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Introduction to the class (2013)

Page history last edited by Joe Redish 5 years, 8 months ago

Class content I 

1

 

An introduction to Physics 131:
Physics for Biology and Pre-Health-Care Majors

 

This introductory physics class and associated laboratories are designed so that they are directly relevant for biology majors, pre-meds, and other pre-health-care professionals.  We have settled on topics that are somewhat different from what other intro physics classes teach, and we use modern pedagogy in teaching these topics.  (However, note that students who took this class still did very well on a standard set of physics multiple choice questions, better on average than students in traditional physics classes).

 

Physicists tend to be convinced that physics is important in biology.  You may hear a statement like the following from a physics professor:


"Physics is important for biology since what we do in physics is try to understand the rules that govern how everything works.  Since biological organisms are part of 'everything', they are constrained by the rules of physics.  When you get to more advanced bio classes where you try to make sense of the mechanism of how things work, you’ll find the physics you've learned will be crucial."

 

However, not many biologists or doctors are convinced about the crucial importance of physics for understanding living systems. Many of them do not have particularly fond memories of a high-school physics course.  A key problem is that traditional physics courses taken by biologists are typically not designed particularly for biologists. Often they are “cut down” from courses designed for mechanical and electrical engineers. The set of physics topics in a traditional introductory physics course is not what is most relevant for future biologists. What makes matters worse is that the contexts in which the physics topics are introduced and reviewed is very different from the context of a living system: A frictionless cart sliding on a surface (a quintessential example of intro physics that we also will not avoid entirely) may be a good starting point for a mechanical engineer to consider cars with low-friction wheels.  But how do you get from the physics of such a simple system to the physics of a vesicle transported around inside a cell via myosin motor proteins? This question is never answered in traditional physics classes, but we will tackle it by covering additional physics relevant in this context (fluid drag, Brownian motion) in this class. 

 

As we tried to highlight in the above example, in this class both the topics we teach and the contexts in which we teach them are different from those of traditional intro physics. You will work through many examples of physics relevant to living systems. Our hope is that when you get to a professional level, either in biology research or in health care, you’ll find that the thinking tools you learn here will be valuable in your research or developing your diagnoses. Essentially, learning physics will enable you to see living systems from an additional perspective. Life is not simply a biochemical system or a signaling pathway; life also involves physical machinery constrained by the laws of physics. You will focus on physics at the convergence with biology, where physical, chemical, and biological principles all come into play. In addition, many of the instruments that you will be using to collect data will rely heavily on physics. To understand what you can reliably conclude from those instruments – and what their limitations are – you’ll need to understand some physics.

 

A central topic for this first semester is the concept of motion, and the difference between coherent, directed motion and the random motion that occurs at the molecular level will be a primary theme. For example, you will discover and explore random motion from all angles: you will learn the physics of random motion, explore how it leads to the principle of diffusion that is used in chemistry, and figure out how random motion and diffusion affect how cells communicate. Our understanding of how physical, chemical, and biological principles can converge is still in its infancy, but it is clear that a convergence of knowledge from the physical sciences, life sciences, and also engineering will be critical and enhance life on earth, from improving health care to securing our energy and food supply [ See e.g. The Third Revolution: The Convergence of the Life Sciences, Physical Sciences, and Engineering]

 

Physical laws apply to everything in the universe from quarks and atoms to galaxies. So, learning the physical laws that describe how an object moves, what forces it experiences, or what energy it has is important for all sciences and engineering. But how important are physical laws really for biology? You might ask why you should care about motion and forces, the main topics of the first semester. Do biological organisms really operate near their physical limits, or do genomics and proteomics and metabolomics rule? These questions have driven biophysics and quantitative biology research in the past decade with surprising results: Many characteristics of living things can be traced to physical constraints which provide a simple framework to think about the living world. You will see a number of examples in this class. 

 

The topics for this class have been carefully chosen as a result of extensive negotiation between physicists and biologists. We want this physics class to explicitly connect to what you are learning in all the scientific disciplines you have to study to learn to be a biologist or health-care professional -- biology, chemistry, and math.

 

  • The pre-requisites: In order to be able to put physics in a biological context, this course is situated to be taken after you have learned some bio, chem, and math.  We expect you to have taken the following:
    • Biology – some introduction to cellular biology, genetics, and evolution.
    • Chemistry – an introduction to basic chemistry including atoms, molecules, bonding, etc.
    • Math – basic calculus (derivatives and integrals) and an introduction to probability
  • The structure of the class: This class is set up to build on what has been learned over the past few decades about effective teaching methods. The main result of this research can be summarized in two principles:
    • What matters for your learning is not what the teacher does or what’s in the text but what you, the student, do with it.  What matters is what goes on in your head. We will create activities and environments that can help you effectively learn to use the the physics you are learning.
    • What matters for physics (and really for all of science) is not primarily learning facts or even protocols or procedures (though you will need to know both) but learning how to think with them and use them creatively. This means that both the activities and evaluations (quizzes, exams) in this class will not be simple recall, plug-and-chug, or find-the-keywords essays. Even on exams, we will be expecting you to think!  

 

Both the content and the structure of the class reflect these principles. As a result, in this class we

  • Include lots of biological examples and applications, at the nano, micro, and macro level (molecules, cells, and organisms).
  • Include lots of active “doing” things as opposed to passive “listening and reading” things.

 

Read carefully our webpages on the class mechanics, which includes a review of grading, so you don’t make wrong assumptions.  Your grade in this class is built up over the semester through lots of different activities – not just exams. (Exams are worth less than half your overall grade.) You don’t want to wake up halfway through and discover that you have already missed enough points that you can’t get an A!

 

In order to understand why we have chosen to set up the class the way we have, you may read our discussion of the nature of science in the sections below.

 

When you are done, we suggest you go on to the section:

 

There, we discuss what has been learned about your brain by cognitive- and neuro- scientists over the past half century and its powerful implications for the best ways to learn. The approach we take in this class is structured to try to optimize this kind of learning.

 

Joe Redish 7/4/11

Wolfgang Losert 8/25/2013

Ben Dreyfus 1/25/2015

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