Lecture 2 >>

Practice Activities


NASA’s metric confusion caused Mars orbiter loss – This CNN article discusses how not using the correct units on calculations led to the destruction of a $125 million Mars orbiter. Units matter!

What is a law in science? (PDF) – This article explains the difference between a scientific theory and a law.

Video Transcript

Hello there! Welcome to lecture one: about science!

This video will explain how we will interpret and come to understand physics in this class. This lecture focuses on the terminology, processes, and procedures that will form the foundation for a solid understanding of conceptual physics.

Each of the following concepts will be discussed in this video: what is science, scientific terminology, the scientific method, science and technology, the scientific mind, and the mathematics of physics.

What is science?

Science is the systematic pursuit of knowledge that comes about through asking questions, making careful observations, and carrying out experiments about how the universe works. Science has helped us to answer questions as diverse as how large our planet is, to how old the universe is, to what matter is made out of, and so much more.

The scientific method, which we’ll cover in more detail in a few minutes, is the process by which scientists come to solve problems. It all starts with asking a question. What is light? What elements are stars made of? How far away is the nearest solar system to ours?

Science does a really great job answering questions we have that ask what and how. How big is our planet? That is a question we can use the scientific method to solve. What is all matter made of? That is another question we can solve using scientific principles.

Unfortunately, science is not always well suited to answering questions that ask why. Why does our universe exist? Why do humans have consciousness? These are really great questions. Science may help us inch closer to an answer, but likely will not be able to provide any definitive answers. In these cases, philosophy and religion can help us to interpret and understand these deep questions.

Science is best used to answer questions that can be tested and validated experimentally. If I state that the Earth has a mass of 6 times ten to the 24 kilograms, that statement is only a hypothesis until it is experimentally validated by other scientists. If my hypothesis is verified by many other scientists, then it becomes a fact.

Experiments that seem to disprove a well-known fact can lead to revolutions in our understanding of the physical world. Up until about the late 19th century, it was commonly accepted that light was a wave. All of our observations and experiments verified that light acted exactly like a wave. However, the photoelectric effect and its explanations produced a profound discovery: that light also acts like a particle! This discovery helped usher along the newly formed quantum physics, and has led to technology such as light sensing photomultiplier tubes and some of the sensors used in digital cameras and night vision goggles.

However, experiments must be repeatable and verified by more than one scientist. Experimental errors, or misunderstanding the results of an experiment, can lead to setbacks in science. Whether these mistakes are malicious or not, scientists must remain skeptical of experimental evidence until it is verified by others.

From all of this, we can conclude that scientists must be not only open-minded and curious, but also skeptical and fastidious as well! We’ll talk more about the scientific mind in a few minutes.

Scientific terminology

One thing you may notice in this class is my use of, and expectation that you use, proper scientific terminology. It is important that I convey information to you that you can correctly interpret and understand. This is important not only in the physical sciences, but also in engineering and technology fields as well.

Sometimes you may find that there is a disconnect between colloquial or casual use of a term, and the physics use of a term. I will do my best to point out these cases when they occur and give you a note of caution in using them in class!

At this point, I’m going to define a few terms that will be used throughout the semester. When I say Newton’s law of universal gravitation, what is meant by the word law? How about the word theory when I talk about the theory of relativity?

First, let’s define a hypothesis. A hypothesis is a descriptive statement about how the world works, based on observations. This hypothesis can be tested to determine whether or not it is valid. An example of a hypothesis would be for me to say “the sun is more massive than the Earth.” Either myself or other scientists could devise experiments to test whether or not my hypothesis is true.

A theory is an explanation of how the universe works that is supported by multiple, repeated experiments. A good theory makes predictions that can be verified as true or false by experiment. If a theory offers no predictions that can be proven or disproven by experimental observations, then we have no way to determine whether or not it is valid.

There are many theories that explain our physical world. Plate tectonics, special relativity, and quantum mechanics are just three examples. These three theories have held up to much scientific rigor and scrutiny over many years. To dismiss them as “just a theory” would be to discount the vast amount of evidence that points to their accuracy. We may revise and edit theories as we learn more about the universe.

