1.1 Physics: An Introduction

Take a look at the image.

There are billions of individual stars, huge clouds of gas, and dust in the image.
There are bright blue spots in the background.
At 2.5 million light years away from the Earth, this galaxy is the closest one to our own.
The stars and planets that make up Andromeda might seem far away from the everyday lives of most people.
There are forces that hold together the universe.
The same forces that cause Andromeda to act as it does are the same ones that cause us on Earth to raise the walls for a new home or send a rocket into space.
The stars of Andromeda are caused by the same gravity that causes water to flow over hydroelectric dams here on Earth.
Look up at the stars tonight.
The forces out there are the same as the ones on Earth.
You can gain a better understanding of the universe through a study of physics.

Think about all of the technological devices you use on a regular basis.

Computers, smart phones, gps systems, mp3 players, and satellite radio are some of the things that might come to mind.
Think about the most exciting modern technologies that you have heard about, such as trains that levitate above tracks, "invisibility cloaks" that bend light around them, and tiny robots that fight cancer.
The principles of physics are used in all of these advances.
Professionals such as engineers, pilots, physicians, physical therapists, electricians, and computer programmers apply physics concepts in their daily work.
A pilot and a physical therapist need to understand how wind forces affect a flight path.
This text will show you how physics principles are applied in a wide range of careers.

You will begin to explore the history of the formal study of physics, beginning with natural philosophy and the ancient Greeks, and ending with a review of the laws of physics that bear his name.

You will be introduced to the standards scientists use when they study physical quantities and the system of measurements most of the scientific community uses to communicate in a single mathematical language.
You will study the limits of our ability to be accurate and precise, as well as the reasons scientists go to lengths to be as clear as possible regarding their own limitations.

The laws of physics govern the flight formations of migratory birds.

There is a lot of detail in the physical universe.

Every day, we look at many objects and phenomena.
The curiosity of the human race has led us to explore and catalog a lot of information.
From the flight of birds to the colors of flowers, from lightning to gravity, from quarks to clusters of galaxies, from the flow of time to the mystery of the creation of the universe, we have asked questions and assembled huge array of facts.
We have found that a small set of physical laws can explain what we see.
Humans make generalizations and seek order.
Nature exhibits order and simplicity that we value.

Science and physics are enjoyable to study because of the underlying order of nature.

The energy in both of them can be converted to other forms.
Food calories, batteries, heat, light, and watch springs are all related to the law of conserve energy.
Understanding the law makes it easier to understand the different forms of energy taken.

The basic simplicity of nature and the unifying aspect of physical laws form the underlying themes of this text.

The most important topics in physics will be studied when you learn to apply these laws.
You will gain analytical abilities that will allow you to apply these laws far beyond the scope of what can be included in a single book.
Analytical skills will help you to think critically in any professional career you choose to pursue, and they will also help you to excel academically.
The realm of physics, some applications of physics, and more precisely what constitutes a physical law are discussed in this module.

The theories and laws that make up science are the general truths of nature as well as the body of knowledge they encompass.

Scientists are constantly trying to improve the expression of the laws that describe it.

The realm of physics is defined by the concern for describing nature's basic phenomena.

The function of everything around us is described by physics.

Everything around you can be described by the laws of physics.

Consider a smart phone.

The various circuits inside the device interact with electricity.
When building a smart phone, engineers use this knowledge to pick the right materials and circuit layout.
Next, look at a gps system.
The relationship between the speed of an object, the distance it travels, and the time it takes to travel that distance is described by physics.
The travel time from one location to another is determined by the physics equations used in the gps device.

The Apple "iPhone" is a smart phone.

The circuits of this device are described in physics.
Engineers use their knowledge of physics to build an Apple product that consumers will enjoy.
The gps function is a specific feature of the iPhone.
The driving time between two locations on a map is determined by the use of physics equations.
You don't need to be a scientist to use physics.
In everyday situations and nonscientific professions, knowledge of physics is useful.
It can help you understand how microwave ovens work and why metals should not be put into them.
You can rationally evaluate the dangers of radiation with the help of physics.
It explains why a white roof helps keep the inside of a house cool and why a black car radiator helps remove heat from a car engine.
When you think about basic physics, the operation of a car's ignition system and the transmission of electrical signals through our body's nervous system are easy to understand.

The foundation of many important disciplines is physics.

Since it deals with the interactions of atoms and molecules, chemistry is related to atomic and molecular physics.
Applied physics is the most common branch of engineering.
In architecture, physics is involved in acoustics, heating, lighting, and cooling of buildings.
Parts of geology rely on physics such as radioactive dating of rocks.
Some disciplines, such as biophysics and geophysics, are related to physics.

There are many applications of physics in the biological sciences.

It helps to describe the properties of cell walls and cell membranes.
The heat, work, and power associated with the human body can be explained on the macroscopic level.
Medical diagnostics include x-rays, magnetic resonance image (MRI), and blood flow measurement.
For example, cancer uses ionizing radiation.
Music, the eye, and lasers can all be explained by physics.

It's not necessary to study all applications of physics.

Knowledge of the basic laws of physics and a skill in analytical methods are the most useful.
The study of physics can help you solve problems.

The study of physics makes other sciences easier to understand and physics has retained the most basic aspects of science.

Understanding how common appliances work is aided by the laws of physics.

The laws of physics can help us understand why it is dangerous to place metal objects in a microwave oven.
The applications of physics are more in common than you might think.
Microwave ovens use microwaves to cook food.
The exact location of tumors can be determined by using an image of the brain from magnetic resonance imagery.

The properties of cell walls in plant cells are described by physics, chemistry, and biology.

