Question

1.          One of the aspects of the uncertainty principle, is that in making measurements, one changes the system being measured. Give an example of this in your everyday existence.

Answer 1

The uncertainty principle says that we cannot measure the position (x) and the momentum (p) of a particle with absolute precision. The more accurately we know one of these values, the less accurately we know the other. It tells us that there is a fuzziness in nature, a fundamental limit to what we can know about the behaviour of quantum particles. For sure it is very prominently observed at the subatomic levels and not at macroscopic level. Even then the subatomic phenomenon affected by the uncertainty principle eventually has real life implications. The questions why sun shines, whether space is empty and son can have intriguing answers in the uncertainity principle.

The uncertainity principle can explain alpha decay. In this alpha particles are two protons and two neutrons emitted by some heavy nuclei, such as uranium-238. These alpha particles are bound inside the heavy nucleus and would need lots of energy to break the bonds keeping them in place. As these alpha particles inside a nucleus has a very well-defined velocity, therefore by uncertainity principle their position is not so well-defined. What we can conclude from it is that there is a small probability that the alpha particle could, at some point, be found outside the nucleus. This despite the fact that the alpha particles does not have enough energy to escape. This phenonmenon is called "quantum tunnelling". The uncertainity principle explains the inexplicable alpha decay radioactivity.

Ow consider what is happening inside sun, a similar quantum tunnelling process in reverse direction. The protons fuse together and release the energy that allows our sun to shine. A daily life phenomenon seen across the globe by all of us and our life is dependent on it in the most important way. It is interesting that the temperatures at the core of the sun are not high enough for the protons to have enough energy to overcome their mutual electric repulsion. But, thanks to the uncertainty principle, they can tunnel their way through the energy barrier and carryout the fusion.