I heard there are many alternative hypoteses for cosmological redshift, e g Fred Hoyle' s variation of mass and tired light. There are other ones?
Thanks.
https://en.wikipedia.org/wiki/Recombination_(cosmology)
Was a matter density right after the decoupling low enough to consider the vacuum as the actual vacuum, and not the medium through which the light propagates with the speed lower than ##({\epsilon_0\mu_0})^{-1/2}##? I'm asking this in context of the calculation of the observable universe radius, where the time integral of the inverse of the scale factor is multiplied by the constant speed of light ##c##.
A few years back there was an issue called the Hubble tension where the observations were nor matching up to predictions when looking at the Early and late time data.
I had heard that one possible explanation is due to our being in an underdense region but have also read a counter paper to this.
Has there been any resolution or is the issue still being resolved ?
Why was the Hubble constant assumed to be decreasing and slowing down (decelerating) the expansion rate of the Universe, while at the same time Dark Energy is presumably accelerating the expansion? And to thicken the plot. recent news from NASA indicates that the Hubble constant is now increasing. Can you clarify this enigma? Also., if the Hubble constant eventually decreases, why is there a lower limit to its value?