Hubble age

Robert Dicke (1961) later hit on an interesting rejoinder. As noted, Dirac had taken it to be more than mere coincidence that the Hubble age should happen to have the value A, thus linking it to the other two cosmic features. Dicke showed that this was indeed not a coincidence, but his explanation was quite different from Dirac s. Observers can exist in the universe only after heavy elements have had time to form, and within the maximum lifetime of a massive star. Calculations show that, given the components from which the other two constants are constructed, the Hubble age during the epoch of man, as Dicke called it, would necessarily be of the order of A. The relationship between H and the other two does not therefore indicate an invariant relationship, as Dirac thought, but is a selection effect, a constraint set on the value of Tby the conditions of human observership. Ihere is no reason, then, to make the gravitational constant or the mass of the universe vary. 

In the meantime there is another debate among cosmologists to decide between the three possible expansion models with /C = 0 or 1. The importance of this debate is underlined by Figure 6.3 which shows the relationship between Hubble age and actual age, Ta for an expansion model. 

Figure 6.3 Relationship between actual and Hubble ages of the Universe...

However, most distressing is the selective use of astrophysical data in support of standard cosmology. Twenty years after the discovery of massive inhomogeneities in the form of supergalactic clusters, the mere formation of which would have taken much longer than the alleged Hubble age of the... 

An equivalent linear relationship Av = Hx may be assumed in curved space. In the limit Av oc, H —> l/to as before, but now l/H = Tq/c is interpreted to define an upper bound to some radius of the curved universe, rather than its age. Unlike the Hubble age, the predicted radius is not in conflict with any known observation. 

The age of the Universe is the inverse of the Hubble constant. The system of units must first be rationalised to convert all of the light-years into kilometres and then years, so that ... 

Baade revises Hubble s distance scale, so Big Bang theory not flawed by giving age of Universe less than that of the Earth. 

M. Schwarzschild, A. Sandage and others pioneer theory of stellar evolution without extensive mixing and apply it to HR diagrams of globular clusters getting ages of several Gyr, comparable to the new inverse Hubble constant. 

Edwin Hubble measured the distance of several Cepheids in the great Andromeda nebula and found that it was situated far beyond the globular clusters in the retinue of the Milky Way. It was then that the milky designation galaxy made its entry into astronomy. The age of extragalactic astronomy had... 

Because the matter density VLmh2 was fairly well constrained by the amplitudes, the positions of a point in Figure 9.21 served to define a value of the Hubble constant. The size of the points in Figure 9.21 indicates how well this derived Hubble constant agrees with the H0 = 72 8 from the HST Key Project (Freedman et al., 2001). Shown as contours are the Ax2 = 1, 4, 9 contours from my fits to 230 SNe la (Tonry et al., 2003). Clearly the CMB data, the HST data, and the SNe data are all consistent at a three-way crossing that is very close to the flat Universe line. Assuming the Universe actually is flat, the age of the Universe is very well determined 13.7 0.2 Gyr. 

Li Y-J, Hauser MA, Scott WK, Maifin ER, Booze MW, (Jin XJ, Walter JW, Nance MA, Hubble JP, Koller WC, Paliwa R, Stem MB, Huier CB, Jankovic J, Goetz CG, Small GW, Mastaglia F, Haines JL, Peri-cak-Vance MA, Vance JA (2004a) Apolipoprotein E controls the risk and age at onset of Parkinson Disease. Neurology 62 2005—2009. 

In the age of the Hubble Telescope, the mirrors for such giant structures often use as much as 20,000 lb (9,000 kg) of a Pyrex-like glass called borosilicate. Such a vast stretch of material, 7 yd (6.5 m) across, cannot be ground normally. Surface irregularities could too easily develop. The material is melted and whirled in a huge circular furnace until it settles into shape. Afterwards the exterior is polished by a computer-programmed machine, to avoid human error as much as possible. 

If the universe is expanding, the galaxies were once much closer to each other. If the rate of expansion has been unchanged, the inverse of the Hubble constant, H, would represent the age of the universe. 

To confirm her initial observations, she decided to use the Hubble space telescope s new wide-field camera, which more clearly resolved the star grid, some 7 billion light years from Earth. Because peering at distant stars is like looking back in time, the images revealed a star grid that existed when the universe was 60 percent of its current age. 

Despite its fimdamental importance Hubble s constant is also the most fiercely disputed concept in standard cosmology because of its decisive role in predicting the age of the universe. The very first version of expanding-universe cosmology was widely rejected as the original value of the constant,... 

Ho = 530kms Mpc , derived from Hubble s linear plot, predicted an age of only 1.2 x 10 years, which is demonstrably less than the age of the Earth. 

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