Viswanathan K's Thoughts

My dad is hugely interested in physics. (He keeps telling me that he used to be interested, but not anymore. But that’s another story…). Unlike Rutherford who called other fields “stamp collecting”, my dad doesn’t have contempt for other fields. But I wonder whether even with his non-Rutherfordian worldview, my dad knew how totally unrelated fields drove physics even in the last century. Everyone can imagine how somewhat similar fields like chemistry could influence physics, but geology? Or paleontology (remember Ross from Friends ? The field of fossils and dinosaurs)? How could they possibly have pushed the boundaries of physics? But influence they did. It all started when people tried to compute the age of the earth a couple of centuries ago. As geologists started analyzing layers of rocks, they could not assign values to the ages of any of these layers since there was no known method to do so at that time. Then a renowned physicist got involved in the effort: Lord Kelvin...

C14 dating, as mentioned in my last blog , is based on carbon. Which means, as we learnt at school, it can only be used for dating organic materials. How then are does one find the age of inorganic (non-Carbon) materials? Like the age of the earth, for example? That makes for an interesting tale. One always associates radioactivity with terrible things like cancer, nuclear bombs and Chernobyl. And yet, it was the principle of radioactivity that helped figure out the age of the earth! Radioactivity is the decay of one element into another, along with the emission of the catastrophic radiation. The rate of decay for different radioactive materials is fixed. That property means radioactive materials can be used like clocks. The idea was simple: uranium decays into lead. So if you found the ratio of uranium to lead in really, really old rocks, you could derive the age of the earth. The devil lay in the execution of the idea. How do you find uncontaminated really, really old ...