A scientific law is a statement that explains phenomena that we observe. These laws can be used to predict the behavior of objects. Many times, laws use mathematical equations to explain and quantify these behaviors and phenomena.

Newton’s law of universal gravitation, which we’ll discuss in lecture nine, explains the motion of objects such as planets, stars, and satellites. We use an equation to quantify the degree of gravitational attraction between different objects: for example, to determine the gravitational force between myself and the planet Earth.

The scientific method

Now that we’ve discussed what science is, and defined a few key terms that we frequently use when discussing it – how do we actually DO science? How can we go from an observation to an understanding of how the universe works?

The scientific method that you may have learned about in school is usually presented as a straightforward set of tasks that, when completed, will result in an updated understanding of our physical world. That is not always the case!

Regardless of the set of steps we go through in our pursuit of science, the scientific method always starts with a question, or an observation that leads to a question. Why is the sky blue? What is an atom made of? How fast is light?

After asking our question, we then conduct background research. Has this question already been answered? If so, do we agree with the results? If the question has not already been answered, are other scientists working on answering this question? If not, are there similar questions that have been asked that might give us an idea of how to formulate a hypothesis or conduct an experiment?

Then we form a hypothesis. This can be an educated guess, or a more reasoned statement that attempts to answer our question. Our hypothesis should be testable using experimental methods. We may find ourselves reformulating or revising our hypothesis as we go through the next few steps in the scientific method.

Determining how to test a hypothesis can be a challenge. Some experiments may be simple and straightforward to conduct. Others may require expensive equipment or a specialized research laboratory to conduct.

Once the experimental setup and testing has been devised, we then conduct the experiment. This may require collaboration with other scientists. When I was a graduate student in engineering, I frequently worked with the chemistry department, as they had the experimental setup that I needed to collect data from the samples I created. On a larger scale, a scientist may have a hypothesis that can be tested by using a particle collider, say, the one at Argonne National Laboratory, or at CERN.

After performing the experiment, the data that was generated by the experiment must be analyzed. If we’re lucky, the data points to a clear conclusion that supports our hypothesis. Sometimes the data may be vague or unclear, which may require us to modify the experiment to collect more data. Maybe the data disproves our hypothesis! Some very important experiments have disproved incorrect scientific hypotheses. Famously, the Michaelson-Morley experiment in 1887 disproved the existence of some type of medium that permeates through all of space. We now know that the vacuum of space is indeed a vacuum.

What if, instead of having clear data after our experiment, we got weird results instead? We need to determine if we made an experimental error, or perhaps there was a problem with our hypothesis. We troubleshoot the problem – sometimes by conducting additional research – and then either reformulate the hypothesis, or create a new experiment to gather more data.

After we’ve completed our experiment, we communicate our results to the scientific community. Frequently this will be through a peer-reviewed scientific publication. Peer review means that other scientists in our field read through our work to double check our experimental procedures and data analysis. We may also decide to present our work to others at scientific conferences. These conferences can lead to new questions being asked, and collaborations formed to help answer them!

Once we’ve concluded our experiment, we can create technology based on our results. This does not always happen right away, sometimes it may take years to create technology based on scientific results.

Many times, the introduction of a new technology may generate new problems that require solutions using the scientific method. The internal-combustion engine is a wonderful technology… but it leads to greenhouse gas emissions. Nuclear power provides lots of energy to our homes, but generates hazardous waste. Even technologies such as computers, smart phones, and the Internet have led to issues involving the widespread propagation of misinformation.

Sometimes, our knowledge of the universe is expanded upon by observations that occur serendipitously or by accident. The heating properties of microwaves were discovered when they melted a chocolate bar in the pocket of an engineer. That engineer then used the scientific method to determine how to turn this discovery into a technology that many people have in their homes today: the microwave oven.

