What Is Physics? An International Student Guide to Physics Courses in the US

What is physics? Physics is a very broad field of study that explores the fundamental laws and mechanics of the universe. A physics degree equips you with the technical skills and knowledge you need to pursue careers in fields like engineering, software design, aerospace, teaching, and medicine. There is also the option to continue to advanced studies in physics and astronomy.

If you have an interest in studying how our universe works, then a physics degree might be the perfect choice for you. Read on to learn more about physics courses and their key concepts, and how physics applies to both academic and real-world careers. 

What Is Physics and Why Should You Study It?

Physics is the study of the fundamental laws that explain how the universe works, focusing on the properties of matter, and the forces that act upon them. Physics looks at every aspect of the physical world, from subatomic particles to the vastness of the universe, and aims to understand how everything works at its most basic level. 

Physics serves as the foundational core of all other branches of physical science, like astronomy, biology, chemistry, and even applied sciences like engineering and medicine. It plays a critical role in helping us understand the natural world, as well as our modern technological society. 

Let’s explore several core concepts and fundamental principles that form the foundation of physics as a field of study.

What Is Physics? The Basic Ideas 

Physics courses cover a range of fundamental concepts, basic principles, and theories to explore the nature of the universe and the laws that govern it. Here are several basic definitions and concepts that are the foundation of studying for a physics degree.

Matter

In physics, matter is defined as anything that has mass and occupies space with its volume. It is the substance that all physical objects are composed of, from the smallest subatomic particles to entire galaxies, and can exist in various states, like solid, liquid, gas, and plasma. Many concepts fundamental to the study of physics involve theories and laws that explain matter and its motion, such as thermodynamics and quantum mechanics.

Energy

Energy is a bit more complex, but in physics, it is defined as the ability to do work. It can exist in various forms such as kinetic energy, potential energy, thermal energy, and electromagnetic energy. Energy can’t be created or destroyed, but it can be transferred between objects or converted from one form of energy to another. Energy is a fundamental concept that drives physical processes, from powering machines to sustaining life, and plays a central role in the behavior of matter and forces in the universe.

Force

In physics, force is an interaction on an object that causes it to change its motion, direction, or shape, unless other forces act to counterbalance it. There are many known forces, and classical physics categorizes most as either contact forces or forces that act at a distance. In modern physics, however, they are broken down into four fundamental interactions: gravitational, electromagnetic, strong, and weak.

Using these fundamental concepts and through repeated experimentation and observation, physicists have determined key principles and laws to better understand our physical world. 

Several laws of physics include: 

• Newton’s Laws of Motion — describes the relationship between physical objects and the forces that act upon them, forming the foundation of modern physics. 

• The Law of Conservation of Energy — states that energy cannot be created or destroyed, only transformed from one form to another, which allows us to predict energy behavior.

• The Law of Conservation of Momentum — explains how, in an isolated system, the total momentum remains constant unless acted upon by external forces.

After understanding the core concepts of physics, it becomes clear that mathematics is vitally important in expressing these principles and solving the complex problems they present. 

Mathematics

Mathematics serves as both a precise language and an essential tool needed to describe, model, and predict physical phenomena. Through mathematical equations and formulas, physicists can quantify relationships between variables, such as force, motion, energy, and time. Mathematics allows for the formulation of fundamental laws, like Newton’s laws of motion, and helps analyze experimental data, create simulations, and solve complex problems in various areas of physics. 

As you can see, physics is a broad and diverse field with a range of areas of study, each focusing on different aspects of the natural world. With such a wide scope, let’s take a look at select areas you can study during the course of your physics degree.

What Are the Branches of Physics?

The study of physics can be categorized into classical and modern physics, with each category (or branch) defined by the time periods they were developed in, as well as the scale of their applicability. 

Classical physics is historically considered to be what was studied pre-1900 and deals with the larger observable world, operating under everyday conditions. It includes classical physics theories like Newtonian mechanics, electromagnetism, and thermodynamics which describe how motion, forces, energy, and heat function in systems that are not extremely small, extremely fast, or extremely large. Classical physics is effective in explaining the physical behaviors you encounter in daily life, such as the motion of objects, planetary orbits, and the behavior of gases.

