The answer is “we are not sure, yet.”

It’s almost a century since the birth of Schrodinger Equation-the equation that tells us how things move if they are really small.

But there are still a lot of mysteries surrounding quantum mechanics. For example, quantum mechanics made a lot of predictions that can only be seen under very extreme circumstances. And as such, we don’t see these “quantum effects” everyday. See the link below for a famous quantum cat.

http://www.youtube.com/watch?v=IOYyCHGWJq4

This is the question that I asked myself when I decided to take a Phd in physics a year ago. I still ask myself this now and then, and get confused. I hope 4 years efforts could bring me closer to the answer.