2023/7/19 11:39
What is Physics? - Definition, History & Branches - Video & Lesson Transcript | Study.com
What is Physics? - Definition, History & Branches
Contributors: Mattye Brecht, Elizabeth Friedl
What is physics? Is physics science? Learn the definition of physics and the relation between physics and
science. See the various branches of physics and learn their importance.
Table of Contents
 What is Physics?
 Branches of Physics
 Importance of Physics
 Lesson Summary
What is Physics?
The definition of physics is the study of the physical plane of matter, motion, force, and energy.
The root word of physics is Phys- and is Greek for "nature" and "natural order." Physics itself is
studying the natural world and the interactions between objects and energy in any given
environment.
In ancient Greece, early scientists did not have anything more than their senses to help them
study the world around them. These scientists often studied their environment through touch,
taste, smell, sight, and sound. During the 17th century, people like Galileo, Copernicus, and
Newton revolutionized science with breakthroughs of physics through the laws of gravity, the
sun-centered theory, and the discovery of atoms. With modern technology and advances in the
scientific method, physics incorporates things that are not observable to the naked eye.
Is Physics Science?
Is physics science? This question may seem obvious, but is physics considered science or art?
Science is defined as a compilation of observations, predictions, and organizational methods of
testing the universe. Art is an individual's expression of their experiences through creative skill.
The answer is yes; physics is a science. Since physics concerns itself with observations and
testable predictions about the physical universe and not someone's opinion of said universe, it
is most definitely a science.
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Branches of Physics
The physical universe has many moving parts and is not simply what is observed through the
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naked eye. Physics is also how the most prominent objects interact with the smallest and
everything in between. Since physics is such a broad subject, it has to be broken into smaller
categories or disciplines, also known as fields of study.
There are three main categories of modern physical study:
1. Classical physics covers electromagnetism, classical mechanics, thermodynamics, and statistical
mechanics. Classic physics provides action and reaction, showing how objects acting in a system will
interact with other objects in that same system.
2. Relativity has two types of study; there is general and specific relativity. General relativity deals with
how the law of gravity interacts with objects; this has a significant bearing in astrophysics and
astronomy. Special relativity concerns how objects interact in a vacuum or are devoid of gravity.
3. Quantum physics is the most recent course of study in physics. Here, scientists study quantum
mechanics, quantum statistics, quantum electrodynamics, and quantum field theory. This branch deals
primarily with objects at an atomic and subatomic level. It answers questions like, "what makes a
proton different from a neutron?"
Mechanics
The study of mechanics is both broad and specific. Broadly, mechanics study objects, their
motion, energy, and how they interact with other objects and energy. There are two subbranches of mechanics, quantum mechanics and classical mechanics.
Quantum mechanics, studies how atom and subatomic particles act and react with one another;
similar to how the atom is held together, what happens if two atoms collide? What makes up the atomic
particles; how and why do two atoms bond; what holds together millions of atoms into a complex
compound?
Classical mechanics follows the same principles as quantum, at a much larger scale. Examples of
classical mechanics would be predicting planetary orbits or the path of a bullet, black holes, friction
between a car tire and the road, why water has surface tension, or the arc of a baseball as it is thrown
across home plate.
Mechanics can explain a minor interaction, like why an electron is attracted to a proton, and the
most significant interaction, like why the earth orbits the sun.
Optics
One of our two most important senses is that of sight. In physics, the study of light and its
properties is called optics.
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One reason light is a fascinating study subject is that it contains the properties of a wave and
particles. Additionally, electromagnetic waves make up light, meaning it has properties of
electricity and magnetism and does not need a medium to move.
There are several different types of light:
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What is Physics? - Definition, History & Branches - Video & Lesson Transcript | Study.com
Visible
Ultraviolet
Infrared
X-ray
Radio Waves
Gamma Rays
Prisms take visible light and split it into different wavelengths
Thermodynamics
Similar to mechanics, thermodynamics covers a broad range of studies. Thermo-heat and
dynamics-relationships is the study of relationships between heat and other forms of energy.
For example, due to oceans covering a significant part of Earth, Earth does not experience large
swings in overall temperature because water holds in heat better than dirt and keeps life going
on this planet. Fewer oceans would result in temperatures between night and day, summer and
winter being too large to sustain many life forms. The relationship between heat held in water
versus heat given up by water is vital to study and understand.
