Physicists and astronomers typically do the following:

• Develop scientific theories and models to explain the properties of the natural world, such as the force of gravity or the formation of subatomic particles
• Plan and conduct scientific experiments and studies to test theories and discover properties of matter and energy
• Write proposals and apply for research funding
• Do mathematical calculations to analyze physical and astronomical data, such as for new material properties or the existence of planets in distant solar systems
• Design new scientific equipment, such as telescopes and lasers
• Develop computer software to analyze and model data
• Write scientific papers for publication
• Present research findings at conferences and lectures

Physicists explore the fundamental properties and laws that govern space, time, energy, and matter. They may study theory, design and perform experiments, or apply their knowledge in developing materials or equipment.

Astronomers study planets, stars, and other celestial bodies. They use ground-based equipment, such as optical telescopes, and space-based equipment, such as the Hubble Space Telescope. Some astronomers study distant galaxies and phenomena such as black holes and neutron stars. Others monitor space debris that could interfere with satellite operations.

Many physicists and astronomers work in applied research. They use their knowledge to develop technology or solve problems in areas such as energy storage, electronics, communications, and navigation. Others work in basic research to develop theories that explain concepts such as what gravity is or how the universe was formed.

Astronomers and physicists typically work on research teams with engineers, technicians, and other scientists. Senior astronomers and physicists may assign tasks to other team members and monitor their progress. They also may need to find and apply for research funding.

Experimental physicists develop equipment or sensors to study properties of matter, create theories, and test theories through experiments. Theoretical and computational physicists develop concepts that predict properties of materials or describe unexplained results. Although all of physics involves the same fundamental principles, physicists generally specialize in one of many subfields. The following are examples of physicist job titles:

Atomic, molecular, and optical physicists study atoms, simple molecules, electrons, and light and the interactions among them. Some look for ways to control the states of individual atoms, because such control might allow for further miniaturization or might contribute toward developing new materials or technology.

Computational physicists study the use of algorithms, numerical analysis, and datasets to explore the interaction between theoretical and experimental physics. They explore complex phenomena in atoms, molecules, plasmas, and high-energy particles; problems in astrophysics; and applied phenomena, such as traffic, the behavior of oceans, and biological dynamics.

Condensed matter and materials physicists study the physical properties of matter in molecules, nanostructures, or novel compounds. They study a wide range of phenomena, such as superconductivity, liquid crystals, sensors, and nanomachines.

Health physicists study the effects of radiation on people, communities, and the environment. They manage the beneficial use of radiation while protecting workers and the public from potential hazards posed by radiation.

Medical physicists work in healthcare and use their knowledge of physics to develop new medical technologies and radiation-based treatments. For example, some develop safer radiation therapies for cancer patients. Others develop improved imaging technologies for radiant energy, such as magnetic resonance imaging (MRI) and ultrasound imaging.

Particle and nuclear physicists study the properties of atomic and subatomic particles, such as quarks, electrons, and nuclei and the forces that cause their interactions.

Plasma physicists study plasmas, a distinct state of matter that occur naturally in stars and interplanetary space and artificially in products such as neon signs and fluorescent lights. These physicists may study ways to create fusion reactors as a potential energy source.

Quantum information physicists study ways to use quantum objects, such as atoms and photons, to probe information processing, computing, and cryptography. They focus on ways to use the fundamental nature of quantum mechanics and its associated uncertainties.

Unlike physicists, astronomers cannot experiment on their subjects, which are so far away that they cannot be touched or interacted with. Therefore, astronomers generally make observations or work on theory. Observational astronomers view celestial objects and collect data on them. Theoretical astronomers analyze, model, and speculate about systems and how they work and evolve. The following are examples of astronomer job titles:

Cosmologists and extragalactic/galactic, planetary, and stellar astronomers study the creation, evolution, and possible futures of the universe and its galaxies, stars, planets, and solar systems. These astronomers develop and test concepts, such as string theory and dark-matter and dark-energy theories, and study models of galactic and stellar evolution, planetary formation, and interactions between stars.

Optical and radio astronomers use optical, radio, and gravitational-wave telescopes to study the motions and evolution of stars, galaxies, and the larger scale structure of the universe.

Physicists also may work in interdisciplinary fields, such as biophysics, chemical physics, and geophysics. For more information, see the profiles on biochemists and biophysicists and geoscientists.

People who have a background in physics or astronomy also may become professors or teachers. For more information, see the profiles on high school teachers and postsecondary teachers.