Radiometric dating and the age of the universe

Age of the Universe

Understanding the origin of the universe and the mysteries behind the complex machinery has always been a fascinating subject for the inquisitive minded. Questions of the nature as to whether the universe is infinite or is it well confined within its own boundaries, the exact time period in which the universe came into being, the ultimate end and other cosmological complexities of the universe are rather intriguing. The inherent curiosity to unravel the secrets behind the universe has long driven scientists in to exploring the beginnings of our universe. In the process methods have been evolved which have more or less traced down the age of our universe. Let us have a brief outlook into one of the well-known methods available for calculating the age of earth.

Radiometric Method

Currently radiometric-rating technique is one of the valid methods of calculating the age of the universe. Radiometric rating method is based on the principle of radioactive decay of one isotopic element into another isotopic element. Since the radioactive decay of certain elements like Potassium / argon, rubidium -strontium is well-known (half life periods) we can evaluate the age of any chemical substance by measuring the changing ratios of the two isotopes. (Parent / child) Using this method we can approximately arrive at the age of chemical elements. For example Rubidium87 and strontium86 are two elements present in rocks. Rb87 undergoes radioactive decay to form sr87. The half-life period of this radioactive decay is 47 billion years.

So as an example for calculating the age of a rock we need to calculate the ratio of sr87/sr86. Applying the linear fit we get Sr.-87/Sr.-86 = a + b*(Rb-87/Sr.-86). We can solve the slope of the equation b= b = 2x - 1 where x is the number of half-life period of the rock. Using these technique scientists have identified the oldest meteorite to be around 4.6 billion years old. [Edward L. Wright] It has to be understood that the radiometric technique is not without any drawbacks. Our main cause of concern with such a technique is that it is purely based on the changing ratio between the parent child isotopes. (Rubidium to strontium or Thorium to Neodymium etc.). This would work perfectly only in a completely isolated system where there is no external addition or removal of the parent / daughter isotopes.

Astronomer Harvey Butcher applied the Radiometric dating technique to calculate the age of the universe. Using spectroscopy he was able to find out the Thorium/neodymium ratio in the sun and neighboring stars. Neodymium is the radioactive product of Thorium. Each of these isotopes have their own distinct absorption spectra. Butcher's experiment found that the Thorium to Neodymium conversion was negligible and most of the initial Thorium was still intact even in the oldest of the stars. So the result from butcher's experiment suggests that the age of the universe is around 8 billion years. But the problem with the radiometric approach is that the success of the method depends of our precision in assuming the initial concentrations of the isotopes. [Jon Covey]

Conclusion

The different techniques for arriving at the age of the universe are based upon different assumptions. For example the red shift method of calculating the age of the universe is dependent on the belief that the universe is continuously expanding. (Based on the Big bang theory). The radiometric dating method again depends on the correct appreciation of the initial concentration levels of the isotopes. In conclusion we can state that each method is dependent on certain assumptions, which we are yet to validate with any degree of accuracy. However there is no question of doubt that we are moving forward in our attempts at finding order in a chaotic universe.