Double Slit Experiment: The Test That Revealed Two Realities
The double slit experiment shows that light and matter behave as both waves and particles. First performed by Thomas Young in 1801, it remains quantum mechanics' most revealing test.
Physics and Mathematics
54 glossary terms
Physics and mathematics are the languages scientists use to describe the structure of reality. The terms here range from the familiar (prime numbers, Planck length) to concepts that still unsettle physicists a century after they were proposed, such as wave-particle duality and quantum entanglement. Mathematics runs alongside, not because physics cannot stand without it, but because so many physical ideas become precise only when expressed in the shorthand of equations. This glossary covers the quiet workhorses of classical physics, the strangeness of quantum mechanics, and the mathematical structures that let theorists probe phenomena no instrument can yet reach.
Fermions: The Particles That Build All Matter
Fermions are half-integer spin particles that obey the Pauli exclusion principle, building all ordinary matter.
Fibonacci Numbers: Nature's Hidden Sequence
Fibonacci numbers are integers where each equals the sum of the two before it. The pattern links pure mathematics to nature.
Composite Numbers: The Building Blocks of Arithmetic
A composite number is a positive integer greater than 1 that can be divided evenly by at least one number other than 1 and itself.
Bosons: The Particles That Carry Nature's Forces
Bosons are integer-spin subatomic particles that carry nature's forces and can occupy the same quantum state simultaneously.
Bose-Einstein Condensate: The Fifth State of Matter Explained
A Bose-Einstein condensate forms when bosons cool to near absolute zero and merge into one quantum state, creating a fifth state of matter with properties visible only at quantum scales.
Brownian Motion: The Random Dance That Proved Atoms Exist
Brownian motion is the irregular, jittering movement of small particles suspended in a liquid or gas, caused by constant collisions with the surrounding fluid molecules.
Anyons: The Particles That Break the Fermion-Boson Rule
Anyons are quasiparticles that exist only in two-dimensional systems and follow statistical rules different from those of fermions and bosons, with applications in topological quantum computing.
Andromeda Paradox: When "Now" Depends on Who Is Walking
The Andromeda Paradox is a thought experiment showing that two observers moving at different velocities disagree about what is happening "now" at distant locations, with walking-speed differences producing a days-long shift at the Andromeda Galaxy.
Absolute Zero: The Temperature Nothing Can Reach
Absolute zero is the lowest temperature matter can reach, 0 kelvin or -273.15 degrees Celsius, where atoms occupy their lowest energy state but quantum mechanics prevents them from stopping entirely.