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AGE OF TREE, ROCK, EARTH, SUN AND UNIVERSE

 



 Cut the trunk of a age old tree.  We can see number of rings in the cross section.  Each ring is formed during a year.  The count of rings gives the age of tree.

      Earth rock and meteorites that has fallen on the earth has a composition of potassium-40 and organ-40.  Potassium is the radioactive element.  It emits radiation and decays into organ.  Radioactivity never stops.  The original potassium atoms are slowly converted into organ.  By counting the number of radioactive potassium atoms and stable organ atoms, one can estimate the age of rock using this formula.

 N = n*e^(-R*T)

 N - number of radioactive atoms at present (potassium)
n- Number of radioactive atoms during the formation of        rock(potassium + organ)
R - Radioactive constant of potassium
T - Age , time elapsed since the formation of rock.
e - Maths constant

      This is called radiometric dating.  Since the rock belongs to earth, it will give the age of earth.  The meteorite will give the age of solar system.  The age of earth and solar system is same and it is 4.56 billion years.

      Big bang theory says ; entire universe was contained in a tiny atom.  At one fine moment, it exploded.  The matters were thrown out and almost the entire universe was created in a few minutes after the big bang.  The stars and galaxies formed during the explosion continue to move apart and consequently the universe continue to expand even today.  Using the rate of expansion at present, we can estimate the age of universe.(the velocity of moving star is determined using Doppler shift in spectrum)  The age is 13.77, error 0.059 billion years.

 Post script:  "Suppose a 'man' observes our earth from distant galaxy", he will not be seeing the modern man holding the smart phone.  He may see the first world war or even dinosaurs moving about.  Because he will be receiving that scene today even at light speed.  So universe is a kind of "time machine".  

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  1. Jyotirmoy Sarkar18 April 2017 at 21:35

    Very nice post Sir, loved reading it.
    and yes...the stars we see in the sky some are already destroyed long years ago and the light from them still coming to earth.

    ReplyDelete

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