Background
![[url=https://pixabay.com/en/big-bang-armageddon-explosion-pop-466312/]"Big Bang"[/url] by geralt is in the [url=http://creativecommons.org/publicdomain/zero/1.0/]Public Domain, CC0[/url]](https://www.geogebra.org/resource/QKHpjCzR/nf7rZnCVpMxpZTo3/material-QKHpjCzR.png)
The developments in our understanding of modern physics that began in the mid-1800s, that blossomed just after the turn of the 20th century and which have continued incrementally over the course of the past century through to the present day, are going to be the focus of the remainder of our course.
As you can imagine, there were many wrong ideas proposed over the past 150 years or so, which were soon discarded for lack of experimental agreement. However, there were also many wrong ideas which persisted for a long time due to agreement with experiment to some degree or another.
One famous example of such an incorrect idea is the Bohr atom. It is wrong because it tends to instill in students the idea that atoms are like little solar systems. The nucleus is the sun and the electrons are the planets, according to the model. Atoms are not made of hard, delineated particles like planets.
The reality is that the Bohr model tends to be taught to students even today due to its very limited usefulness in explaining spectral emissions from hydrogen and a very limited cohort of other atomic species. One should rightfully ask why such wrong models are propagated in this fashion. The answer is simply a combination of two things: Historical precedent in doing so, and the difficulty associated with teaching atomic structure the correct way.
In teaching modern physics many times over the years in the standard way, and in having been a student once myself, I have come to a bold conclusion: Following an historical sequence of developments is not equivalent to following a logical sequence. With the clarity of historical hindsight, I am going to delete certain usual topics that will otherwise perpetuate wrong ideas about our world or lead to obvious confusion and misconceptions in your minds about how nature works. In their place I will introduce topics and ideas that, to my knowledge, have never found their way into textbooks at the introductory level. It is likely that you have never heard many of these stories before.
The Bohr model, which you are bound to discuss in a chemistry class, will be replaced in this book by a more correct model that still comes to the same useful conclusions, but by using wave principles and quantization in a general way.
My goal, as always, is to help you form a coherent picture of nature with as few ideas and concepts as necessary. No doubt it will be a strange story - one that certainly exceeds the strangest of fictions. I am ever reminded, however, even as I type these words, that the strangest of stories is that we are on this journey together trying to understand our own underpinnings! Here we are investigating life together, and we didn't have anything to do with getting here. That the concepts and equations of which we are to soon speak somehow led to a universe in which we became self-aware, simply demands a moment of silence and humility.