of DM is inferred directly using tracers of mass enclosed within a certain radius such as stellar velocity dispersion, rotation curves in axisymmetric systems, the virial theorem, gravitational lensing
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: The picture of structure formation in modern cosmology heavily relies on, and can be considered an independent and exceptionally strong motivation for, DM.

Later work looked for

PDG dark matter review, revised August 2025: the current field-level account.

Claim 14 · checked 24 September 2026 · AI-assisted audit

Claim: Gravitational lensing, the growth of large-scale structure, and the pattern of fluctuations in the cosmic microwave background all independently require substantial non-luminous mass.

Kind: What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Assuming the validity of General Relativity, DM is observed to be ubiquitous in gravitation-ally collapsed structures ... the existence of DM is inferred directly using tracers of mass enclosed within a certain radius such as stellar velocity dispersion, rotation curves in axisymmetric systems, the virial theorem, gravitational lensing
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: The picture of structure formation in modern cosmology heavily relies on, and can be considered an independent and exceptionally strong motivation for, DM.
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Key issues that at present appear highly problematic in the framework of theories of modified gravity without DM include (i) predicting the correct spectrum of density perturbations, (ii) predicting the observed anisotropy power spectrum of the CMB, and (iii) explaining weak lensing and X-ray observations of merging clusters
Supports
Planck 2018 results. VI. Cosmological parameterssection 3.5, equations 22 and 23
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: The matter density is well constrained to be Ωₘh² = 0.1430± 0.0011 (68 %, Planck TT,TE,EE +lowE+lensing). (22) The matter mostly consists of cold dark matter
Notation restored: Subscripts and superscripts restored as the arXiv PDF (1807.06209v4) typesets them, read from glyph positions 2026-09-24; the abstract on arXiv gives H_0 and Ω_m the same way. The text as extracted reads: The matter density is well constrained to be Ωmh2 = 0.1430± 0.0011 (68 %, Planck TT,TE,EE +lowE+lensing). (22) The matter mostly consists of cold dark matter

What this does not establish

Each of these infers mass from gravity, assuming general relativity holds, as the PDG review says. That assumption is what modified gravity questions.

Later work looked for

PDG dark matter review, revised August 2025, and Crossref, 2024 on, "Bullet Cluster JWST lensing": nothing that changes it.

Claim 15 · checked 24 September 2026 · AI-assisted audit

Claim: The Planck satellite’s measurements give roughly 5% ordinary matter, 26% dark matter and 68% dark energy.

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

Planck gives the dark energy share directly, 0.6847. Its baryon and cold dark matter densities, 0.02237 and 0.1200 in units of h², with h = 0.674, give 4.9 and 26.4 per cent.

Supports
Planck 2018 results. VI. Cosmological parameterssection 3.2, equation 15
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: a constraint on Ωₘ translates directly into a constraint on the dark-energy density parameter, giving ΩΛ = 0.6847± 0.0073
Notation restored: Subscripts and superscripts restored as the arXiv PDF (1807.06209v4) typesets them, read from glyph positions 2026-09-24; the abstract on arXiv gives H_0 and Ω_m the same way. The text as extracted reads: a constraint on Ωm translates directly into a constraint on the dark-energy density parameter, giving ΩΛ = 0.6847± 0.0073
Supports
Planck 2018 results. VI. Cosmological parameterssection 3.5, equation 24
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: Despite comprising less than a sixth of the total matter content
Supports
Planck 2018 results. VI. Cosmological parameterssection 3.5, equations 22 and 23
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: The matter density is well constrained to be Ωₘh² = 0.1430 ± 0.0011 (68 %, Planck TT,TE,EE +lowE+lensing). (22) The matter mostly consists of cold dark matter
Notation restored: Subscript and superscript restored from the arXiv PDF (v4) rendered as a page image at equation 22, read 2026-09-24. The text as extracted reads: The matter density is well constrained to be Ωmh2 = 0.1430± 0.0011 (68 %, Planck TT,TE,EE +lowE+lensing). (22) The matter mostly consists of cold dark matter
Supports
Planck 2018 results. VI. Cosmological parametersabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: Hubble constant H₀ = (67.4±0.5) km s⁻¹ Mpc⁻¹; matter density parameter Ωₘ = 0.315±0.007
Notation restored: Subscripts, superscripts and a lost space restored from the arXiv PDF (v4) rendered as a page image at the abstract, read 2026-09-24. The text as extracted reads: Hubble constant H0 = (67.4±0.5) km s−1Mpc−1; matter density parameterΩm = 0.315±0.007
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: the DM accounts for 26.4% of the critical density in the universe, or 84.4% of the total matter density.

What this does not establish

These are the parameters of the standard cosmological model fitted to Planck’s data, not direct measurements of each component.

Later work looked for

PDG dark matter review, revised August 2025, gives dark matter as 26.4 per cent of the critical density for the benchmark model; nothing later that moves the rounded figures.

Corrected

24 September 2026. Previously: “The Planck satellite’s measurements give roughly 5% ordinary matter, 27% dark matter and 68% dark energy.” 27 per cent is the figure from Planck’s 2013 results. The 2018 parameters the page cites give 26.4 per cent, which the PDG review also gives.

Claim 16 · checked 24 September 2026 · AI-assisted audit

Claim: In the Bullet Cluster, two galaxy clusters collided.

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

Supports
A Direct Empirical Proof of the Existence of Dark Matterabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: Due to the collision of two clusters, the dissipationless stellar component and the fluid-like X-ray emitting plasma are spatially segregated.

Later work looked for

Crossref, 2024 on, "Bullet Cluster JWST lensing": JWST lensing maps (2025) redraw the mass in more detail; nothing that reverses it.

Corrected

24 September 2026. Previously: “In the Bullet Cluster, two colliding galaxy clusters separated into a visible hot gas component and a gravitationally dominant component that passed straight through.” Split and made exact: what passed through were the galaxies, and the paper shows the mass following them. The gas is visible only in X-rays.

Claim 17 · checked 24 September 2026 · AI-assisted audit

Claim: Their hot gas, which glows in X-rays and holds most of their ordinary matter, was slowed by the collision; their galaxies passed straight through.

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

Supports
A Direct Empirical Proof of the Existence of Dark Matterabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: we create gravitational lensing maps which show that the gravitational potential does not trace the plasma distribution, the dominant baryonic mass component, but rather approximately traces the distribution of galaxies.
Supports
A Direct Empirical Proof of the Existence of Dark Mattersection 1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: Two galaxy concentrations that correspond to the main cluster and the smaller subcluster have moved ahead of their respective plasma clouds that have been slowed by ram pressure.

Later work looked for

Crossref, 2024 on, "Bullet Cluster JWST lensing": nothing that changes it.

Claim 18 · checked 24 September 2026 · AI-assisted audit

Claim: Gravitational lensing shows the mass travelling with the galaxies, not with the gas.

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

Supports
A Direct Empirical Proof of the Existence of Dark Matterabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: we create gravitational lensing maps which show that the gravitational potential does not trace the plasma distribution, the dominant baryonic mass component, but rather approximately traces the distribution of galaxies.

Later work looked for

Crossref, 2024 on, "Bullet Cluster JWST lensing": the 2025 JWST analysis maps the same separation; nothing that changes it.

Claim 19 · checked 24 September 2026 · AI-assisted audit

Claim: The mass and most of the ordinary matter are in demonstrably different places.

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

Supports
A Direct Empirical Proof of the Existence of Dark Matterabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: An 8-sigma significance spatial offset of the center of the total mass from the center of the baryonic mass peaks cannot be explained with an alteration of the gravitational force law, and thus proves that the majority of the matter in the system is unseen.
Supports
A Direct Empirical Proof of the Existence of Dark Matterabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: we create gravitational lensing maps which show that the gravitational potential does not trace the plasma distribution, the dominant baryonic mass component, but rather approximately traces the distribution of galaxies.
Qualifies
A Detailed MOND Modelling of the Bullet Clusterabstract
Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Astronomical observation · Model
The source reads: I show that the surface density that QUMOND predicts will be inferred under GR from the gravitational potential of the “Bullet Cluster,” qualitatively matches the spatial distribution of what GR inferences of lensing observations return.