Science and technology

Science, as mentioned, is the pursuit of knowledge about how the universe works. Physics is a branch of science that focuses on the fundamentals of the workings of our universe. While physics has a lot of overlapping interests with other fields such as chemistry, biology, and even math and materials science, we consider physics to be the fundamental science, as it deals with the natural world without focusing on any one particular topic.

On the other hand, engineering is the application of the science that is generated in physics, chemistry, biology, and other fields into the creation of new technology.

My bachelors, masters, and PhD degrees are in electrical engineering. I am an engineer. This means that I learned about physics, especially electricity and magnetism. This is science: explaining how the universe works, specifically as it pertains to electricity and electronics. I also took a lot of math classes such as calculus and differential equations to quantify the topics I learned about. But then I also learned about and focused on the application of those scientific and mathematical principles to solving problems and creating new technology.

When I teach physics, I give students the knowledge of how the world works. That’s fascinating and powerful stuff! When I teach engineering, which I also teach at the College of DuPage, I help students turn that scientific knowledge into an ability to apply it in new and unique ways.

When you think about technology, what is the first thing that comes to mind? Computers? Electric vehicles? Spaceships and satellites? Those are all great examples of technology. Technology is what we get when we use scientific principles to solve problems. There are a lot of examples of technologies all around us: some of them more high tech than others. Everything from the homes we live in, to the clothes we wear, to things as mundane as pencils and paper, are technology. Over time, the technology improves when we learn more about the science behind them.

At times, science very quickly leads to technological innovations. Semiconductors were found to emit light, and this led to the invention of the light-emitting diode: or LED. These days, LED lighting has become affordable and practical enough for most of us to have LED lighting in our homes, flashlights, and even smart phones.

Other times, science may take years or even decades to evolve into practical technology. It took several decades between Einstein’s formulation of the theory of relativity and a technology that uses it: GPS. Relativity is required to coordinate the timing between moving satellites and the humans on the Earth’s surface who use them to determine their position on the planet.

The scientific mind

There are many properties that a good scientist should possess. First and foremost: a scientist should be curious! Many people in science and engineering fields have been excited about learning how and why things work. This drive to learn more about the universe helps us to come up with new questions to solve, and new techniques that we can use to solve them.

Scientists should also be open-minded about how the universe works. One of the difficulties in teaching a physics class is that many students come in to the class with many misconceptions about physics. And that’s okay, you’re still learning – but be prepared to learn that the universe may work differently from how you currently think it does. It’s possible that you just don’t have all of the information you need to understand the full picture of how our universe works. This happens all the time in science!

On the other hand, a good scientist remains skeptical of scientific data until it has been held up to rigorous experimentation and scrutiny. You should trust, but verify, that information is correct. Hold things to a high standard of rigor. Do not believe what people in authority tell you just because they are in a position of authority: demand experimental validation and verification! Just because I am a professor who has a PhD does not automatically make me correct. However, I will never knowingly mislead you at any time in this class. But if you’re ever confused: ask questions!

Scientists should also have integrity. They should not falsify their experimental data or observations. They repeat their experiments to confirm that they are reproducible. Good scientists should never mislead people about their discoveries or their impacts. Unfortunately, there have been many scientists throughout history who have purposefully mislead the public about their results, or who have fabricated information to boost their careers.

Not only should scientists be careful in how they present their data, they should also think through the possible repercussions of their work. Being able to split the atom was an outstanding scientific innovation, but it also led to the creation of atomic bombs. It is irresponsible to society to disconnect science from its possible uses and outcomes.

When people misuse scientific phrases and terminology – usually to mislead others into purchasing a product that sounds “high tech” – we call this pseudoscience. This is scientific-sounding jargon that is usually meant to get you to part with your money to purchase something that has not been verified to work using the scientific method. Or, pseudoscience can relate to an idea about how the world works. Unfortunately, there are individuals and companies that exploit people who lack the scientific literacy to see through their claims.