Modern physics, on the other hand, is generally what was developed post-1900, and deals with natural behavior that classical physics cannot adequately explain. Several of the most revolutionary theories of physics were developed roughly around 1900, causing a major shift in how physics was studied from then on. Most notably, this was due to the advent of quantum mechanics and relativity. 

Quantum mechanics deals with the lowest extreme scale, describing the behavior of particles at atomic and subatomic levels. Relativity deals with the high-end of extreme conditions, with Einstein’s theory of special relativity explaining how time and space are linked for objects moving at very high speeds, while general relativity focuses on gravity and the curve of space-time.

Beyond this general categorization, the field of physics has a wide range of specialized branches, including astronomy, mechanics, nuclear physics, thermodynamics, and quantum physics.

Astronomy

As one of the oldest studied natural sciences, astronomy is a branch of physics that deals with the study of objects out in space (more commonly known as celestial bodies) and events that occur in the universe outside of the earth. This includes observable events like asteroids, comets, and supernovas, as well as theoretical concepts such as black holes and dark matter. Astronomy also has many subfields including astrophysics, astrodynamics, physical cosmology, and planetary science.

Mechanics

Considered to be the core of physics, mechanics is the branch of physics that is about the motion of objects and the forces that act upon them. Mechanics is essential for understanding how objects move, interact, and respond to external forces, relative to their environment. Mechanics is made up of subfields that include classical mechanics, aerodynamics, fluid mechanics, and statics.

Nuclear Physics

Nuclear physics studies the structure, properties, and behavior of atomic nuclei, the core of atoms, as well as other forms of nuclear matter. Nuclear physics covers processes like nuclear fusion and fission, radioactivity, and the energy that stars produce. It also has practical applications in fields like energy production, medicine, geology, archeology, and weapons development. 

With a broad understanding of the key branches in physics, it will be easier for you to understand the real-world applications of physics. 

What Are the Real-World Applications of Physics? 

As the fundamental science among the natural sciences, physics is present in all aspects of our lives, and its practical applications are responsible for many of our most important technologies and innovations. From the design of transportation systems and the construction of buildings to advancements in health care, energy production, and communication, physics plays an important role in solving real-world problems in a wide range of industries.

Just as physics studies the fundamental laws of our universe, engineering is the practical application of these laws to design and build functional devices and systems. The use of physics in engineering forms the basis for many of today’s groundbreaking technologies.

In civil engineering, principles like statics and dynamics are used to design and construct buildings, bridges, and infrastructure, ensuring safety and stability under different forces. Electrical engineers work with electromagnetism and circuit theory to design everything from power grids to consumer electronics. Aerospace engineers use physics to design and test aircraft, spacecraft, and propulsion systems, while material science engineers explore the properties of materials to create better, more durable components.

Physics also plays an important role in medical science and health care, allowing for the development of advanced diagnostic and treatment technologies. Imaging techniques like X-rays, CT scans, MRI, and ultrasound rely on physics principles such as electromagnetism, sound waves, and nuclear magnetic resonance to provide detailed views of the body’s internal structures, helping doctors diagnose diseases and injuries. Radiation therapy, which uses ionizing radiation to target and destroy cancer cells, is based on the principles of nuclear physics. Laser technologies, derived from optics, are used in precision surgeries like eye correction procedures and in tools for cutting and cauterizing tissue.

Environmental physics explores how environmental factors influence biological, physical, agricultural, and natural processes. It plays a critical role in addressing issues like climate change, air and water quality, and renewable energy resources. Environmental physics research helps optimize energy efficiency, promotes the use of renewable energy sources like solar and wind, and informs policy decisions that aim to reduce human impacts on the planet, which could lead to long-term sustainability and environmental conservation.

Which Career Opportunities Require a Physics Degree?

When you earn a physics degree, you’ll qualify for a diverse range of rewarding career opportunities. While many graduates pursue roles in physics-related industries such as research, engineering, and education, their knowledge and expertise are also highly valued in IT, scientific and technical writing, government, law, and medicine. 

A physics degree fosters critical thinking, problem-solving, technical, teamwork, and communication skills, making graduates highly adaptable and attractive to a wide range of employers across multiple industries. 