What this does not establish

One system. Clowe and colleagues conclude that a change to the law of gravity cannot explain the offset. A 2026 MOND model of the same cluster argues that it can, while still needing 1.6 times more mass than the ordinary matter seen, as MOND does in other clusters (claim 43).

Later work looked for

Crossref, 2024 on, "Bullet Cluster JWST lensing" and "Bullet Cluster MOND": the separation stands; a 2026 MOND model argues it reproduces the lensing map; recorded here.

Corrected

24 September 2026. Previously: “The mass and the light are in demonstrably different places.” The mass sits with the galaxies, which are light. What it is separated from is the X-ray gas, the largest part of the ordinary matter.

Claim 20 · checked 24 September 2026 · AI-assisted audit

Claim: The energy content of the universe, from Planck 2018

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

The three percentages below are computed from Planck’s 2018 parameters, as claim 16 shows.

Supports
Planck 2018 results. VI. Cosmological parameterssection 3.2, equation 15
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: a constraint on Ωₘ translates directly into a constraint on the dark-energy density parameter, giving ΩΛ = 0.6847± 0.0073
Notation restored: Subscripts and superscripts restored as the arXiv PDF (1807.06209v4) typesets them, read from glyph positions 2026-09-24; the abstract on arXiv gives H_0 and Ω_m the same way. The text as extracted reads: a constraint on Ωm translates directly into a constraint on the dark-energy density parameter, giving ΩΛ = 0.6847± 0.0073
Supports
Planck 2018 results. VI. Cosmological parameterssection 3.5, equations 22 and 23
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: The matter density is well constrained to be Ωₘh² = 0.1430± 0.0011 (68 %, Planck TT,TE,EE +lowE+lensing). (22) The matter mostly consists of cold dark matter
Notation restored: Subscripts and superscripts restored as the arXiv PDF (1807.06209v4) typesets them, read from glyph positions 2026-09-24; the abstract on arXiv gives H_0 and Ω_m the same way. The text as extracted reads: The matter density is well constrained to be Ωmh2 = 0.1430± 0.0011 (68 %, Planck TT,TE,EE +lowE+lensing). (22) The matter mostly consists of cold dark matter

Later work looked for

PDG dark matter review, revised August 2025: the same budget.

Claim 21 · checked 24 September 2026 · AI-assisted audit

Claim: 5%

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

Supports
Planck 2018 results. VI. Cosmological parameterssection 3.5, equation 24
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: Despite comprising less than a sixth of the total matter content
Supports
Planck 2018 results. VI. Cosmological parametersabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: Hubble constant H₀ = (67.4±0.5) km s⁻¹ Mpc⁻¹; matter density parameter Ωₘ = 0.315±0.007
Notation restored: Subscripts and superscripts restored as the arXiv PDF (1807.06209v4) typesets them, read from glyph positions 2026-09-24; the abstract on arXiv gives H_0 and Ω_m the same way. The text as extracted reads: Hubble constant H0 = (67.4±0.5) km s−1Mpc−1; matter density parameterΩm = 0.315±0.007

Later work looked for

PDG dark matter review, revised August 2025: nothing that changes it.

Claim 22 · checked 24 September 2026 · AI-assisted audit

Claim: Ordinary matter

Kind: Framing. Signposting. It asserts nothing a source could check.

Claim: Every atom, star, planet and particle in the Standard Model.

Kind: About a word. What a word in the original language means, or how it is translated.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Mattersection "What is Dark Matter?"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: From stars and galaxies to the shoes on your feet, ordinary matter makes up everything we can see in the universe
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: The nature of only a small fraction, between at least 0.5% (given neutrino os-cillations) and at most 1.6% (from combined cosmological constraints), of the non-baryonic matter content of the universe is known: the three Standard Model neutrinos

What this does not establish

Strictly the 5 per cent is the atoms; the Standard Model’s neutrinos add a fraction of a per cent on top.

Claim 24 · checked 24 September 2026 · AI-assisted audit

Claim: 26%

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

Supports
Planck 2018 results. VI. Cosmological parameterssection 3.5, equations 22 and 23
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: The matter density is well constrained to be Ωₘh² = 0.1430 ± 0.0011 (68 %, Planck TT,TE,EE +lowE+lensing). (22) The matter mostly consists of cold dark matter
Notation restored: Subscript and superscript restored from the arXiv PDF (v4) rendered as a page image at equation 22, read 2026-09-24. The text as extracted reads: The matter density is well constrained to be Ωmh2 = 0.1430± 0.0011 (68 %, Planck TT,TE,EE +lowE+lensing). (22) The matter mostly consists of cold dark matter
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: the DM accounts for 26.4% of the critical density in the universe, or 84.4% of the total matter density.

Later work looked for

PDG dark matter review, revised August 2025: 26.4 per cent.

Corrected

24 September 2026. Previously: “27%” Planck 2018 and the PDG review give 26.4 per cent; 27 was Planck’s 2013 figure.

Claim 25 · checked 24 September 2026 · AI-assisted audit

Claim: Dark matter

Kind: Framing. Signposting. It asserts nothing a source could check.

Claim: Measured by its gravity.

Kind: What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Assuming the validity of General Relativity, DM is observed to be ubiquitous in gravitation-ally collapsed structures ... the existence of DM is inferred directly using tracers of mass enclosed within a certain radius such as stellar velocity dispersion, rotation curves in axisymmetric systems, the virial theorem, gravitational lensing

Later work looked for

PDG dark matter review, revised August 2025: nothing that changes it.

Claim 27 · checked 24 September 2026 · AI-assisted audit

Claim: Never confirmed in a detector.

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.6.3
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: It is the only experiment in the field that reported an annually modulated event rate with a statistical significance of 12.9σC.L. (20 annual cycles)
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.6.3
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: An analysis of 6 years of data with an exposure of 625.75kgy is incompatible with the DAMA/LI-BRA modulation signal at 4σC.L. ... A new analysis disfavors the DAMA/LIBRA signal as originating from WIMP interactions, fully excluding the 3σallowed regions
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.6.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: No signal for DM has been observed in the LHC experiments so far. Instead, limits are set on masses, couplings, and cross-sections.
Supports
Dark Mattersection "Leading Dark Matter Candidates"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: For context, scientists have been searching for these candidates but have not yet found evidence which would confirm any candidate.

What this does not establish

One experiment, DAMA/LIBRA, reports a signal, which is why the note says confirmed; two others testing it with the same kind of crystal do not see it (claim 55).

Later work looked for

PDG dark matter review, revised August 2025, including the LZ and XENONnT results of 2025: no confirmed signal.

Corrected

24 September 2026. Previously: “Never detected directly.” "Direct detection" is ambiguous here: the Bullet Cluster paper this page cites calls its lensing map a direct detection of dark matter. What has never happened is a detector recording a dark matter particle.

24 September 2026. Previously: “Never caught in a detector.” A universal the evidence does not carry: DAMA/LIBRA reports an annually modulated signal it reads as dark matter, which others fail to reproduce. What no source reports is a confirmed detection.

Claim 28 · checked 24 September 2026 · AI-assisted audit

Claim: 68%

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

Supports
Planck 2018 results. VI. Cosmological parameterssection 3.2, equation 15
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: a constraint on Ωₘ translates directly into a constraint on the dark-energy density parameter, giving ΩΛ = 0.6847± 0.0073
Notation restored: Subscripts and superscripts restored as the arXiv PDF (1807.06209v4) typesets them, read from glyph positions 2026-09-24; the abstract on arXiv gives H_0 and Ω_m the same way. The text as extracted reads: a constraint on Ωm translates directly into a constraint on the dark-energy density parameter, giving ΩΛ = 0.6847± 0.0073

Later work looked for

PDG dark energy review, revised August 2025: nothing that moves the rounded figure.

