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Hubble Constant


The Hubble constant, H0, is a measure of the rate at which space expands. Estimates of H0 are based on measures of the cosmological redshift of galaxies. The latest estimate, as of 2009, is: H0 = 74.2 ± 3.6 (km/s)/Mpc ≈ 2.4 x 10-18/s.

Based on observations of type 1a supernovae, the rate of expansion is believed to be increasing very slowly. If you assume it is constant, then the distance, d, between two remote galaxies is given by the formuma: d(t) = d0(1 + H0)t.

Suppose you want to know how long it takes for that distance to double. You would solve for t when d/d0 = 2.

d(t) = d0(1 + H0)t
d/d0 = (1+ H0)t
ln(d/d0) = ln(1+ H0)t = t · ln(1+H0)
t = ln(d/d0)/ln(1+ H0) = ln(2)/ln(1+ H0).
According to WolframAlpha, (Note: you must click "more digits" for precision.)
ln(2)/ln(1 + 2.4 · 10-18) = 2.88811 · 1017 s =  9.158 billion years.

If the expansion is accelerating, then apparently, space has barely had time to double in its presumed 13.7 billion year existance. Of course, the inflationary model, addresses that issue by saying there was as time of much greater exponential expansion soon after the Big Bang.


If the length of each side of a cube increases by 2.4 x 10-18, the volume of the cube increases by 7.2 x 10-18. So the volumetric expansion rate is three times the linear expansion rate. The volume of a region of space, defined by comoving boundaries, will double in
1/3 the time required to double the distances—about three billion years at the present rate.


How does H0 relate to FFMU?

The number of bubble walls per bubble is unknown, but let us suppose that it is a constant. In other words, the chaotic character of the foam is unchanging, despite expansion of space.
If the number of median-size ether-foam bubbles per cubic meter is constant, then the number of median-size ether-foam bubbles in a region of space, defined by comoving boundaries, will double in about 3 billion years. This suggests that the number of median-size bubble walls doubles in 3 billion years, which means that median-size bubble walls unpop at the rate of ???