Gamma

Gamma (uppercase Γ, lowercase γ; Greek: Γάμμα) is the third letter of the Greek alphabet. In the system of Greek numerals it has a value of 3. It was derived from the Phoenician letter Gimel . Letters that arose from Gamma include the Roman C and G and the Cyrillic letters Ge Г and Ghe Ґ.

In Modern Greek, it represents either a voiced velar fricative /ɣ/ or a voiced palatal fricative /ʝ/. In Ancient Greek, it represented a voiced velar stop /ɡ/. Before velars, it represents a velar nasal /ŋ/ in Modern as well as Ancient Greek, and a double gamma represents the sequence /ŋɡ/ (phonetically varying [ŋɡ~ɡ]) or /ŋɣ/.

Combinations with other Greek letters

The gamma can be combined with other letters or itself.

• A gamma combined with another gamma (γγ) is pronounced like the ng in "finger"
• A gamma combined with xi (γξ) is pronounced roughly like the nx in "sphinx"
• A gamma combined with chi (γχ) is pronounced like the nkh in "ankh"
• A gamma combined with kappa (γκ) is pronounced like the nk in "banker"
• A kappa combined with gamma (κγ) has no English equivalent, it is a geminated g, like the one in "gate", but longer.

Use as a symbol or a term

The lower-case letter $\gamma$ is used as a symbol for:

• gamma radiation in nuclear physics
• surface energy in materials science
• the Lorentz factor in theory of relativity
• The heat capacity ratio Cp/Cv in thermodynamics
• gamma oscillation in neuroscience
• Gamma Motor Neurons in neuroscience
• antibiotic concentration (1 $\gamma$ = 1 µg/ml) in microbiology
• the power by which the luminance of an image is increased in gamma correction
• The Euler–Mascheroni constant
• Phonetics uses gamma as the symbol for the voiced velar fricative
• In mechanical engineering,
  • specific weight
  • The shear rate of a fluid is represented by a lower case gamma with a dot above it: ${\dot {\gamma }}$

The upper-case letter $\Gamma$ is used as a symbol for:

• In mathematics, the gamma function (usually written as $\Gamma$-function) is an extension of the factorial to complex numbers
• circulation in fluid mechanics
• As reflection coefficient in physics and electrical engineering
• In physics, the quantity Torque

See also

• Г, г - Ge (Cyrillic)
• G, g - Latin
• photon