Some parts of the notes are still under development and are yet to reach their final form. Any feedback is welcome. Please write to [email protected].

Introduction

One of the key lessons of 20th-century physics is the realization that nature, at its very core, is quantum mechanical. This fact is often blatantly ignored in high school curriculums. Quantum theory, when mentioned at all, is alluded to be this mysterious, enigmatic entity that apparently only manifests itself at the scales of atoms or smaller. This is a gross oversimplification, bordering on being inaccurate. Everything in nature is essentially quantum mechanical. The reason most of our worldly affairs can be described very well by Newtonian (also called classical) mechanics is simply that under certain situations, quantum mechanics can be well approximated by Newtonian mechanics.

Physicists have studied quantum mechanics for nearly a century. Numerous experiments have again and again confirmed its validity and sharpened our theoretical understanding of it. Certain mathematical predictions of quantum mechanics have been matched with an experimental outcome up to 12 decimal places! This is by far the most successful match between theory and experiments, not just for physics but for any science human beings pursue! Evidently, such an achievement is impossible if, to believe in popular folklore, “nobody truly understands quantum mechanics!” There are many things we still do not understand, but such is the nature of any scientific inquiry. To fully appreciate what we do not understand, we must first demystify what we do understand.

<aside> 💡 Nature is fundamentally quantum mechanical. Classical mechanics is just a useful approximation of quantum mechanics for a limited set of circumstances.

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Contents:

Some parts of the notes are still under development and are yet to reach their final form. Any feedback is welcome. Please write to [email protected].

Introduction