Duality of Expansion of Universe with increase of Mass-energy or Gravitational "constant"
A recent paper offered the sugestion that the Universe is not expanding, rather the mass of matter in it has increased over time. That is, the density of stuff has increased. Given that Mass-energy defines a time measure through E=hf, (Planks equation) an increase in the mass of matter as the Universe has evolved would mean that the light associated to it would become more and more blue-shifted with time. Conversely looking back through time as we do when we look out at the night sky, the more distant galaxies formed of this less dense matter would appear red-shifted compared to the matter of today (in our labs giving of the standard candle spectra).
What this idea does is present an explanation with no measurable difference to the expansion notion. Turning a constant (inertial mass) into a (time dependent) scalar field is comparable it seems to the theories of Brans-Dicke and Sciama who have similarly treated the constancy of Newton's gravitional strenth, G with caution by rendering it rather as a spatially dependent field.
Is the expansion (spread of distances between matter) just a complimentary way of saying that mass has ossified over the years, that the coupling strength of inertial mass has increased over time? It is not intuitive. If we embrce the Machian principles of Sciama's iniital idea that ineertial mass should be derived from the distant but receding set of stars can that mass be instead seen to increase as the stars stay fixed? Why should matter get denser over time? only the accumulaitng pull of the negative Entropy of gravity can be the explanation. Given that locally accelerated non-inertial motion is equivalent to a gravtational pull does this mass-ossifying admit a strong equivalence priincple equivalent?
Clarity at the looking back through time is probably needed here. It is "through" not 'in' time we talk about. When we look at the sky we see a conflation of starlights, from light first emitted at the time of the Battle of Hastings to the the first mammal emerging from water and beyond. It is not a snapshot cutting through time but an ever accumulating spectral fingerprint of our corner of the universe's history.
What we see out in our night sky is after all, but our preferential (inertial) view of the whole history of a perfect fluid in which the very cells that the universe is modelled to comprise cannot (as is required by the Cosmological principle that asserts our non special -Copernican viewpoint) be the same type of cells. The cells of the fluid that we see rather are not homogenous or isotropic . From our time-travelling viewpoint the cells of the fluid are variable, as time (and gravity) have now aggregated large scale clusters of galaxies which were once a teaming plasma fireball 300,000 years after the Big Bang.
Cells of homogeneity simply do not make sense from our seeing (through telescopes) point of view. But we do observe spatial homogeneity to justify the Cell model, when we look out, in a cut across time, that is the Cosmic Background Radiation Red-Shifted remnant.
When we observe it is not like looking at a movie seeing at once and at every subsequent instance the full spatial entirety of the universe. Our field of view is limited by the finiteness of spped of light doublefold.
We are not so to speak, seeing photgraphs of our family tree spatially seperated by lines that represent time, but instead the ghostly figures of our forefathers at the shoulders of our fathers. The father having latterly joined the journey of the forefather to form an image on our photgraph. Arguments against the notion of Expansion (even with the CMBR remannt) make the point that there is no sense to talk of expanding length scales when there is no independent length rod (in an alterntive Paris lab in a seperate static universe say) with which to compare lengths. Our relativism for spatial separation is but the the journey time of light emitted between seperated particles of mass and the finiteness of the speed of light makes distance and time equivalent. Now if it is argued rather that mass is increasing as time ticks over and commensuratley Energy is too given its proportionality to mass distance can stay fixed if the spped of light remains a true constant through time. One could argue that Mass and c altered in complimentary ways if you allow c to evolve with time. The latter doesnt seem unreasonable given that we could argue that there will be different vacuum energies (due to different energy-densities existing) through time.
