Scientific Glossary
- Ab initio: from first principles
- Acceleration of gravity: Acceleration of a freely falling body due to a large gravitational field, equal to approximately 9.8 meters per second per second near Earth.
- Accretion disk: A flat pancakelike structure of interstellar material surrounding a central star or black hole that is being pulled gravitationally onto the large object at its center.
- Adenosine Triphosphate: A biomolecule that provides energy for muscle contraction and other cellular functions.
- Adiabatic electron affinity: The energy released when an electron attaches to an atom or molecule to form a negative ion.
- Anion: A negatively charged ion, which has more electrons than protons.
- Apoenzyme: The inactive protein portion of an enzyme that requires the attachment of a cofactor to form an active enzyme.
- Arbitrary electronic waveform:
- Astrosphere: Analogs of the Sun's heliosphere that are produced when the stellar wind interacts with interstellar gas flow.
- Attosecond: One quintillionth (10-18) of a second; one thousandth of a femtosecond.
- Atom interferometer: A device that exploits the interference of matter waves to probe the structure and dynamics of tiny structures.
- Atom waveguide: A pipe that can trap and transport atoms.
- Atomic-force microscope: A microscope that uses a flexible cantilever to produce a 3D image of a sample surface.
- Atomtronics: Cold atom analogs of semiconductors, diode junctions, or transistors.