Presentation #326.04 in the session Dark Matter & Dark Energy.
Deep space observations of the James Webb Space Telescope (JWST) have revealed that the structure and masses of very early Universe galaxies at high redshifts (z~15), existing at ~0.3 Gyr after the Big Bang, are as evolved as the galaxies in existence for ~10 Gyr. The JWST findings have thus challenged the ubiquitously accepted ΛCDM cosmological model, which predicts the Universe’s age as 13.7 Gyr. While tired light (TL) models comply with the JWST data, they cannot adequately explain isotropy of the cosmic microwave background (CMB) observations or fit the supernovae distance modulus vs. redshift data well. We have developed hybrid models that include the tired light concept in the expanding universe. The hybrid ΛCDM model fits the supernovae type 1a data well but not the JWST observations. I will present a model with covarying coupling constants (CCC), starting from the modified FLRW metric and resulting Einstein and Friedmann equations, and a CCC+TL hybrid model. They fit the Pantheon+ data admirably, and the CCC+TL model is compliant with the JWST observations. It stretches the Universe’s age to 26.7 Gyr with 5.8 Gyr at z=10 and 3.5 Gyr at z=20, giving enough time to form massive galaxies. Thus, it resolves the ‘impossible early galaxy’ problem without unrealistic models, such as those requiring the existence of primordial black hole seeds, rapid formation of massive population III stars, and super Eddington accretion rates. I will show how the CCC model can be viewed as an extension of the ΛCDM model with a dynamic cosmological constant expressed in terms of the constant α defining the variation of CCC. Thus, CCC+TL model has only two parameters, the Hubble constant H0 and α, determined by fitting the Pantheon+ data, yielding the same H0 and goodness-of-fit parameters as the standar ΛCDM model. The tired light redshift as a fraction of expanding Universe redshift small; it starts at 22% at z≈0 and declines slowly to 20% at z=10, to 18% at z=20, and to 3% at z=1000.
The CCC model is inspired by the varying gravitational constant predicted by Dirac from his large number hypothesis. From the local energy conservation laws, the variation of speed of light c, the gravitational constant G, the Planck constant h, and the Boltzmann constant k must follow G~c3~h1.5~k1.5 when distance is measured with c. This leads to G ̇⁄G=3 c ̇⁄c=1.5 h ̇⁄h=1.5 k ̇⁄k, and therefore their variation can be represented by a single dimensionless function f(t), i.e., if one constant varies, then all of them do. Fixing one, fixes all. Using f(t)=exp[α(t-t0)] one gets α=-0.66H0 (=c ̇⁄c). Since G ̇⁄G=3 c ̇⁄c, we get G ̇⁄G=-2.0H0, about the same predicted by Dirac.