G
= V / (t2 * M)
So we have:
M / V = 1 / (G * t2) = ρ =
Universe's density
In physical cosmology, the age of the universe is the time elapsed since
the Big Bang.
The best measurement of the age of the universe is 13.798±0.037 billion
years
(13.798±0.037×109 years
or 4.354±0.012×1017 seconds)within the Lambda-CDM
concordance model.
Planck Collaboration (2015). “Planck 2015 results. XIII. Cosmological
parameters”
The age of the Universe can be estimated by means of other methods too.
There are at least 3 ways:
- The age of the chemical elements that gives a value of
14.5+2.8/-2.2 Gyr.
(Nicolas Dauphas Nature 435, 1203-1205 (30 June 2005))
- The age of the oldest star clusters that gives a value of 14.1 +/- 2.5
Gyr
(Shinya Wanajo Astrophys.J. 577 (2002) 853-865)
- The age of the oldest white dwarf stars that give a value of 12.8 +/-
1.1 Gyr.
( Harvey B. Richer: Astrophys.J.574:L155-L158,2002)
Replacing known values:
ρ = 1 / (G * t2) = 1 / ( (6.67408*10-11) * ( 4.354 *
1017)2 )
ρ = 1 / ( (6.67408*10-11) * (18.957316*1034)
)
ρ
= 1 / (126.52264356928 * 1023) = 0.0079 * 10-23 Kg/m3 = 7.9 * 10-26 Kg/m3
ρ
= 7.9 * 10-29 g/cm3
It is important to note that the achieved ρ is
the total mass_energy density of the Universe. In other
words, it is the sum of a number of different components including both
normal (baryonic) and dark matter as well as the dark
energy .