Claim 29 · checked 24 September 2026 · AI-assisted audit

Claim: Dark energy

Kind: Framing. Signposting. It asserts nothing a source could check.

Claim: Named for the acceleration it describes, not for anything known about it.

Kind: About a word. What a word in the original language means, or how it is translated.
Review: Source checked. The cited passage was read, and it says this.

Supports
What is Dark Energy? Inside Our Accelerating, Expanding Universesection "What Exactly is Dark Energy?"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: Right now, dark energy is just the name that astronomers gave to the mysterious "something" that is causing the universe to expand at an accelerated rate.
Supports
Dark Energy (Review of Particle Physics, chapter 28)section 28.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: The title of this article follows the common but inexact usage of “dark energy” as a catch-all term for the origin of cosmic acceleration, regardless of whether it arises from a new form of energy or a modification of GR.

Claim 31 · checked 24 September 2026 · AI-assisted audit

The expansion of the universe is accelerating

Claim: The expansion of the universe is accelerating

Kind: What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Energy (Review of Particle Physics, chapter 28)section 28.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Today, the accelerating Universe is well established by multiple lines of independent evidence from a tight web of precise cosmological measurements.

What this does not establish

That acceleration needs a new kind of energy assumes general relativity holds on cosmological scales, as the PDG review notes.

Later work looked for

PDG dark energy review, revised August 2025: the acceleration is well established; whether its cause changes over time is what DESI questions (claim 68).

Claim 32 · checked 24 September 2026 · AI-assisted audit

Claim: Observations of distant supernovae in the late 1990s showed that cosmic expansion is speeding up rather than slowing under gravity.

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

Supports
Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constantabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: The distances of the high-redshift SNe Ia are, on average, 10 % to 15% farther than expected in a low mass density (Ω M = 0 . 2) Universe without a cosmological constant.
Supports
Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constantabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: unanimously favor eternally expanding models with positive cosmological constant (i.e ., Ω Λ > 0) and a current acceleration of the expansion
Supports
Dark Energy (Review of Particle Physics, chapter 28)section 28.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: In the late 1990s, supernova surveys by two independent teams provided direct evidence for accelerating cosmic expansion
Supports
What is Dark Energy? Inside Our Accelerating, Expanding Universesection "Expansion is Speeding Up, Supernovae Show"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: But in 1998, everything changed when two different teams of astronomers observing far-off supernovae noticed that (at a certain redshift) the stellar explosions were dimmer than expected.

What this does not establish

The supernovae show it with 16 and 42 objects in the two original studies; the case now rests on many methods, as the PDG review says.

Later work looked for

PDG dark energy review, revised August 2025: the acceleration is well established by many methods; Crossref, 2020 on, "type Ia supernova cosmology accelerating expansion": work on supernova systematics, nothing that reverses it. See claim 68 for whether it is constant.

Claim 33 · checked 24 September 2026 · AI-assisted audit

Claim: The cause is labelled dark energy.

Kind: About a word. What a word in the original language means, or how it is translated.
Review: Source checked. The cited passage was read, and it says this.

Supports
What is Dark Energy? Inside Our Accelerating, Expanding Universesection "What Exactly is Dark Energy?"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: Right now, dark energy is just the name that astronomers gave to the mysterious "something" that is causing the universe to expand at an accelerated rate.
Supports
Dark Energy (Review of Particle Physics, chapter 28)section 28.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: The title of this article follows the common but inexact usage of “dark energy” as a catch-all term for the origin of cosmic acceleration, regardless of whether it arises from a new form of energy or a modification of GR.

Claim 34 · checked 24 September 2026 · AI-assisted audit

Claim: Naming it did not explain it.

Kind: This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review: A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

NASA’s own answer to what dark energy is: “We don't know.”

Supports
What is Dark Energy? Inside Our Accelerating, Expanding Universeopening
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: But what exactly is dark energy? The short answer is: We don't know.

Claim 35 · checked 24 September 2026 · AI-assisted audit

A particle, or something else

Claim: A particle, or something else

Kind: Framing. Signposting. It asserts nothing a source could check.

Whether dark matter is a particle

Claim: Whether dark matter is a particle

Kind: Framing. Signposting. It asserts nothing a source could check.

Claim: The leading candidate class (weakly interacting massive particles) has been searched for with increasingly sensitive underground detectors for decades, with no confirmed detection.

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.5
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: WIMPs: The WIMP paradigm has been a preferred framework
Supports
Dark Mattersection "Leading Dark Matter Candidates"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: WIMPs, or Weakly Interacting Massive Particles, represent a favored class of dark matter candidates.
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.6.3
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Several large DM experiments using high-purity NaI(Tl) crystals are acquiring data in various underground laboratories.
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.6.3
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: At present the best constraints on DM-nucleus interactions come from multi-tonne experiments using LXe: the LZ experiment at SURF, PandaX-4T at CJPL and XENONnT at LNGS.
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.6.3
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: It is the only experiment in the field that reported an annually modulated event rate with a statistical significance of 12.9σC.L. (20 annual cycles)
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.6.3
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: An analysis of 6 years of data with an exposure of 625.75kgy is incompatible with the DAMA/LI-BRA modulation signal at 4σC.L. ... A new analysis disfavors the DAMA/LIBRA signal as originating from WIMP interactions, fully excluding the 3σallowed regions
Supports
Dark Mattersection "Leading Dark Matter Candidates"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: For context, scientists have been searching for these candidates but have not yet found evidence which would confirm any candidate.

What this does not establish

DAMA/LIBRA has reported a yearly signal over 20 cycles; experiments testing it do not confirm it. "Leading" is the NASA page’s "favored class" and the PDG review’s "preferred framework".

Later work looked for

PDG dark matter review, revised August 2025, with LZ and XENONnT 2025 limits; Crossref, 2025 on, "LZ dark matter WIMP search results": no detection reported.

Claim 38 · checked 24 September 2026 · AI-assisted audit

Claim: Each null result narrows the allowed parameter space without ruling out the idea.

Kind: What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.6.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: No signal for DM has been observed in the LHC experiments so far. Instead, limits are set on masses, couplings, and cross-sections.
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.6.3
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: These will increase the sensitivity to various DM candidates by 1-2 orders of magnitude, with the ultimate goal of exploring the parameter space until the backgrounds from astrophysical neutrinos will start dominating the event rates.

What this does not establish

The PDG review sets a floor: below a certain rate, neutrinos from space swamp any signal, so direct searches cannot rule WIMPs out entirely.

Later work looked for

PDG dark matter review, revised August 2025: nothing that changes it.

Claim 39 · checked 24 September 2026 · AI-assisted audit

Claim: Axions, sterile neutrinos and primordial black holes remain alternatives, the last two now tightly constrained, and each is being searched for with different instruments.

Kind: What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.5
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: axions in connection with frameworks that address the strongCP problem ... sterile neutrinos in connection with the problem of neutrino masses and mixing
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.5, axions
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: The experimental portfolio includes the broadband axion search
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.5, sterile neutrinos
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: have placed stringent constraints on the sterile neutrino interpretation of the 3.5 keV feature ... structure formation constraints now robustly disfavor most of the Dodelson-Widrow production mechanism for sterile neutrino dark matter [103], although resonant production in the presence of a lepton asymmetry remains viable
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.7, primordial black holes
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Overall, the parameter space for PBHs as a dominant DM component remains tightly con-strained but not conclusively excluded, motivating ongoing efforts across multiple observational frontiers.
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.7, primordial black holes
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: A robust window for PBHs to constitute all of the dark matter persists roughly in the mass range

What this does not establish

For sterile neutrinos, one production route survives; for primordial black holes, one range of masses, from asteroid to lunar.

