Lesson 1: The Science of Physics

In this lesson, you will begin learning about the purpose of physics.

There is 1 learning objective for this lesson:

1. Describe the purpose of physics.

What is Physics?

Question:

Answer the following question based on your experience. You have multiple tries. Be sure to read the feedback based on the response you give.

What Physics is not…

• While it is true that we often use equations and solve problems in physics, this is not what physics is.
• Although physicists are obsessed with defining things and making sure everything has the right units, this is not what physics is.
• While it is true that we do use the scientific method, make discoveries, and sometimes use formulas, physics is not about discovering formulas.

What Physics is…

Physics attempts to model everything in the world around us. This modeling ranges in scale from things smaller than an atom to things larger than a solar system.

As physicists, we want to understand every detail of everything. We look for patterns everywhere in nature and try to figure out what it is that is causing the patterns we see. We attempt to extract the rules and laws that make everything in the universe work the way they do. 

In this course you will learn about the rules that govern how objects move and interact with one another. We sometimes refer to this as “Mechanics”. 

If you also take the second course in this sequence, you will learn further about motion and charges at the atomic and subatomic levels and come to a better understanding of what an atom actually is. You will also learn about the importance of charges in creating electricity and magnetism.

Making Assumptions

An important skill you will want to develop to succeed in your understanding of physics is that of identifying your assumptions. An unidentified assumptions ca be a road block to your progress and understanding. For instance, let’s say that I told you that I have two coins in my hand that add up to 30 cents and one of them is not a nickel. Could you determine which two coins I have in my hand?

If you say this is impossible, you likely assumed that neither coin could be a nickel. However the statement said that one coin was not a nickel. The one that was not a nickel was a quarter. 

Assumptions are not always bad but they do usually need to be identified. 

Let’s say that I ask you to measure the height of the DuBois library here on campus using nothing but a tape measure. How would you go about getting a decent measurement? 

If you went into the stairwell of the building it would be challenging, but not impossible to measure the height of one floor. After doing so, you could make the assumption that each floor of the building has the same height. Then by knowing the number of floors in the building it would be a simple calculation to determine the height of the building. 

Measurement and Precision

You may argue, however, that the calculation would not be very precise. You would be correct since this is not the most precise way we could measure the building. But our calculation would be a decent approximation. 

So, then, why do we bother taking a measurement that is not the most precise? There can be several reasons why you may want to do so. Sometimes the information we need to know does not need to be very precise. Let’s say you measure a certain portion of a room to see if the new desk you want to purchase will fit. If you use a tape measure and see that it is about 5 feet by 10 feet and the desk you like is 2 feet by 4 feet, is there any need to be more precise? 

Sometimes it isn’t worth the time or cost to get the most precise measurement. How might one go about making the most precise measurement of the average height of every human currently alive? You would have to organize quite the campaign to get that done. It’s simply not worth the time or money to do and so we look for a quicker and cheaper way to make the measurement. 

Sometimes there is no other option. Ongoing experiments attempt to precisely measure aspects of subatomic particles which can’t be seen even with the most powerful electron microscopes. In addition, many of these particles come into and out of existence in a fraction of a second. This means that we have to find other ways to make these measurements. This is what much of current physics research is doing today. 

At Fermilab, one of the experiments is attempting to improve upon the measurement of the muon magnetic moment anomaly. Some of the physics faculty and graduate students at UMass are a part of this team which is made up of hundreds of physicists from 20+ countries and 80+ institutions. 

This is the science of physics – finding ways to measure the immeasurable, explain the unexplainable, and describe the indescribable. 

Physics is about simplification. We want to break down the universe into its most basic parts – the parts that make up everything. We know that atoms make up matter and protons, neutrons, and electrons make up atoms, but what make up protons, neutrons, and electrons? And what make up those things? What are the most elementary particles that make up everything? 

In order to find the answers to problems like these, we have to simplify things. A key way we do so is by creating models. For instance, since we can’t see an atom we have to make a model to explain what we think is going on inside it based on the effects that atoms create. In fact, many models have been created to try and explain the atom. When we encounter things that we can’t see or are difficult to measure, it is necessary to simplify the situation with a model. You will study many models in this course.