The laws of physics comprise a very powerful set of tools for the sake of answering fundamental questions about nature. These laws apply in areas that include the very smallest subatomic structures as well as the very largest astronomical ones. In fact, physics forms the foundation for many other sciences, and using a physics lens allows deeper understanding in many disciplines. [br][br]As an example, the laws and rules of chemistry are direct consequences of the laws of physics. All the rules about electron orbitals, bond formation, ionization energies, chemical structures, come from laws of quantum physics. Chemistry is really about memorizing what are ultimately the results of very complex physics calculations. Chemistry is useful because it would simply be impossible to discuss the chemical world if we had to perform quantum calculations every time we wanted understanding of a process or a structure. In fact, many calculations are so big that they'd take weeks, months, or longer even on a supercomputer cluster. Regardless, the point remains that chemistry is results of physics applied to atoms and smaller molecules.[br][br]I personally earned my Ph.D. in theoretical physics from Purdue University, and worked on biological systems. What this means is that I spent years studying the details of how proteins perform their functions. I didn't do this like biologists do this. Rather, I calculated protein motions according to laws of physics, and worked to understand how the motions (dynamics) and structures relate to protein function. [br][br]Biologists study life in a very different way and at a different level than physicists who work on biological systems, as I did. A large part of biology is related to identifying systems and their interactions with one another. They do the hard work of what I would call "cataloging". The biological view is similar to viewing traffic from the sky. Using this analogy, they get the big picture of traffic flow and interactions, but they miss the internal combustion engine and the driver's behavior. Molecular biology is amazing, and teaches all about the molecules of life, genes and reproduction. After such a course, however, one is often left with a good understanding of what molecules exist in the cells, and which ones interact with one another, but not with a clear sense of [i]how[/i] they really do what they do. "How" is a much deeper question, and one which requires a closer perspective. It requires viewing individual atomic motions and molecular structures in detail. [br][br]One important lesson I learned in my studies is that as smart as we sound oftentimes, in reality there are way more questions than there are answers. In fact, the more you know, the more you realize you don't know. Ignorant people are often humble since they're aware of their ignorance. Educated people often lose their humility because they think they know something. I maintain that well-educated people are only properly educated once they have become humble once again - or for the first time if they didn't start out that way. There are endless things we don't know and spectacular mysteries waiting to be unraveled. It's a shame when we act too sure of ourselves, or worse yet, when we think we understand a process just because we've assigned a name to it. This is not uncommon. [br][br]It is easy for a biologist or biophysicist to speak of some protein-enzyme reaction while sounding intelligible even though the dynamics and stuctures required to allow such a reaction are nearly impossible to predict or even calculate. It is easy for a physicist to speak intelligibly of the big bang and stellar evolution even though there are many details of those theories that are still complete mysteries. [br][br]I am filled with wonder when I look at nature - but especially at complex life. Before I saw the details and considered the physics of life - most of which scientists still can't comprehend - I did not have a proper respect for life. In fact, almost on a daily basis now I am struck by the strangeness or wonder of life and existence itself. Look at your hand. You can move your fingers with a thought, and perhaps use those fingers to play a guitar built by another person's hands. That music you play on that guitar may be an improvised product of your emotion, and may move others who are listening to tears as the music causes them to recall memories of a sensitive moment of their childhood. We are strange and wonderful creatures. Very little of that is able to be understood by physics or science in general at the present time.

Other physicists study areas such as solid state matter perhaps with a focus on high temperature superconductors or a new carbon nanomaterial. Yet others study fundamental particles, hoping to find a complete set of the most fundamental constituents of nature. Yet other astrophysicists study astronomical systems - perhaps the evolution of stars or the structure of space and time or many other topics.  [br][br]To me there is wonder in all of those subjects, but life is by far the crowning jewel of creation.  In fact, it is often stated that on your shoulders is the most complicated structure in the known universe.  Your brain is an astonishingly complex quantum computer, the details of which we are only beginning to uncover.  I have always suspected that somehow we won't ever be able to tame neuroscience. After all, we are attempting to use brains to study brains. It seems like it ought to take a more complex object to learn about a simpler one in a finite amount of time. Maybe I'm wrong. Regarding this most complicated structure, I would suggest that DNA is in fact more complex. Perhaps not in physical structural complexity, but certainly in information content and the associated complexity of that information. The brain and its structure is, after all, encoded in your DNA, along with every other aspect of your biology that will among other things keep that brain of yours alive. The information content and complexity of DNA is often grossly underestimated by those who only count the number of base pairs and lengths of the sequences. They miss the whole point. [br][br]In any case, it's a good thing you have that brain of yours. You'll need it in this course (and others to follow) to understand the much simpler things in nature relating to projectiles, collisions, electricity, magnetism, quantum physics, relativity and many more interesting topics. [br][br]Besides areas of physics, all the major branches of engineering may be seen as applied physics. In this sense you can consider this course as a future investment. There isn't any better subject than physics in which to invest your time and efforts if the goal is to understand some branch of nature, engineering or technology.

It is important to point out that physics is all about cause and effect relationships in nature. When we speak of laws of nature, what we mean is equations that have predictive power. We want to be able to observe the present state of a system and predict the future state, or perhaps imply what the past looked like. I shoot a bullet at a given angle and speed and you tell me where and how it lands. Given all the known interactions between the bullet and its surroundings (causes) we want to predict the future landing site and trajectory (effect).[br][br]What physics cannot answer or even rightfully address are questions of purpose or origins. Who shot the bullet and why? While I'm speaking of a bullet, it is also not within the scope of physics to address where the universe came from or whether it has a purpose. I mention this because my physicist colleagues around the world often overstep this boundary. [br][br]Every thinking human wonders about these topics, and rightfully so. We are confined to a physical universe (box), the laws of which we can study, but we can't peer outside that box in either a literal or figurative sense using instruments or the laws of physics. What the laws tell us is that the box (universe) hasn't always been here. We suspect from measurements and physical laws that it had a beginning called the big bang, but physics can not rightfully discuss the "why" or the purpose of such a beginning. From inside the box we can also see from the laws of physics that the end will not look anything like the beginning. It should be noted that at the present time the big bang model, and the details of inflationary theory are failing to match empirical data. We are much less sure today about the universe, its structure, and its origins than we were even a handful of years ago. [br][br]It is also worth mentioning that questions about what may have existed before the big bang are difficult for at least two reasons: The first is that if what was before was not physical or not made of the same stuff as our universe, then physics can say nothing about it. The other difficulty is the word "before". Before is a term related to time. Time is a product of, and is linked to the laws of nature governing our universe. One place this can be seen is in the area of statistical mechanics. (Those are discussions you'll revisit if or when you take upper division physics.) In any case, if there was anything before the universe began, then it was likely timeless. It is difficult for us to imagine existence apart from time, being ourselves subject to laws of nature, but without a universe and its laws, that's what we'd have: Timeless existence. [br][br]Here I must admit that physics often takes us to the boundary over which we tread on the turf of philosophy or religion. I enjoy those excursions. I hope as a thinking individual that you will take your own excursions to those places as well. It obviously isn't the focus of this course, however.[br][br]I took you to that boundary to point it out to you. Without understanding of such boundaries, intelligent and productive conversations about some of life's greatest mysteries cannot easily take place. I have always sought answers about life, and have found answers in physics classrooms, philosophy classrooms and religious institutions. I don't find the tensions that so many people seem to think exist between those areas of inquiry. In any case, I look forward to taking a small part of that journey with you.