Later work looked for

PDG dark matter review, revised August 2025: XRISM and NuSTAR constrain sterile neutrinos, and primordial black holes keep one mass window; recorded on the page.

Corrected

24 September 2026. Previously: “Axions, sterile neutrinos and primordial black holes remain live alternatives, and each is being searched for with different instruments.” The PDG review, revised 2025, describes sterile-neutrino dark matter as mostly disfavoured apart from one production route, and primordial black holes as tightly constrained but not excluded.

Claim 40 · checked 24 September 2026 · AI-assisted audit

Whether gravity itself needs modifying

Claim: Whether gravity itself needs modifying

Kind: Framing. Signposting. It asserts nothing a source could check.

Claim: Modified Newtonian dynamics and its relativistic descendants reproduce galaxy rotation curves impressively well with no dark matter at all.

Kind: What scholars argue. A report of what specialists argue, or where they disagree.
Review: Source checked. The cited passage was read, and it says this.

"Impressively well" is the assessment of MOND’s own reviewers, who call the fits uncanny; the PDG review grants that modified gravity mimics dark matter on a limited range of scales.

Supports
A modification of the Newtonian dynamics as a possible alternative to the hidden mass hypothesisabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Model
The source reads: I consider the possibility that there is not, in fact, much hidden mass in galaxies and galaxy systems. ... the observational results are reproduced with no need to assume hidden mass in appreciable quantities.
Supports
Modified Newtonian Dynamics (MOND): Observational Phenomenology and Relativistic Extensionssection 6.5.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: it also predicts the shape ... amplitude of galactic rotation curves at all radii with uncanny precision, and this for all disk galaxy Hubble types
Supports
Modified Newtonian Dynamics (MOND): Observational Phenomenology and Relativistic Extensionsabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: summarize the various theoretical attempts (TeVeS, GEA, BIMOND, and others) made to effectively embed this modification of Newtonian dynamics within a relativistic theory of gravity
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Usually such theories mimic the effects otherwise attributed to DM on a limited range of scales, but fail globally, and especially at the largest scales.

Later work looked for

Crossref, 2023 on, "MOND wide binaries Gaia": wide-binary tests are split, some reporting a preference for general relativity and some for MOND; rotation-curve fits are not in dispute.

Claim 42 · checked 24 September 2026 · AI-assisted audit

Claim: They struggle with galaxy clusters, where even their proponents find mass still missing.

Kind: What scholars argue. A report of what specialists argue, or where they disagree.
Review: Source checked. The cited passage was read, and it says this.

In clusters, MOND needs more mass than can be seen: roughly twice as much in Famaey and McGaugh’s review, 1.6 times in a 2026 MOND model of the Bullet Cluster.

Supports
Modified Newtonian Dynamics (MOND): Observational Phenomenology and Relativistic Extensionsfigure 39 caption
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: This is the residual missing baryon problem in MOND
Context
A Detailed MOND Modelling of the Bullet Clusterabstract
Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Astronomical observation · Model
The source reads: As is common under MOND modeling of galaxy clusters, a mass deficit on the baryon content is obtained, in this case by a factor of 1.6.
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Key issues that at present appear highly problematic in the framework of theories of modified gravity without DM include (i) predicting the correct spectrum of density perturbations, (ii) predicting the observed anisotropy power spectrum of the CMB, and (iii) explaining weak lensing and X-ray observations of merging clusters

What this does not establish

The 2026 model was read as an abstract only.

Later work looked for

Crossref, 2024 on, "Bullet Cluster MOND": a 2026 MOND model of the Bullet Cluster still finds a mass deficit, a factor of 1.6; the page’s wording holds.

Corrected

24 September 2026. Previously: “They struggle with galaxy clusters and with the cosmic microwave background.” Split, so that each difficulty is stated with its source; the cluster problem is acknowledged in the proponents’ own review.

Claim 43 · checked 24 September 2026 · AI-assisted audit

Claim: Most versions also fail on the cosmic microwave background, though the authors of one relativistic theory, published in 2021, report that theirs fits it.

Kind: What scholars argue. A report of what specialists argue, or where they disagree.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Key issues that at present appear highly problematic in the framework of theories of modified gravity without DM include (i) predicting the correct spectrum of density perturbations, (ii) predicting the observed anisotropy power spectrum of the CMB, and (iii) explaining weak lensing and X-ray observations of merging clusters
Supports
Modified Newtonian Dynamics (MOND): Observational Phenomenology and Relativistic Extensionssection 9.2
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Review of the field
The source reads: second and third peaks falsifies the simple no-CDM anzatz
Supports
New Relativistic Theory for Modified Newtonian Dynamicsabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Model
The source reads: We propose a relativistic gravitational theory leading to modified Newtonian dynamics ... demonstrate its agreement with the observed cosmic microwave background and matter power spectra on linear cosmological scales.
Supports
New Relativistic Theory for Modified Newtonian Dynamicsintroduction
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Model
The source reads: In cases where the CMB and matter power spectra (MPS) have been computed, no theory has been shown to fit all of the cosmological data while preserving MOND phenomenology in galaxies
Supports
New Relativistic Theory for Modified Newtonian Dynamicsconclusions
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Model
The source reads: We have shown how the cosmological regime of this theory reproduces the CMB and MPS power spectra on linear scales

What this does not establish

Its authors report agreement with the microwave background and matter power spectra on large, linear scales, not with galaxy clusters, and call the link between those scales and galaxies an open problem.

Later work looked for

Crossref, 2021 on, "relativistic MOND cosmic microwave background": no further claim of a fit found; the 2021 theory is recorded on the page.

Corrected

24 September 2026. Previously: “They struggle with galaxy clusters and with the cosmic microwave background.” A 2021 relativistic theory reports agreement with the microwave background, so the blanket statement is narrowed and the exception attributed.

Claim 44 · checked 24 September 2026 · AI-assisted audit

Claim: The mainstream view is that dark matter is real;

Kind: What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Modern cosmological models invariably include an electromagnetically close-to-neutral, non-baryonic matter species

Later work looked for

PDG dark matter review, revised August 2025: nothing that changes it.

Claim 45 · checked 24 September 2026 · AI-assisted audit

Claim: the alternative is not dead.

Kind: This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review: A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Follows from claims 42 and 44: modified gravity keeps its rotation-curve successes and one recent relativistic version claims the microwave background.

Claim 46 · checked 24 September 2026 · AI-assisted audit

How fast the universe is expanding

Claim: How fast the universe is expanding

Kind: Framing. Signposting. It asserts nothing a source could check.

Claim: Measurements of the expansion rate from the early universe and from nearby distance indicators disagree by more than their stated uncertainties: by five standard deviations, according to the SH0ES team, which has tested its own analysis in nearly seventy variants.