There are three laws of thermodynamics, which govern the interaction between heat and
energy in a system:
1. First Law: Energy can change its form, but not amount.
2. Second Law: Entropy of any system ascends towards chaos or the loss of useable energy.
3. Third Law: Entropy is at its smallest when the temperature of a system approaches absolute zero.
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Electromagnetism
Electromagnetism is the manipulation of electric currents and fields along with magnetic fields.
Electricity and magnetism require a medium or an object to work through Elements like gold
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Electricity and magnetism require a medium or an object to work through. Elements like gold
and copper are good conductors. These conductors allow the flow of electricity due to their
atomic layout. Not only are there good conductors, but there are also good insulators. Silicon is
a good insulator; it does not allow the passage of energy easily.
Michael Faraday, an English scientist from the 19th century, hypothesized that electricity and
magnetism ran in lines of force. He observed iron filings lining up end to end on a magnet,
which supported his theory. Faraday also created a magnet using electricity.
Electromagnet showing magnetic and electrical fields
Acoustic
The branch of physics that studies the properties of sound is called acoustics. Sound is created
by mechanical vibrations or movement within all forms of matter. However, while acoustics is a
part of physics, it permeates many different aspects of study, whether science or art.
For example, biologists study hearing, as it is one of the most important senses, and geologists
study earthquakes due to their substantial seismic and acoustic waves. Additionally, sound
dampening is an important property to consider in engineering, and music is an art that is
hugely dependent on sound and vibrations.
Relativity
Albert Einstein is probably the most famous of modern scientists. One of Einstein's most
important contributions to science is the theory of relativity, both general and special. He
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theorized that forces, like gravity, can be experienced differently by objects moving at different
speeds. Gravity itself is a distortion of space and time. Time does not move in a straight line as
previously believed; someone who is moving at the speed of light will age differently than
someone moving much more slowly. The phenomenon is only relative to the observer.
Importance of Physics
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Physics is the oldest science and can be concluded as the most important. As observers and
participants in life, humans need to understand and explain their world, which will allow for the
understanding of the environment, leading to the manipulation of that environment. Due to
physics, things like electricity, magnetism, temperature, relativity, the atom have been studied
and put into practical use; household items such as water heaters, lights, and plumbing can all
be attributed to a discovery in the realm of physics.
Since physics is essentially the study of the whole environment, it has led to advances in other
areas of science as well. For example, chemistry and thermodynamics study go hand in hand;
acoustics is essential in biology and sociology to understand how humans interact; art and
music depend on the artist or musician's innate understanding of light and sound.
Lesson Summary
Physics is the scientific study of nature, focusing on the physical plane of motion, force, and
energy and comes from the root Phys, Greek for "nature" and "natural order."
There are several branches of physics:
Mechanics: The study of bodies in motion
Optics: The study of light and its properties
Thermodynamics: The energy of a system and how it changes
Electromagnetism: A combination of opposite charges and the energy fields they create
Acoustical: The study of sound and the apparatuses and vibrations it causes
Relativity: General relativity is with gravity, and specific relativity is without gravity; space and time
are different for different observers
Physics is the oldest and most important aspect of science. It bleeds into multiple areas, like
music, art, and biology, ultimately setting the framework for other areas of study.
Video Transcript
What Is Physics?
Most people hear the word 'physics' and run for cover. But it's not just for rocket scientists! You
are surrounded by physics all the time, and whether you realize it or not, you use physics every
day. Physics, the study of matter and energy, is an ancient and broad field of science.
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The word 'physics' comes from the Greek 'knowledge of nature,' and in general, the field aims to
analyze and understand the natural phenomena of the universe.
One thing that may come to mind when you think of physics is the many scientific laws, which
are statements describing phenomena that have been repeatedly tested and confirmed. This is
actually an important part of physics. Physicists perform and repeat experiments, sometimes ad
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What is Physics? - Definition, History & Branches - Video & Lesson Transcript | Study.com
nauseam, to formulate these laws and explain how our universe works. These laws (such as
gravity and Newton's laws of motion) are so thoroughly tested that they are accepted as 'truths,'
and they can be used to help us predict how other things will behave.
