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What is physics?
Beginner
The science of matter, energy, space and time and how they interact.
Physics looks for the few simple rules behind a huge range of phenomena, from a falling apple to a galaxy. It works by a loop: observe, propose a model, make a numerical prediction, test it by experiment, and revise. A theory is only useful if it can be proved wrong by a measurement, which is why physics leans so heavily on numbers and units.
Newton's gravity predicted the return of Halley's comet decades in advance. The prediction was specific enough to fail, and it did not.
Physics is not just memorising formulas. Each formula is a compact summary of a model with limits, so always ask where it stops being valid.
In more detail
Physics asks what the universe does and why, and answers with measurements, models and tests. Its power comes from expressing ideas as quantities that can be checked against experiment.
Real-world uses
- Engineers use physical models to predict bridge loads before building.
- Doctors use physical principles to interpret ultrasound and X-ray images.
- A climate scientist, a bridge engineer and a games developer all use the same physical laws, which is why one framework covers all three.
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Frequently asked questions
Is physics only for scientists?
No. The same reasoning helps with cooking times, cycling speeds, phone batteries and many other everyday questions.
How is physics different from chemistry?
Physics studies matter and energy in general, while chemistry focuses on how atoms bond and react to form substances.
What is the first thing I should do when starting a physics problem?
Write down what is known, what is asked, and the units of each quantity. Most early mistakes come from skipping this step.