The structure and function of animal cells can be found in the Membranes.
The firing of nerve cells is one of the most fundamental properties of life.
The disciplines of biology, chemistry, and physics help us understand animal cells.
The laws of nature are concise descriptions of the universe around us, they are human statements of the underlying laws or rules that all natural processes follow.
Humans can't change the laws of the universe.
Their discovery is a very human endeavor, with all the elements of mystery, imagination, struggle, triumph, and disappointment inherent in any creative effort.

He was the exchequer of the Royal Mint after leaving his academic post.

He invented reeding on the edge of coins to prevent people from using silver to make money.

She is the only person to have won both physics and chemistry prizes.

One of her daughters won a prize.

We all are curious.

We look around, make generalizations, and try to understand what we see, for example, we look up and wonder if one type of cloud signals an oncoming storm.
We become more organized and formal in collecting and analyzing data as we become more serious about exploring nature.
We attempt greater precision, perform controlled experiments, and write down ideas about how the data may be organized and unified.
We collect data and analyze it to come up with models, theories, and laws based on the results of the experiments.

The model is only accurate in limited situations.

An example is the planetary model of the atom in which electrons are pictured as being in the nucleus.
The mental image helps explain the observations we can make, such as the emission of light from hot gases.
Physicists use models for a lot of things.
Physicists can use models to analyze a scenario and perform a calculation, or they can use models to represent a situation in a computer simulation.
Some theories use models to help visualize phenomena, while others don't.

The kinetic theory of gases is a model in which a gas is viewed as being composed of atoms and Molecules.

Atoms and Molecules are too small to be seen directly with our senses, so we picture them to understand what our instruments tell us about the behavior of gases.

A single mathematical equation can be used to express a law.

Laws and theories are both scientific statements that are supported by scientific evidence.
The designation law is reserved for a concise and general statement that describes phenomena in nature, such as the law that energy is conserved during any process, or the second law of motion, which relates force, mass, and acceleration by the simple equation.
A less concise statement of observed phenomena is a theory.
The Theory of Evolution can't be expressed concisely enough to be considered a law.
A theory is more complex and dynamic than a law.
A theory explains a group of phenomena while a law describes a single action.
A theory is the end result of the process that formed the foundation of the scientific method.

Less broadly applicable statements are usually called principles, but the distinction between laws and principles is not carefully made.

The nucleus is shown in the planetary model of the atom.

We can't see the atom with our eyes because it's too small, so we use a drawing to create a mental image of it.

Scientists use models, theories, and laws to analyze the data they have collected.

After a model, theory, or law is developed, it points scientists toward new discoveries.

The existence of objects or phenomena is implied in the models, theories, and laws we create.

These predictions are testaments to the power of science.
Scientists are able to make spectacular predictions because of the underlying order in the universe.
If experiment doesn't verify our predictions, the theory or law is wrong, no matter how elegant or convenient it is.
Laws can never be known with absolute certainty because it is impossible to perform every imaginable experiment in order to confirm a law.
Physicists assume that all scientific laws and theories are valid until a counterexample is observed.
The law must be changed or overthrown if a good-quality, verifiable experiment conflicts with it.

The study of science in general and physics is very similar to the exploration of the ocean.

The beauty of the physical universe is made more beautiful by the insights gained from discoveries, models, theories, and laws.

The process begins with an observation and a question.

The scientist usually does some research about the topic and then comes up with a hypothesis.

The scientist draws a conclusion after analyzing the results of the experiment.

The scientific method can be applied to many situations that are not limited to science, and can be modified to suit the situation.

Consider an example.

If you try to turn on your car, it won't start.
You can use a scientific method to answer the question.
You can do some research to figure out why the car won't start.
You may think that the car is not starting because it has no oil.
You can check the oil level by opening the hood of the car.
You conclude that the oil level is not contributing to your car issue when you observe that the oil is at an acceptable level.
You can try a new hypothesis and then repeat the process again.

It wasn't always a separate and distinct discipline.

It is connected to other sciences.
The Greek word for physics is nature.
Natural philosophy encompassed astronomy, biology, chemistry, physics, mathematics, and medicine from ancient times through the Renaissance.
Over the last few centuries, the growth of knowledge has resulted in ever-increasing specialization and branching of natural philosophy into separate fields, with physics retaining the most basic aspects.
It was transformed into modern physics by revolutionary discoveries at the beginning of the 20th century.

Natural philosophy has evolved into more specialized disciplines as a result of the contributions of some of the greatest minds in history.

Matter must be moving at less than 1% of the speed of light, the objects dealt with must be large enough to be seen with a microscope, and only weak fields, such as the Earth's, can be involved.

Classical physics seems reasonable because humans live under such circumstances.
This is the reason why models are so useful in modern physics.
We can relate to models in human terms and imagine what they would look like if they were too small to see.
Although we have never seen an atom with our eyes, we can picture it in our minds and understand its properties.
New tools allow us to see phenomena we can't see.
In the last few years, new equipment has allowed us to see the atom.

The laws of classical physics can be applied if the matter is moving at less than 1% of the speed of light, the objects are large enough to be seen with a microscope, and the field generated by the matter is weak.

Scientists can see individual atoms using a scanning tunneling microscope.

Modern physics has made some of the most amazing advances in science.

Changes in technology, society, and our view of the universe have resulted from many of the laws of classical physics being modified or rejected.
Modern physics is filled with fascinating objects beyond our normal experiences, but it has an advantage over science fiction that is very real.
Classical physics gives an accurate description of the universe under a wide range of everyday circumstances, and knowledge of classical physics is necessary to understand modern physics.