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

Supports
A Comprehensive Measurement of the Local Value of the Hubble Constant with 1 km/s/Mpc Uncertaintyabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: We find a 5σ difference with the prediction of H0 from Planck CMB observations under ΛCDM, with no indication that the discrepancy arises from measurement uncertainties or analysis variations considered to date.
Supports
A Comprehensive Measurement of the Local Value of the Hubble Constant with 1 km/s/Mpc Uncertaintyabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: We present results for a comprehensive set of nearly 70 analysis variants to explore the sensitivity of H₀
Notation restored: Subscript and superscripts restored as the arXiv version of the paper (2112.04510) typesets them: the 0 after H is lowered and set small, the −1 after s and after Mpc raised, read from glyph positions 2026-09-24. The text as extracted reads: We present results for a comprehensive set of nearly 70 analysis variants to explore the sensitivity of H 0
Supports
A Comprehensive Measurement of the Local Value of the Hubble Constant with 1 km/s/Mpc Uncertaintyabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: Our baseline result from the Cepheid–SN Ia sample is H₀ = 73.04 ± 1.04 km s⁻¹ Mpc⁻¹, which includes systematic uncertainties
Notation restored: Subscript and superscripts restored as the arXiv version of the paper (2112.04510) typesets them: the 0 after H is lowered and set small, the −1 after s and after Mpc raised, read from glyph positions 2026-09-24. The text as extracted reads: Our baseline result from the Cepheid–SN Ia sample is H 0 = 73.04± 1.04 km s−1 Mpc−1, which includes systematic uncertainties
Supports
Planck 2018 results. VI. Cosmological parametersabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: Hubble constant H₀ = (67.4±0.5) km s⁻¹ Mpc⁻¹; matter density parameter Ωₘ = 0.315±0.007
Notation restored: Subscripts and superscripts restored as the arXiv PDF (1807.06209v4) typesets them, read from glyph positions 2026-09-24; the abstract on arXiv gives H_0 and Ω_m the same way. The text as extracted reads: Hubble constant H0 = (67.4±0.5) km s−1Mpc−1; matter density parameterΩm = 0.315±0.007

What this does not establish

Planck gives 67.4 ± 0.5 and SH0ES 73.04 ± 1.04 kilometres per second per megaparsec. The five-sigma figure is the SH0ES team’s own. The fuller account is in the exploration devoted to it.

Later work looked for

Crossref, 2022 on, "Hubble tension" and "Chicago-Carnegie Hubble Program JWST": SH0ES still finds the gap; the CCHP team finds a lower local value; the page now reports both.

Corrected

24 September 2026. Previously: “Measurements of the expansion rate from the early universe and from nearby distance indicators disagree by more than their stated uncertainties. The discrepancy has survived years of cross-checking.” The significance and the cross-checking are one team’s, and a rival team disagrees about the local value, so both are attributed.

Claim 48 · checked 24 September 2026 · AI-assisted audit

Claim: A rival team calibrating the nearby route with red giant stars gets a value between the two and sees no need for new physics.

Kind: What scholars argue. A report of what specialists argue, or where they disagree.
Review: Source checked. The cited passage was read, and it says this.

Supports
Status Report on the Chicago-Carnegie Hubble Program (CCHP): Measurement of the Hubble Constant Using the Hubble and James Webb Space Telescopesabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: Our current best (highest precision) estimate is H₀ = 70.39 ± 1.22 (stat) ± 1.33 (sys) ± 0.70 (σ_SN), based on the TRGB method alone ... Our results are consistent with the current standard ΛCDM model, ... without the need for the inclusion of additional new physics.
Notation restored: Subscripts restored from the arXiv PDF (v3) rendered as a page image, where they read H₀ and σ with SN below, read 2026-09-24. The text as extracted reads: Our current best (highest precision) estimate is H0 = 70.39 ± 1.22 (stat) ± 1.33 (sys) ± 0.70 (σSN ), based on the TRGB method alone ... Our results are consistent with the current standard ΛCDM model, ... without the need for the inclusion of additional new physics.

What this does not establish

CCHP’s red-giant value is 70.39, between Planck’s 67.4 and SH0ES’s 73.04.

Other readings

The SH0ES team finds red giants agree with its Cepheids and puts the difference down to sample selection.

Later work looked for

Crossref, 2024 on, "Chicago-Carnegie Hubble Program JWST": this is the latest CCHP result; SH0ES (Riess and others 2024) attributes the lower value to which supernovae each sample includes.

Corrected

24 September 2026. Previously: “” Added: the local measurement is itself contested, and the rival result was missing.

Claim 49 · checked 24 September 2026 · AI-assisted audit

Claim: The gap may be a systematic error nobody has found, or a sign that the standard cosmological model is incomplete.

Kind: Open question. Something the page says is not known.
Review: Presented as open. The page says this is unresolved, and the review found that it is.

Both teams’ papers leave the cause open.

Supports
A Comprehensive Measurement of the Local Value of the Hubble Constant with 1 km/s/Mpc Uncertaintyabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: The source of this now long-standing discrepancy between direct and cosmological routes to determining H₀ remains unknown.
Notation restored: Subscript and superscripts restored as the arXiv version of the paper (2112.04510) typesets them: the 0 after H is lowered and set small, the −1 after s and after Mpc raised, read from glyph positions 2026-09-24. The text as extracted reads: The source of this now long-standing discrepancy between direct and cosmological routes to determining H 0 remains unknown.

Corrected

24 September 2026. Previously: “It may be a systematic error nobody has found, or it may be a sign that the standard cosmological model is incomplete.” Reworded to follow the corrected sentences before it.

Claim 50 · checked 24 September 2026 · AI-assisted audit

Two blanks, both enormous

Claim: Two blanks, both enormous

Kind: Framing. Signposting. It asserts nothing a source could check.

Claim: Everything humanity has ever seen, in every direction, with every instrument ever built, is about five percent of what is there.

Kind: This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review: A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

A restatement of the 5 per cent figure for ordinary matter.

What this does not establish

Not everything ordinary has been seen, and the 5 per cent is a share of energy content within the standard model, not a count of things.

Claim 52 · checked 24 September 2026 · AI-assisted audit

What dark matter is

Claim: What dark matter is

Kind: Framing. Signposting. It asserts nothing a source could check.

Claim: No particle in the Standard Model can account for it.

Kind: What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: The nature of only a small fraction, between at least 0.5% (given neutrino os-cillations) and at most 1.6% (from combined cosmological constraints), of the non-baryonic matter content of the universe is known: the three Standard Model neutrinos
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: The fundamental makeup of the large majority of the DM is, as of yet, unknown.
Supports
Dark matteropening
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: Dark matter candidates arise frequently in theories that suggest physics beyond the Standard Model

What this does not establish

Standard Model neutrinos are dark matter of a kind, but between 0.5 and 1.6 per cent of it by the PDG review’s figures.

Later work looked for

PDG dark matter review, revised August 2025: nothing that changes it.

Claim 54 · checked 24 September 2026 · AI-assisted audit

Claim: No detector has recorded it beyond dispute: one experiment reports a seasonal signal, and two others built from the same kind of crystal to test it do not see it.

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

The signal is DAMA/LIBRA’s; ANAIS finds its data incompatible with it and COSINE-100 disfavours it.

Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.6.3, room temperature scintillators
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Several large DM experiments using high-purity NaI(Tl) crystals are acquiring data in various underground laboratories. Of these, DAMA/LIBRA ... It is the only experiment in the field that reported an annually modulated event rate with a statistical significance of 12.9σC.L. (20 annual cycles)
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.6.3, room temperature scintillators, ANAIS and COSINE-100
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: The ANAIS experiment ... operates 112.5kg of NaI(Tl) scintillators ... is incompatible with the DAMA/LI-BRA modulation signal at 4σC.L. ... The COSINE-100 experiment ... operated 106kg of NaI(Tl) crystals ... A new analysis disfavors the DAMA/LIBRA signal as originating from WIMP interactions
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.6.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: No signal for DM has been observed in the LHC experiments so far. Instead, limits are set on masses, couplings, and cross-sections.

Later work looked for

PDG dark matter review, revised August 2025, which reports the ANAIS and COSINE-100 analyses; nothing later found.

Corrected

24 September 2026. Previously: “No detector has recorded it.” DAMA/LIBRA reports a signal; the flat denial was not accurate, and the refutation is itself a result.

Claim 55 · checked 24 September 2026 · AI-assisted audit

Claim: Its existence is inferred entirely from its gravitational effects, which are measured precisely and consistently across many independent methods.