Because physics explains natural phenomena in the universe, it's often considered to be the
most fundamental science. It provides a basis for all other sciences - without physics, you
couldn't have biology, chemistry, or anything else!
Physics Is Old
Physics has been around for a long, long time. We consider the Ancient Greeks to be the
'founders' of early physics, as they pushed for a better understanding of the natural world
around them. This includes some major players you are likely familiar with, like Socrates, Plato,
and Aristotle.
Modern physics came centuries later, with folks like Copernicus, Galileo, and Newton during the
15- and 1600s. There were many critical scientific breakthroughs during this time as people
discovered more and more about our universe.
In fact, much of the knowledge we take for granted was discovered during this Scientific
Revolution. For example, Copernicus was the first to demonstrate that the earth revolves
around the sun, not the other way around.
Galileo described many fundamental physical concepts, but he also made many astronomical
discoveries, such as sunspots and planetary satellites, by perfecting the telescope.
Physics certainly wouldn't be the same without Isaac Newton, who you will no doubt learn much
about in your physics studies. He is probably most famous for his three laws of motion and the
law of universal gravitation. Newton is also credited with inventing calculus, though you may or
may not agree with that being a good thing!
Disciplines of Physics
Physics is a broad and complex field. It covers everything from sound and light to nuclear
science and geology. Because of this, it's been divided into different branches so that scientists
can specialize in their knowledge of physics.
Mechanics is one major branch of physics, and this focuses on the behavior of objects and the
forces that act upon them. Classical mechanics and quantum mechanics are two sub-fields of
this branch.
Another is thermodynamics, which is just what it sounds like: the study of heat, temperature,
and energy. Though this is but a branch of physics, it is a broad and complex field all in itself,
studied by many different types of scientists and engineers.
Because physics includes the study of light and sound, you can bet there are branches dealing
with each of these. Acoustics is the study of sound and waves, and optics is the study of light
and its properties. Both of these fields help describe how we interact with the world around us
through two of our most important senses
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through two of our most important senses.
Electromagnetism is the study of electrical and magnetic forces, both of which are major
components of physics. Without this field of study we wouldn't have electricity to power our
homes, so I'm a big fan of this one!
Fluid dynamics is a unique field of physics in that it is the study of fluids and their physical
properties. Fluids can be liquids or gases, and this is an exciting field if you like studying things
that flow.
Ever heard of a guy named Albert Einstein? He's pretty famous in the world of physics, partly
because of his theory of relativity, from which a branch of physics was developed. Simply called
relativity, this branch specifically looks at systems with properties of the theory of relativity.
Of course, this is just a short list, and there are many interdisciplinary branches of physics as
well. Fields like biophysics, physical chemistry, geophysics, and astrophysics exist as well, and
these help bridge gaps between other natural sciences and the fundamentals of physics.
Lesson Summary
Without physics you would have a difficult time living, breathing, or doing just about anything.
Physics is the study of matter and energy, but that simple description doesn't really do it justice.
Physics encompasses a wealth of topics - fluids, heat, light, sound, forces, electricity, and
magnetism, just to name a few.
Physics is considered the most fundamental science because it provides a basis for all other
sciences. Just try to do biology or chemistry without physics and you'll find you come up short.
Physics has a long and rich history. Humans have been trying to explain natural phenomena for
as long as they have been on Earth, but modern physics is considered to have come about
through the Scientific Revolution of the 16th and 17th centuries. Thanks to the hard work of
scientific pioneers like Galileo, Newton, Copernicus and others, we now have a vast and
scientifically supported body of knowledge about our natural world.
Learning Outcomes
After you've reviewed this video lesson, you should be able to:
Define physics
Summarize the early beginnings of physics and the foundation of modern physics
Identify important physicists and their contributions
Describe a number of different branches of physics
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Frequently Asked Questions
What are the 7 branches of physics?
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The seven branches of physics are optics, electromagnetism, relativity, thermodynamics,
acoustics, quantum physics, and mechanics. There are smaller categories within these
broad areas.
What is physics in simple terms?
Physics is the study of the natural world, both seen and unseen. It is a broad subject that
can be broken down into specific areas of study, like electromagnetism and optics.
What is physics and why is it important?
Physics is an important area of study because it allows scientists to understand the world,
the environment, and the interactions between objects in a system. Understanding our
world allows for appreciation, conservation, innovation of the world around us.
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