Compare · The Dark Universe

TeVeS (Tensor-Vector-Scalar) vs Moffat MOG (Scalar-Tensor-Vector Gravity)

Modified Gravity / MOND· within family

	TeVeS (Tensor-Vector-Scalar) Frontier	Moffat MOG (Scalar-Tensor-Vector Gravity) Frontier
Proposed	2004	2006
Key figures	Jacob Bekenstein	John Moffat
In one sentence	Bekenstein's 2004 TeVeS is a relativistic theory that reduces to MOND in weak fields and to general relativity in strong fields, by adding a scalar and a vector field to the metric. It was the first serious relativistic MOND, but GW170817 constraints have substantially limited it.	Moffat's 2006 Modified Gravity (MOG, also called STVG) adds a vector field and scalar-field\|scalar fields to general relativity, effectively making Newton's gravitational coupling run with scale. It claims to explain galaxy rotation curves and cluster dynamics without dark matter, but the analyses are largely confined to one research group.
Predictions	How much background light a galaxy or cluster bends (gravitational lensing) should follow the TeVeS values set by the visible matter alone, not the larger ΛCDM values that assume a dark-matter halo; the cleanest test is the ratio of lensing mass to ordinary (baryonic) mass in colliding clusters The acoustic peaks in the cosmic microwave background, the regular ripples left by sound waves in the early universe, should come out with different heights and spacings than ΛCDM predicts, testable against Planck satellite data Tensor mode propagation speed potentially different from light speed (now tightly constrained by GW170817)	Galaxy rotation curves reproduced with effective scale-dependent gravity, no dark halos required Cluster mass profiles and light-bending (lensing) patterns should be explained by visible matter plus MOG's scale-dependent gravity, with no dark matter, the real test being whether one fixed set of MOG parameters works across many clusters rather than being retuned for each Specific deviations from GR at intermediate (galactic, cluster) scales; near-GR behavior in the solar system
Where it breaks	GW170817 constrains tensor mode propagation speed to match light speed to one part in 10^15; generic TeVeS configurations violate this and require fine-tuning to survive Cosmological perturbation analyses find TeVeS struggles to reproduce the CMB acoustic peaks and large-scale structure formation as well as ΛCDM The theory's field content (scalar plus vector plus free interpolating functions) is seen as baroque relative to ΛCDM's simplicity Active relativistic-MOND research has moved to newer frameworks (Skordis-Złośnik) that handle GW170817 from the start, leaving TeVeS as a reference rather than a live candidate	Many MOG fits use system-specific parameter values; critics argue this is parameter-fitting rather than unique theoretical prediction The [[bulk]] of MOG papers come from one research group; independent reproductions of the claimed cluster and lensing fits are scarce in the broader literature Cosmological survey pipelines (DESI, KiDS, DES, Euclid) do not include MOG as a baseline analysis; mainstream cosmology has not adopted the framework Like other modified-gravity proposals, MOG faces the Bullet Cluster (Clowe et al 2006) and CMB acoustic-peak challenges shared across the family
Key unresolved problem	The gravitational-wave speed problem: the 2017 GW170817 event showed gravity travels at the speed of light, yet most versions of TeVeS make gravitational waves travel at a different speed, so the theory survives only with heavy fine-tuning.	The independent-reproduction gap: almost all of MOG's successful fits to galaxy clusters, gravitational lensing, and collisions come from Moffat's own group, and outside teams have not confirmed them, so the wider community has not adopted the theory.
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TeVeS (Tensor-Vector-Scalar)

2004 · Frontier

Moffat MOG (Scalar-Tensor-Vector Gravity)

2006 · Frontier

Proposed

2004

2006

Key figures

Jacob Bekenstein

John Moffat

In one sentence

Bekenstein's 2004 TeVeS is a relativistic theory that reduces to MOND in weak fields and to general relativity in strong fields, by adding a scalar and a vector field to the metric. It was the first serious relativistic MOND, but GW170817 constraints have substantially limited it.

Moffat's 2006 Modified Gravity (MOG, also called STVG) adds a vector field and scalar-field|scalar fields to general relativity, effectively making Newton's gravitational coupling run with scale. It claims to explain galaxy rotation curves and cluster dynamics without dark matter, but the analyses are largely confined to one research group.

Predictions

How much background light a galaxy or cluster bends (gravitational lensing) should follow the TeVeS values set by the visible matter alone, not the larger ΛCDM values that assume a dark-matter halo; the cleanest test is the ratio of lensing mass to ordinary (baryonic) mass in colliding clusters
The acoustic peaks in the cosmic microwave background, the regular ripples left by sound waves in the early universe, should come out with different heights and spacings than ΛCDM predicts, testable against Planck satellite data
Tensor mode propagation speed potentially different from light speed (now tightly constrained by GW170817)

Galaxy rotation curves reproduced with effective scale-dependent gravity, no dark halos required
Cluster mass profiles and light-bending (lensing) patterns should be explained by visible matter plus MOG's scale-dependent gravity, with no dark matter, the real test being whether one fixed set of MOG parameters works across many clusters rather than being retuned for each
Specific deviations from GR at intermediate (galactic, cluster) scales; near-GR behavior in the solar system

Where it breaks

GW170817 constrains tensor mode propagation speed to match light speed to one part in 10^15; generic TeVeS configurations violate this and require fine-tuning to survive
Cosmological perturbation analyses find TeVeS struggles to reproduce the CMB acoustic peaks and large-scale structure formation as well as ΛCDM
The theory's field content (scalar plus vector plus free interpolating functions) is seen as baroque relative to ΛCDM's simplicity
Active relativistic-MOND research has moved to newer frameworks (Skordis-Złośnik) that handle GW170817 from the start, leaving TeVeS as a reference rather than a live candidate

Many MOG fits use system-specific parameter values; critics argue this is parameter-fitting rather than unique theoretical prediction
The [[bulk]] of MOG papers come from one research group; independent reproductions of the claimed cluster and lensing fits are scarce in the broader literature
Cosmological survey pipelines (DESI, KiDS, DES, Euclid) do not include MOG as a baseline analysis; mainstream cosmology has not adopted the framework
Like other modified-gravity proposals, MOG faces the Bullet Cluster (Clowe et al 2006) and CMB acoustic-peak challenges shared across the family

Key unresolved problem

The gravitational-wave speed problem: the 2017 GW170817 event showed gravity travels at the speed of light, yet most versions of TeVeS make gravitational waves travel at a different speed, so the theory survives only with heavy fine-tuning.

The independent-reproduction gap: almost all of MOG's successful fits to galaxy clusters, gravitational lensing, and collisions come from Moffat's own group, and outside teams have not confirmed them, so the wider community has not adopted the theory.

Reader vote

No votes yet