An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

The quality of a system that can be expanded or reduced in scale. Scalability allows computer equipment and software programs to be upgraded easily, rather than needing to be replaced.

→ scale; → -able.

Any quantity which is sufficiently defined only with its magnitude, when given in appropriate units. Compare → vector.
See also:
→ electric scalar potential, → scalar field, → scalar potential, → scalar processor, → scalar product, → scalar wave, → scalar-tensor theory, → tensor-vector-scalar (TeVeS) theory.

Of or pertaining to → scale.

A → tensor density of → order 0.

→ scalar; → density.

A → field whose value at every point of space is independent of → direction and → position. Examples include → temperature distribution throughout space and → pressure distribution in a → fluid. Similarly, a → potential field, such as the Newtonian → gravitational field or the electric potential in → electrostatics are scalar fields. In quantum field theory, a scalar field is associated with → spin zero particles, such as → mesons or → bosons. Therefore, the → Higgs boson is associated with a scalar field. The → derivative of a scalar field results in a → vector field is called the → gradient. In contrast to a vector field, a scalar field is → invariant under the → rotation of the → coordinate system. The → inflation in the → early Universe is supposed to be driven by a scalar field, called the → inflaton field.

→ scalar; → field.

The energy density fluctuations in the → photon-baryon plasma that bring about hotter and colder regions. This perturbation creates velocity distributions that are out of phase with the acoustic density mode. The fluid velocity from hot to cold regions causes blueshift of the photons, resulting in → quadrupole anisotropy.

→ scalar; → perturbation.

Computers: A type of central processing unit in which only one operation on data is executed at a time. By contrast, in a vector processor, a single instruction operates simultaneously on multiple data items.

→ scalar; → processor.

A multiplication of two vectors giving a scalar. The scaler product of V₁ and V₂ is defined by: V₁.V₂ = V₁.V₂ cos α, where V₁ and V₂ are the magnitudes of the vectors and α is the angle between them. Same as dot product. See also → vector product.

→ scalar; → product.

In theories of gravitation, a kind of → gravitational wave, transversal and/or longitudinal, characterized by → spin zero.

→ scalar; → wave.

An alternative to the standard → general relativity of gravity that contains not only the → tensor field (or → metric), but also a → scalar field. In this formalism, the → gravitational constant is considered to vary over time. As a consequence, the measured strength of the gravitational interaction is a function of time. Same as → Jordan-Brans-Dicke theory.

→ scalar; → tensor; → theory.

1a) A succession or progression of steps or degrees.
1b) A standard of measurement or estimation; point of reference by which to gauge or rate.
2) To reduce or increase according to a common proportion (often followed by down or up).

M.E., from L. scalae "ladder, stairs."

Marpel, literally "measuring stick, measuring step," on the model of Ger. Maßstab from Mass "measure" + Stab "stick, bar, pole, baton." The first element from Mod./Mid.Pers. mar "measure, count," from Av. mar- "to count, remember;" Skt. smr, smarati "to remember, he remembers;" L. memor, memoria; Gk. mermera "care," martyr "witness." The second element pel "stick, a bit of wood;" pel can also be interpreted as the contraction of pellé "staircase, ladder."

In computer science, to reduce the processing power of the same node/system by reducing its resources (CPU, RAM, etc.). This type of → vertical scaling is opposite to → scale up. See also → scale in, → scale out.

→ scale; → down.

Math.: A number which scales, or multiplies, some quantity. In the equation y = Cx, C is the scale factor for x. C is also the coefficient of x, and may be called the constant of proportionality of y to x.
Geometry: The ratio of any two corresponding lengths in two similar geometric figures. The ratio of areas of two similar figures is the square of the scale factor.

→ scale; → factor.

The height within which some parameter, such as pressure or density, decreases by a factor of e. For example, an atmospheric scale height of 100 km means that the value at 100 km is 1/e the value at the surface.

→ scale; → height.

In computer science, to reduce the number of nodes (servers), as opposed to → scale out. Scale-in is a type of → horizontal scaling. See also → scale up, → scale down.

→ scale; → in.

In computer science, to upgrade a system by increasing the number of nodes. For example, instead of going from a CPU of X and memory of Y to a CPU with 4X and 4Y memory, use 4 machines with CPU of X and memory of Y. This is a type of → horizontal scaling. See also → scale in, → scale up, → scale down.

→ scale; → out.

In computer science, to increase the processing power of the same node/system by increasing its resources (CPU, RAM, etc.). This is a type of → vertical scaling opposite to → scale down. For example, instead of a machine with a CPU running at speed of X and having Y gigabytes of memory, use a machine with a CPU running at speed of 4X and a memory of 4Y gigabytes. See also → scale in, → scale out.

→ scale; → up.

A triangle no two sides of which are equal.

From L.L. scalenus, from Gk. skalenos "uneven, unequal, rough," from skallein "chop, hoe," related to skolios "crooked," from PIE base *(s)qel- "crooked, curved, bent;" → triangle.

Sebar, → triangle; nâjur-pahlu "dissimilar sides," from nâjur "dissimilar, ill-matched" + pahlu "side, flank" (Mid.Pers. pahlug "side, rib," Av. pərəsu- "rib," Ossetic fars "side, flank," cf. Skt. párśu- "rib," Lith. piršys (pl.) "horse breast").

An electronic circuit devised to give a single pulse after a prescribed number of input pulses have been received.

Agent noun from → scale.

1) Altering original variable values (according to a specific function or an algorithm) into a range that meet particular criteria.
2) The ability of a system, or process, to handle a growing load in regards to capacity. It has two types: → vertical scaling and → horizontal scaling.

→ scale; → -ing.

The part of the head where the hair grows from.

M.E., perhaps from O.Norse skālpr "sheath," related to O.Norse skalli "a bald head," from PIE root *(s)ker- "to cut," → bark.

Keler, from Zâhedân Baloci keler "scalp," cognate with kâlun, → bark.