According to the U.S. Bureau of Labor Statistics, employment opportunities for physicists and astronomers are set to grow faster than average, at around 7%, from 2023 to 2033. Let’s look at several careers you can pursue with a physics degree, as well as their average annual salaries in the US, Brazil, China, and India.

Source: Salary Expert, Payscale, Glassdoor, March 2025

As you can see, a physics degree opens the door to a diverse range of rewarding career opportunities across various industries. Now, let’s explore several highly ranked physics degrees offered in the US.

Shorelight Universities with Physics Degree Programs

By studying physics in the US, international students like you can benefit from a world-class education, extensive research opportunities, and strong career prospects in a globally competitive environment. 

Several Shorelight universities have top-ranked physics courses and degree programs. Let’s learn more about these international student-friendly universities offering undergraduate degrees in physics.

Louisiana State University

Ranked #73 in the US (U.S. News & World Report), Louisiana State University’s (LSU) physics program prepares students for graduate school in physics, leading to careers in academia, government agencies like NASA, or high-tech industries. The undergraduate program offers majors in physics, astronomy, medical/health physics, and minors in physics, with opportunities to specialize in areas like secondary education or medical physics. 

Rutgers University-New Brunswick, New Jersey

Rutgers’ Department of Physics and Astronomy is ranked #28th in the nation (U.S. News & World Report), and offers a broad range of research and academic opportunities with the aim of advancing knowledge of the physical world through observation, measurement, simulation, and theory. The department caters to non-science majors, engineering and medical students, and those pursuing careers in research, providing a solid foundation in physical science through both classroom learning and hands-on research experiences.

Stony Brook University, New York

Ranked #21 by U.S. News & World Report, Stony Brook University’s physics degree gives international students the opportunity for experiential learning through applied work in geology, medicine, biochemistry, and engineering, among many other fields. Undergraduate physics and astronomy students at Stony Brook also have numerous research opportunities, financial support options, and chances to present or publish their work.

University of Illinois Chicago

Tied with LSU at #73 in the nation, the University of Illinois Chicago’s Department of Physics offers physics courses that combine top-tier research opportunities with a strong focus on undergraduate education. The department offers a BA and BS in physics and a master’s of education track in partnership with the College of Education, as well as a flexible minor in physics, allowing students to explore physics alongside other disciplines.

University of Utah

The University of Utah’s flexible physics major includes five core courses and three electives, allowing students to freely explore any of the specialized courses on offer like astrophysics, biophysics, and physics education research. Students also have the opportunity to work with industry leaders on faculty, conducting cutting-edge research on a broad range of topics in physics, astrophysics, and astronomy.

Recent Developments in the Field of Physics

Physics is not a solved science and is constantly evolving, with global researchers regularly expanding the boundaries of what we know. There is still so much to learn about the universe we live in, with each new discovery challenging what we thought we knew. In recent years, the field of physics is moving toward exciting new directions, with advancements in areas like quantum computing, dark matter, and fusion energy research.

Quantum computing is a rapidly growing, emergent field of cutting-edge computer science that takes advantage of quantum mechanical effects, such as superposition and quantum interference, to function faster and more efficiently than a classical computer could. Though it is still in its early stages, quantum computing has the theoretical potential for solving problems that require factoring large numbers, simulating molecular structures, and optimizing complex systems – and may do so far better than even modern supercomputers. 

Quantum computing discoveries could greatly benefit most industries, especially pharmaceuticals, health care, manufacturing, cybersecurity, and finance. Major tech companies like IBM, Google, and Microsoft are racing to build more powerful quantum computers to be the first in the market with viable quantum computing solutions for large-scale, industry-wide applications.

In other areas, sustainability remains a priority, with new technologies for renewable energy in development. Slow but steady progress is being made, and most nations are making an effort to transition to renewable energy, with countries like China leading the charge.

In astrophysics and cosmology, physicists are tackling mysteries like dark matter, dark energy, and the nature of black holes, which challenge our understanding of the universe. Researchers have made progress toward answering some of the major unsolved problems in physics, such as resolving ongoing inconsistencies involving current standard models and addressing long-unproven hypotheses. 

Though significant challenges remain, physics as a fundamental science will continue to drive technological and scientific progress for the foreseeable future. If you enjoy problem-solving, curiosity-driven exploration, and logical reasoning, physics could be an ideal field of study for you. 

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