Age of the Universe
There are at least 3 ways that the age of the Universe can be estimated. I will describe
The age of the chemical elements.
The age of the oldest star clusters.
The age of the oldest white dwarf stars.
The Age of the Elements
The age of the chemical elements can be estimated using radioactive decay to determine how old a given mixture of atoms is. The most definite ages that can be determined this way are ages since the solidification of rock samples. When a rock solidifies, the chemical elements often get separated into different crystalline grains in the rock. For example, sodium and calcium are both common elements, but their chemical behaviours are quite different, so one usually finds sodium and calcium in different grains in a differentiated rock. Rubidium and strontium are heavier elements that behave chemically much like sodium and calcium. Thus rubidium and strontium are usually found in different grains in a rock. But Rb-87 decays into Sr-87 with a half-life of 47 billion years. And there is another isotope of strontium, Sr-86, which is not produced by any rubidium decay. The isotope Sr-87 is called radiogenic, because it can be produced by radioactive decay, while Sr-86 is non-radiogenic. The Sr-86 is used to determine what fraction of the Sr-87 was produced by radioactive decay. This is done by plotting the Sr-87/Sr-86 ratio versus the Rb-87/Sr-86 ratio. When a rock is first formed, the different grains have a wide range of Rb-87/Sr-86 ratios, but the Sr-87/Sr-86 ratio is the same in all grains because the chemical processes leading to differentiated grains do not separate isotopes. After the rock has been solid for several billion years, a fraction of the Rb-87 will have decayed into Sr-87. Then the Sr-87/Sr-86 ratio will be larger in grains with a large Rb-87/Sr-86 ratio. Do a linear fit of
Sr-87/Sr-86 = a + b*(Rb-87/Sr-86)
and then the slope term is given by
b = 2x - 1
with x being the number of half-lives that the rock has been solid. See the talk.origins isochrone FAQ for more on radioactive dating.
When applied to rocks on the surface of the Earth, the oldest rocks are about 3.8 billion years old. When applied to meteorites, the oldest are 4.56 billion years old. This very well determined age is the age of the Solar System. See the talk.origins age of the Earth FAQ for more on the age of the solar system.
When applied to a mixed together and evolving system like the gas in the Milky Way, no great precision is possible. One problem is that there is no chemical separation into grains of different crystals, so the absolute values of the isotope ratios have to be used instead of the slopes of a linear fit. This requires that we know precisely how much of each isotope was originally present, so an accurate model for element production is needed. One isotope pair that has been used is rhenium and osmium: in particular Re-187 which decays into Os-187 with a half-life of 40 billion years. It looks like 15% of the original Re-187 has decayed, which leads to an age of 8-11 billion years. But this is just the mean formation age of the stuff in the Solar System, and no rhenium or osmium has been made for the last 4.56 billion years. Thus to use this age to determine the age of the Universe, a model of when the elements were made is needed. If all the elements were made in a burst soon after the Big Bang, then the age of the Universe would be to = 8-11 billion years. But if the elements are made continuously at a constant rate, then the mean age of stuff in the Solar System is
(to + tSS)/2 = 8-11 Gyr
which we can solve for the age of the Universe giving
to = 11.5-18 Gyr
Allah The Allmighty says :
( 22-47 ) < And surely a day with your Lord is as a thousand years of what you number.>
It's mean that a Day by Allah is 1000 years in our reckoning in relation with the revolution of the Moon around the Earth ( it is the Hegire year) or the revolution of the Earth around the Sun ( Gregorian year).
And Allah says :
[70.4] To Him ascend the Angels and the Spirit in a day the measure of
which is fifty thousand years.
In this verse of the Sura 'The way of Ascent' ( it is the Way which take the Angels from the Earth to the Heaven after having excecuted the duties necessary for the Life of our Planet and the Kosmos. We can note that Allah doesn't say "fifty thousand years of what you number" because the day in question in this verse is a time measure of a Gods day ( which each day is 1000 years in our reckoning ) and this day is the age of the Universe which all events of our life from heaven to earth ascend to Him.
Let's convert these God's Years in our norms :
50,000 * 365.2422 (days in human year) = 18,262,110 Allah's Days.
One Day by Allah is corresponding 1000 years of our reckoning, therefore the Age of the Universe is :
18,262,110 * 1,000 = 18,262,110,000 years, that's to say that the age of the Universe is around 18, 1/4 Billions years. This number correspond exactly of the above article . After more than 14 centuries, Science and particularly Professor Jean-Claude Batelere of the "College de France" states that it is now a certitude that the Universe is 18 billions years old .
Note that others Secrets are hidden in these two verses.
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