Kind: What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Assuming the validity of General Relativity, DM is observed to be ubiquitous in gravitation-ally collapsed structures ... the existence of DM is inferred directly using tracers of mass enclosed within a certain radius such as stellar velocity dispersion, rotation curves in axisymmetric systems, the virial theorem, gravitational lensing
Supports
Planck 2018 results. VI. Cosmological parameterssection 3.5, equations 22 and 23
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: The matter density is well constrained to be Ωₘh² = 0.1430± 0.0011 (68 %, Planck TT,TE,EE +lowE+lensing). (22) The matter mostly consists of cold dark matter
Notation restored: Subscripts and superscripts restored as the arXiv PDF (1807.06209v4) typesets them, read from glyph positions 2026-09-24; the abstract on arXiv gives H_0 and Ω_m the same way. The text as extracted reads: The matter density is well constrained to be Ωmh2 = 0.1430± 0.0011 (68 %, Planck TT,TE,EE +lowE+lensing). (22) The matter mostly consists of cold dark matter

What this does not establish

The inference assumes general relativity, as the PDG review states.

Later work looked for

PDG dark matter review, revised August 2025: nothing that changes it.

Claim 56 · checked 24 September 2026 · AI-assisted audit

What dark energy is

Claim: What dark energy is

Kind: Framing. Signposting. It asserts nothing a source could check.

Claim: The simplest description is a constant energy density of empty space.

Kind: What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Energy (Review of Particle Physics, chapter 28)section 28.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: one can view the “cosmological constant”Λ as representing a constant energy density of the vacuum
Supports
Dark Energy (Review of Particle Physics, chapter 28)section 28.2.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: A cosmological constant is the mathematically simplest, and perhaps the physically simplest, theoretical explanation for the accelerating Universe. The problem is explaining its unnaturally small magnitude

Later work looked for

PDG dark energy review, revised August 2025: still the simplest; DESI’s hint of change is on the page (claim 68).

Claim 58 · checked 24 September 2026 · AI-assisted audit

Claim: Calculating that value from quantum field theory gives an answer wrong by many tens of orders of magnitude.

Kind: What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review: Source checked. The cited passage was read, and it says this.

Weinberg’s cancellations run from about 41 decimal places, counting only the strong force, to 118, counting everything up to the Planck scale.

Supports
The cosmological constant problemsection III
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field
The source reads: so the two terms here must cancel to better than 118 decimal places. Even if we only worry about zero-point energies in quantum chromo dynamics
Supports
The cosmological constant problemsection III
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field
The source reads: requiring I,/SmG to cancel this term to about 41 decimal places
OCR of "λ/8πG".
Supports
Dark Energy (Review of Particle Physics, chapter 28)section 28.2.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: A cosmological constant is the mathematically simplest, and perhaps the physically simplest, theoretical explanation for the accelerating Universe. The problem is explaining its unnaturally small magnitude
Supports
What is Dark Energy? Inside Our Accelerating, Expanding Universesection "Vacuum Energy"
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026
The source reads: This means that the amount of vacuum energy in the cosmos must be much smaller than it is in these predictions. However, this discrepancy has yet to be solved and has even earned the moniker "the cosmological constant problem."

Later work looked for

PDG dark energy review, revised August 2025: the problem stands.

Claim 59 · checked 24 September 2026 · AI-assisted audit

Claim: Steven Weinberg’s 1989 review of the problem put the gap at some 120.

Kind: Historical claim. A statement about the past that historical evidence can test.
Review: Source checked. The cited passage was read, and it says this.

Supports
The cosmological constant problemsection I
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Theory · Review of the field
The source reads: theoretical expectations for the cosmological constant exceed observational limits ... some 120 orders of magnitude
The scanned text reads "bP" where the printed word is "by"; the excerpt skips it.
Context
Planck 2018 results. VI. Cosmological parameterssection 3.2, equation 15
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: a constraint on Ωₘ translates directly into a constraint on the dark-energy density parameter, giving ΩΛ = 0.6847± 0.0073
Notation restored: Subscripts and superscripts restored as the arXiv PDF (1807.06209v4) typesets them, read from glyph positions 2026-09-24; the abstract on arXiv gives H_0 and Ω_m the same way. The text as extracted reads: a constraint on Ωm translates directly into a constraint on the dark-energy density parameter, giving ΩΛ = 0.6847± 0.0073

What this does not establish

In 1989 the observed side of the comparison was an upper limit; Planck has since measured the dark energy density directly.

Later work looked for

A statement about what a 1989 paper says; not a finding later work revises.

Corrected

24 September 2026. Previously: “a mismatch set out in the review that made it a standing problem rather than a curiosity.” That the review made it a standing problem is a judgement no source read states; Weinberg’s own figure is stated instead. Also fixes a citation: the NASA page cited here does not discuss the problem, and the NASA dark energy page and the PDG review that do are cited instead.

Claim 60 · checked 24 September 2026 · AI-assisted audit

Where an answer might come from

Claim: Where an answer might come from

Kind: Framing. Signposting. It asserts nothing a source could check.

A particle we have not found yet

Claim: A particle we have not found yet

Kind: Framing. Signposting. It asserts nothing a source could check.

Claim: If dark matter is a particle that touches ordinary matter through something more than gravity, as WIMPs would, the next generation of detectors will be ten to a hundred times more sensitive than today’s, and is meant to keep going until neutrinos arriving from space start to drown out any signal.

Kind: Hypothesis. A proposed explanation, not an established one.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.6.3
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: These will increase the sensitivity to various DM candidates by 1-2 orders of magnitude, with the ultimate goal of exploring the parameter space until the backgrounds from astrophysical neutrinos will start dominating the event rates.
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.5
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: WIMPs: The WIMP paradigm has been a preferred framework

What this does not establish

The plans are the PDG review’s account of experiments in construction or design. A particle that feels only gravity would never register in such a detector.

Corrected

24 September 2026. Previously: “If dark matter is a particle interacting only through gravity and possibly the weak force, current and next-generation detectors may eventually reach the required sensitivity, or may rule the idea out entirely, which would itself be a major result.” A particle interacting only through gravity could not be detected this way at all. And detectors cannot rule the idea out entirely: the PDG review sets their limit where neutrinos swamp the signal. Now uncited no longer; the PDG review carries it.

Claim 63 · checked 24 September 2026 · AI-assisted audit

Claim: It may find the particle.

Kind: This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review: A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Claim 64 · checked 24 September 2026 · AI-assisted audit

Claim: If it does not, much of the range where the favoured candidates were expected will be closed, which would itself be a major result.

Kind: This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review: A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

The page’s own judgement of what a null result would mean.

Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.6.3
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: These will increase the sensitivity to various DM candidates by 1-2 orders of magnitude, with the ultimate goal of exploring the parameter space until the backgrounds from astrophysical neutrinos will start dominating the event rates.

Corrected

24 September 2026. Previously: “or may rule the idea out entirely, which would itself be a major result.” Narrowed: a null result closes a range, not the idea.

Claim 65 · checked 24 September 2026 · AI-assisted audit

A property of spacetime rather than a substance

Claim: A property of spacetime rather than a substance

Kind: Hypothesis. A proposed explanation, not an established one.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Energy (Review of Particle Physics, chapter 28)section 28.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: one can view the “cosmological constant”Λ as representing a constant energy density of the vacuum
Supports
Dark Energy (Review of Particle Physics, chapter 28)section 28.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: The title of this article follows the common but inexact usage of “dark energy” as a catch-all term for the origin of cosmic acceleration, regardless of whether it arises from a new form of energy or a modification of GR.

Other readings

A new kind of energy that changes over time, or a change to gravity itself, as the PDG review sets out.

Claim 66 · checked 24 September 2026 · AI-assisted audit

Claim: Dark energy may be the cosmological constant, or it may be a field whose strength changes over time.

