Physics

Three foundational laws formulated by Isaac Newton that describe the relationship between a body and the forces acting upon it. The first law (inertia) states an object remains at rest or in uniform motion unless acted upon by a net force; the second law relates force to mass times acceleration ($F = ma$); and the third law states every action has an equal and opposite reaction.

A fundamental principle stating that the total energy of an isolated system remains constant over time. Energy can be transformed from one form to another -- such as kinetic to potential or thermal -- but it cannot be created or destroyed. This law applies universally across all branches of physics.

Self-propagating oscillations of electric and magnetic fields that travel through a vacuum at the speed of light, approximately $3 \times 10^8$ meters per second. They span a broad spectrum from low-frequency radio waves to high-frequency gamma rays, and they require no medium for propagation, unlike mechanical waves.

A set of four fundamental laws governing heat, work, temperature, and entropy. The zeroth law establishes thermal equilibrium; the first law is conservation of energy applied to thermal systems; the second law states that entropy in an isolated system never decreases; and the third law states that absolute zero temperature cannot be reached in a finite number of steps.

The quantum mechanical principle that every particle or quantum entity exhibits both wave-like and particle-like properties depending on the experimental context. Photons, for instance, produce interference patterns like waves but also deliver energy in discrete packets when detected. This duality is central to quantum theory and challenges classical intuition.

Einstein's 1905 theory postulating that the laws of physics are the same in all inertial reference frames and that the speed of light in a vacuum is constant for all observers regardless of their motion. It leads to time dilation, length contraction, and the famous mass-energy equivalence $E = mc^2$.

An electric field is a region of space around a charged particle where other charges experience a force. Coulomb's law quantifies the electrostatic force between two point charges as proportional to the product of their charges and inversely proportional to the square of the distance between them. This inverse-square relationship mirrors the form of Newton's law of gravitation.

A fundamental limit in quantum mechanics stating that certain pairs of physical properties, such as position and momentum, cannot both be simultaneously measured with arbitrary precision. The more precisely one property is known, the less precisely the other can be determined. This is not a limitation of instruments but a fundamental feature of nature.

In Newtonian physics, gravity is a force proportional to the product of two masses divided by the square of their separation. In Einstein's general relativity, gravity is reinterpreted as the curvature of spacetime caused by mass and energy, with objects following geodesic paths through curved spacetime rather than being pulled by a force.

Fission is the splitting of a heavy atomic nucleus into lighter nuclei, releasing energy due to the conversion of nuclear binding energy, and is the process used in nuclear power plants. Fusion is the combining of light nuclei into heavier ones, which powers stars like our Sun. Both processes convert a small amount of mass into a large amount of energy according to $E = mc^2$.