To identify pseudoscience, ask a few questions: Does the idea or product make use of vague, exaggerated, or unverifiable claims? Is the data behind the idea or product open and has it been tested by other scientists? Does the idea or product ignore compelling scientific evidence? Does the person or people behind the idea or product attempt to suppress others who dissent or show evidence to the contrary?

For example, astrology, the belief that we can make predictions about our lives based on the positions and movements of planets and other celestial bodies, has no basis in science. No evidence has been found to support astrology, and all falsifiable predictions made with astrological methods have been falsified using the scientific method.

Unfortunately, there are many areas of pseudoscience in areas ranging from physics to medicine, history, and psychology and sociology. At best, these products and ideas cost us money. At worst, they are harmful, toxic, perpetuate racism, and cause other societal problems.

The mathematics of physics

Throughout this class, we will want to quantify our discussions of physical phenomena. This means we want to be able to express different values numerically. We use math to put numbers to our discussions.

Each physical quantity that we discuss will have a symbol associated with it. Every time we learn something new, that symbol will be defined so that you know what it means. For example: mass has a symbol of the lowercase letter m. Temperature has a symbol of the capital letter T.

Sometimes the symbols use the English alphabet. Sometimes they will use Greek letters. For example, the concept of wavelength tells us the distance between two identical points on a wave. The symbol for wavelength is the lowercase Greek letter lambda.

Many quantities just convey a numerical quantity: a value or a strength. We call these quantities scalars. Sometimes a quantity needs to express both a strength and a direction. These quantities are known as vectors. Vectors have an arrow above the symbol, or are expressed using a bold font. We will talk about vectors in more detail in the next few lectures.

All this is to say that understanding that symbols relate to actual physical quantities is important. Different physical quantities relate to each other by means of mathematical equations. These equations are frequently derived from a physical law, for example, Newton’s laws of motion. We will learn about each equation as it is defined in our lectures, and what that equation tells us about the physical world.

Sometimes we may find that a few physical quantities use the same symbol. Specific heat capacity is defined by the lowercase letter c. But so is the speed of light! Capital V can stand for either volume or voltage. How do we know which is which? Just as we learned the meaning of this word: bat. Do I mean the animal? Do I mean the stick you use to hit a baseball? It all depends on context. When we see a symbol in equation, we look at the other symbols nearby to help us determine the meaning, just as we read other words in a sentence to determine the meaning of the word bat.

If all of this seems overwhelming right now, that’s okay. Just as you did not learn to speak or read the English language overnight, learning the mathematics of physics is also a process. Be patient with yourself, but also know that all things improve with practice. Use your equation sheet to help you solve homework problems, and use that practice to improve your skills.

One last thing – all of the physical quantities we use in this class are not only defined by a symbol, but also have units that we use to express those values. One great example is temperature. Temperature has a symbol of the capital letter T. But if I tell you that the temperature is 10, that’s not enough information to determine what to wear when you go outside. I also need to tell you the units!

In physics, we will use SI units, known as the international system of units. These units are internationally used in physics and engineering. They differ from the English units you may be used to. We use meters as the SI unit of distance; not feet or inches. We use kilograms as the SI unit of mass; not pounds or slugs. Whenever possible, I will do my best to give you some context for these units, as they may be new for you.

Why are units important? Just as I mentioned that scientists need to use precision in our language and terminology, so do we need to use precision in our quantities. It would be inconvenient for me to tell you that it’s 10 degrees outside, so you decide to put on several layers of sweaters and jackets, only to realize that it’s 10 degrees Celsius outside, not 10 degrees Fahrenheit! That example may not be a big deal, but incorrect units used in dosing medication or medical therapies could have a fatal outcome. In 1999, an orbiter was sent to mars. Rather than landing on the surface, it crashed, creating a very expensive crater on the surface of the red planet. The crash occurred because some of the team members used English units (pounds), while other members used SI units (Newtons). Understand that I’m not just being picky when I talk about units. These things matter! Get into the habit of using units all the time in your practice and your homework.

Thanks for taking the time to learn about science. Until next time, stay well.