Kind: Hypothesis. A proposed explanation, not an established one.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Energy (Review of Particle Physics, chapter 28)section 28.2.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: A cosmological constant is the mathematically simplest, and perhaps the physically simplest, theoretical explanation for the accelerating Universe. The problem is explaining its unnaturally small magnitude
Supports
Dark Energy (Review of Particle Physics, chapter 28)section 28.2.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: An alternative (which still requires finding a way to make the cosmological constant zero or at least negligibly small) is that the accelerating cosmic expansion is driven by a new form of energy, such as a scalar fieldφ(x) with potentialV (φ)

Other readings

The PDG review adds a third: that the acceleration comes from a change to gravity rather than any energy.

Claim 67 · checked 24 September 2026 · AI-assisted audit

Claim: In 2025 the DESI survey, combining its own measurements with the microwave background and supernovae, reported a preference for the latter at 2.8 to 4.2 standard deviations, depending on the supernova sample.

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

DESI with the microwave background alone gives 3.1.

Supports
DESI DR2 Results II: Measurements of Baryon Acoustic Oscillations and Cosmological Constraintsabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: When also including SNe, the preference for a dynamical dark energy model over ΛCDM ranges from 2.8− 4.2σ depending on which SNe sample is used.
Supports
DESI DR2 Results II: Measurements of Baryon Acoustic Oscillations and Cosmological Constraintsfigure 11 caption
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: The significance of rejection of ΛCDM is 2.8 σ, 3.8σ and 4.2σ for combinations with the Pantheon+, Union3 and DESY5 SNe samples, respectively
Qualifies
DESI DR2 Results II: Measurements of Baryon Acoustic Oscillations and Cosmological Constraintsabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: Unless there is an unknown systematic error associated with one or more datasets, it is clear that ΛCDM is being challenged by the combination of DESI BAO with other measurements and that dynamical dark energy offers a possible solution.

Later work looked for

Crossref and arXiv, 2025 on, "DESI DR2 dynamical dark energy supernova": the DES recalibration (Dovekie) and Union3.1 lower the range; Efstathiou argues a calibration offset; all now on the page.

Corrected

24 September 2026. Previously: “Some recent large surveys have reported hints of the latter, at 2.8 to 4.2 standard deviations depending on the supernova sample.” Attributed to the collaboration that reports it, since later supernova analyses revise the range.

Claim 68 · checked 24 September 2026 · AI-assisted audit

Claim: Corrections to the supernova samples since have narrowed that to 3.2 to 3.4;

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

Supports
Union3.1: Reducing Systematics in Supernova Cosmology with Self-consistent Measurements of Host Galaxy Properties for 2000 Type Ia Supernovaeabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: corresponding to 3.4σ evidence against a cosmological constant ... Updating the DESI-DR2+Planck+SN combined probe analysis with the recent Dovekie recalibration of DES-SN5YR (B. Popovic et al. 2025) or the updated Pantheon+, we find 3.4σ (was 4.2σ before Dovekie) and 3.2σ (was 2.8σ before our correction to Pantheon+)
Supports
Union3.1: Reducing Systematics in Supernova Cosmology with Self-consistent Measurements of Host Galaxy Properties for 2000 Type Ia Supernovaesection on combined constraints
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: The improved consistency among SN analyses is readily apparent; the range of evidence for ... tightened from 2.8–4.2σ to just 3.2–3.4σ.

What this does not establish

Union3.1 is itself a reanalysis by the Union team; its 3.2 to 3.4 covers DESI with Planck and each of the three corrected samples, all fitted with the same microwave background data.

Later work looked for

arXiv, 2026, Union3.1: this is the newer work; nothing later found.

Corrected

24 September 2026. Previously: “” Added: the range the page quoted has been revised.

Claim 69 · checked 24 September 2026 · AI-assisted audit

Claim: the team behind the sample that gave 4.2 now calls its result a weak preference,

Kind: Observation. Something measured or seen, as the named source reports it.
Review: Source checked. The cited passage was read, and it says this.

Supports
The Dark Energy Survey Supernova Program: A Reanalysis Of Cosmology Results And Evidence For Evolving Dark Energy With An Updated Type Ia Supernova Calibrationabstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Measurement
The source reads: Our results hold a significance of 3.2𝜎, reduced from 4.2𝜎 for DES-SN5YR, to reject the null hypothesis that the data are compatible with the cosmological constant. ... Using generally accepted thresholds for model preference, our updated data exhibits only a weak preference for evolving dark energy.

What this does not establish

The team still reports 3.2 standard deviations; "weak" is their word, from a Bayesian model comparison that puts the odds at about 5 to 1.

Later work looked for

arXiv, November 2025: the recalibration itself; nothing later that reverses it.

Corrected

24 September 2026. Previously: “” Added from the Dark Energy Survey’s recalibration of November 2025.

Claim 70 · checked 24 September 2026 · AI-assisted audit

Claim: and George Efstathiou has argued that a small offset between supernova samples could bring the most discrepant one into line with a constant.

Kind: What scholars argue. A report of what specialists argue, or where they disagree.
Review: Source checked. The cited passage was read, and it says this.

Supports
Evolving dark energy or supernovae systematics?abstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: A comparison of SN common to both the DES5Y and Pantheon+ compilations shows evidence for an offset of ∼ 0.04 mag. between low and high redshifts. Systematics of this order can bring the DES5Y sample into good agreement with the Planck ΛCDM cosmology and Pantheon+.
Supports
Evolving dark energy or supernovae systematics?abstract
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Astronomical observation · Observational study: associations, not causes
The source reads: The strength of the evidence for evolving dark energy ranges from ∼ 3.9σ for the Dark Energy 5 year (DES5Y) SN sample to ∼ 2.5σ for the Pantheon+ sample.

What this does not establish

The argument was made about DESI’s first data release and the original DES sample; the DES team disputed it.

Later work looked for

arXiv, 2025 on: the Dovekie recalibration moved the DES sample in the direction he argued; nothing that settles it.

Corrected

24 September 2026. Previously: “” Added: the named rival reading of the signal.

Claim 71 · checked 24 September 2026 · AI-assisted audit

Claim: These are hints, not conclusions,

Kind: What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Energy (Review of Particle Physics, chapter 28)section 28.4.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Any surprising result merits healthy skepticism, and the DESI findings are no exception. While the statistical significance is only moderate

Later work looked for

PDG dark energy review, revised August 2025, and the 2025 and 2026 supernova reanalyses: the signal is weaker, not stronger.

Claim 72 · checked 24 September 2026 · AI-assisted audit

Claim: and the Particle Data Group’s dark energy review treats them with “healthy skepticism”.

Kind: Quotes a source. The words of a named text, checked against the source.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Energy (Review of Particle Physics, chapter 28)section 28.4.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Any surprising result merits healthy skepticism, and the DESI findings are no exception.

Corrected

24 September 2026. Previously: “and the community treats them as such.” Attributed to a source that says it, rather than to "the community".

Claim 73 · checked 24 September 2026 · AI-assisted audit

A sign the model is wrong somewhere deeper

Claim: A sign the model is wrong somewhere deeper

Kind: Framing. Signposting. It asserts nothing a source could check.

Claim: Dark matter, dark energy and the expansion-rate discrepancy might be three symptoms of one missing piece of physics rather than three separate problems.

Kind: This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review: A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

The page’s own speculation.

Corrected

24 September 2026. Previously: “rather than three separate substances.” The expansion-rate discrepancy is not a substance.

Claim 75 · checked 24 September 2026 · AI-assisted audit

Claim: No theory of this kind has yet been shown to fit all the data.

Kind: This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review: A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

Follows from the next sentence and from the passage on modified gravity.

Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Usually such theories mimic the effects otherwise attributed to DM on a limited range of scales, but fail globally, and especially at the largest scales.

Corrected

24 September 2026. Previously: “There is no developed theory of this kind that survives contact with all the data.” Narrowed to what the evidence can carry, and given a source in the next sentence.

Claim 76 · checked 24 September 2026 · AI-assisted audit

Claim: Even replacing dark matter alone with modified gravity has so far worked on some scales and failed on others.

Kind: What the field holds. The settled view of a field, as a review, a consensus statement or a reference work gives it. Not one study.
Review: Source checked. The cited passage was read, and it says this.

Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Usually such theories mimic the effects otherwise attributed to DM on a limited range of scales, but fail globally, and especially at the largest scales.
Supports
Dark Matter (Review of Particle Physics, chapter 27)section 27.1
Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Reference work
The source reads: Key issues that at present appear highly problematic in the framework of theories of modified gravity without DM include (i) predicting the correct spectrum of density perturbations, (ii) predicting the observed anisotropy power spectrum of the CMB, and (iii) explaining weak lensing and X-ray observations of merging clusters

Other readings

The authors of the 2021 relativistic theory report that it fits the microwave background (claim 44).

Later work looked for

Crossref, 2021 on, "relativistic MOND cosmic microwave background": one 2021 theory reports a fit to the microwave background, noted in claim 44; the review’s judgement stands.

Corrected

24 September 2026. Previously: “” Added, with the PDG review as its source, so the passage is no longer uncited.

Claim 77 · checked 24 September 2026 · AI-assisted audit

What was read

A modification of the Newtonian dynamics as a possible alternative to the hidden mass hypothesisMordehai Milgrom, The Astrophysical Journal 270, page 365 · NASA ADS scan of ApJ 270, 365, with its OCR text layer; read abstract and introductionRead in full, 24 September 2026 · Copyright; quoted briefly
DESI DR2 Results II: Measurements of Baryon Acoustic Oscillations and Cosmological ConstraintsDESI Collaboration · arXiv:2503.14738; read abstract and figure 11Read in full, 24 September 2026 · CC BY 4.0
The cosmological constant problemSteven Weinberg, Reviews of Modern Physics 61, page 1 · University of Texas repository scan (hdl 2152/61094), retrieved through the Wayback Machine; read sections I to IIIRead in full, 24 September 2026 · Copyright; quoted brieflyThe scan’s OCR is rough; excerpts skip garbled runs.
Rotation of the Andromeda Nebula from a Spectroscopic Survey of Emission RegionsThe Astrophysical Journal · NASA ADS scan of ApJ 159, 379, with its OCR text layer; read abstract and section VRead in full, 24 September 2026 · Copyright; quoted brieflyExcerpts keep the OCR’s misreadings ("H n", "7?") so they can be matched.
A Direct Empirical Proof of the Existence of Dark MatterThe Astrophysical Journal Letters · arXiv:astro-ph/0608407v1; read abstract and section 1Read in full, 24 September 2026 · Copyright; quoted briefly
Planck 2018 results. VI. Cosmological parametersPlanck Collaboration / arXiv · arXiv:1807.06209v4 (9 August 2021); read abstract and sections 3.2 and 3.5, searched the restRead in full, 24 September 2026 · Copyright; quoted briefly
A Comprehensive Measurement of the Local Value of the Hubble Constant with 1 km/s/Mpc UncertaintyThe Astrophysical Journal Letters · arXiv:2112.04510v3 (18 July 2022); read the abstractRead in full, 24 September 2026 · Copyright; quoted briefly
Dark matterCERN · home.cern/science/physics/dark-matter/Read in full, 24 September 2026 · Copyright CERN; quoted briefly
Dark MatterNASA Science · science.nasa.gov/dark-matter/, "Dark Matter", by Chelsea Gohd; the cited address science.nasa.gov/universe/dark-matter-dark-energy/ now redirects hereRead in full, 24 September 2026 · NASA content, not copyrighted
What is Dark Energy? Inside Our Accelerating, Expanding UniverseNASA Science · science.nasa.gov/dark-energy/, by Chelsea GohdRead in full, 24 September 2026 · NASA content, not copyrighted
Rotational properties of 21 Sc galaxies with a large range of luminosities and radii, from NGC 4605 (R = 4 kpc) to UGC 2885 (R = 122 kpc)Rubin, Ford and Thonnard, The Astrophysical Journal 238, page 471 · NASA ADS scan of ApJ 238, 471, with its OCR text layer; read abstract and section VIII (discussion and conclusions)Read in full, 24 September 2026 · Copyright; quoted briefly
Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological ConstantRiess and others, The Astronomical Journal · arXiv:astro-ph/9805201; read the abstractRead in full, 24 September 2026 · Copyright; quoted briefly
Dark Matter (Review of Particle Physics, chapter 27)L. Baudis and S. Profumo, Particle Data Group · Review of Particle Physics, chapter 27, revised August 2025, PDF dated 1 December 2025; read sections 27.1, 27.5, 27.6 and 27.7Read in full, 24 September 2026 · Copyright; quoted brieflyPDF text extraction joins some words ("benchmarkΛCDM", "withXRISM"); excerpts keep that spacing so they can be matched.
Dark Energy (Review of Particle Physics, chapter 28)D. H. Weinberg and M. White, Particle Data Group · Review of Particle Physics, chapter 28, revised August 2025, PDF dated 1 December 2025; read sections 28.1, 28.2.1 and 28.4.1Read in full, 24 September 2026 · Copyright; quoted briefly
Modified Newtonian Dynamics (MOND): Observational Phenomenology and Relativistic ExtensionsBenoit Famaey and Stacy McGaugh, Living Reviews in Relativity 15, 10 · arXiv:1112.3960, abstract page and PDF; read abstract, sections 6.5.1, 6.6.4, 9.2 and 10Read in full, 24 September 2026 · CC BY (Living Reviews in Relativity)
New Relativistic Theory for Modified Newtonian DynamicsConstantinos Skordis and Tom Złośnik, Physical Review Letters 127, 161302 · arXiv:2007.00082v3 (14 October 2021), PDF text; read abstract, introduction and conclusionsRead in full, 24 September 2026 · arXiv non-exclusive distribution licence; quoted briefly
A Detailed MOND Modelling of the Bullet ClusterX. Hernandez, The Astrophysical Journal Letters 1008, L46 · Crossref record, abstractAbstract only, 24 September 2026 · CC BY 4.0
Status Report on the Chicago-Carnegie Hubble Program (CCHP): Measurement of the Hubble Constant Using the Hubble and James Webb Space TelescopesFreedman, Madore, Hoyt and others, The Astrophysical Journal 985 · arXiv:2408.06153v3 (17 March 2025), PDF text; read abstract, figure 1 and section 2, searched the restRead in full, 24 September 2026 · CC BY 4.0PDF text extraction drops subscripts ("H0"); the reader is shown them restored.
The Dark Energy Survey Supernova Program: A Reanalysis Of Cosmology Results And Evidence For Evolving Dark Energy With An Updated Type Ia Supernova CalibrationPopovic and others, Dark Energy Survey Collaboration · arXiv:2511.07517v3 (27 March 2026), PDF text; read abstract and the section on model preferenceRead in full, 24 September 2026 · CC BY-SA 4.0
Union3.1: Reducing Systematics in Supernova Cosmology with Self-consistent Measurements of Host Galaxy Properties for 2000 Type Ia SupernovaeHoyt, Rubin, Aldering, Perlmutter and others · arXiv:2601.19424v2, PDF text; read abstract and the section on combined constraints with DESI and the CMBRead in full, 24 September 2026 · CC BY 4.0
Evolving dark energy or supernovae systematics?George Efstathiou, Monthly Notices of the Royal Astronomical Society 538, 875 · arXiv:2408.07175v3 (4 February 2025), PDF text; read abstract and sections 1 to 3Read in full, 24 September 2026 · CC0 1.0 (arXiv version)