Penrosen.
/ˈpɛnrəʊz/, U.S. /ˈpɛnˌroʊz/ Mathematics and Physics.
1. Penrose process n. a mechanism postulated by Penrose whereby energy can under certain circumstances escape from a black hole (see quot. 1986).Penrose described the process in 1969 ( Proc. Florence Inaugural Conf. European Physical Soc. 270/2 in Rivista del Nuovo Cimento 1).
ΘΚΠ
the world > the universe > star > kind of star > black hole > [noun] > mechanism whereby energy can escape
Penrose process1970
1970 Physical Rev. Lett. 25 1597/1 The Penrose process is most efficient when the reduction of mass is greatest for a given reduction in angular momentum.
1986 Astrophysical Jrnl. 307 38 The Penrose process..envisages a particle incident from infinity, entering the ergosphere, and splitting into two fragments, one of which follows a negative energy orbit while the other escapes to infinity with a total energy greater than that of the incident particle, thereby extracting energy from the hole.
2003 Physics Rep. 377 389 We illustrate how the exotic physics of black hole spin, such as the Penrose and Blandford–Znajek processes, are now open to observational study.
2. Penrose diagram n. a (usually two-dimensional) representation of space–time in which infinity is depicted as a boundary to the finite regions.Introduced by Penrose in 1964, in C. de Witt & B. de Witt Relativity, Groups & Topology 565.
ΘΚΠ
the world > relative properties > number > graph or diagram > [noun] > diagram
diagram1839
abac1890
histogram1891
alignment diagram1905
alignment chart1908
argand1908
nomogram1909
nomograph1909
histograph1915
Karnaugh map1958
Penrose diagram1973
the world > matter > physics > relativity > space-time > [noun] > representation of
Penrose diagram1973
1973 S. W. Hawking & G. F. R. Ellis Large Scale Struct. Space-Time v. 123 One can also represent the conformal structure of infinity by drawing a diagram of the (t′, r′) plane... In fact, the structure of infinity in any spherically symmetric space–time can be represented by a diagram of this sort, which we shall call a Penrose diagram.
1988 J. D. Barrow & F. J. Tipler Anthropic Cosmol. Princ. (rev. ed.) x. 632 The region conformal to the entire original cosmological model can be drawn as a two-dimensional figure called a Penrose diagram (or conformal diagram), in which the time dimension and one of the three spatial dimensions appear in the figure.
2002 Differential Geom. & its Applic. 17 180 The 0 in the Penrose diagram above represents a vanishing Ψ.
3. attributive. Designating or relating to (a) a tiling of a plane using a finite number of tile shapes according to certain constraints (such that no translation of the plane maps each tile precisely on to another), resulting in a nonperiodic pattern; (also in extended use) designating or relating to the analogous concept in three dimensions; esp. in Penrose tiling; (b) an element used in such a tiling, lattice, etc.; esp. in Penrose tile.Described by Penrose in 1974 in Bull. Inst. Math. & its Applic. 10 266–271 for four or more different shapes and subsequently for two-element tilings in 1978 ( Eureka 39 16–39). Penrose was not, however, the first to discover the existence of such tilings, first found in a form consisting of six elements.
ΘΚΠ
the world > relative properties > number > geometry > surface > [noun] > plane > tiling of
stellation1938
Penrose1975
the world > relative properties > number > geometry > shape or figure > [noun] > two-dimensional > other
amblygon1570
obliquea1608
triangulate1610
pelecoid1706
leaf1716
oblongitude1739
hexagram1863
polystigm1863
tetragram1863
tetrastigm1863
trigram1882
tetromino1954
tromino1954
tetrabolo1961
Penrose tile1975
1975 R. M. Robinson (title) Comments on Penrose tiles.
1977 Sci. Amer. Jan. 115/1 To approach the full beauty and mystery of the Penrose tiling one should make at least 100 kites and 50 darts.
1984 Physical Rev. B. 32 5765/1 The underlying 5 D space-group symmetry of the Penrose lattices has not been revealed before.
1986 Sci. Amer. Aug. 39/3 If the Penrose rhombohedrons are to be a good description of a particular shechtmanite alloy, the variations must be small.
1992 Economist 22 Aug. 76/1 Quasi-crystals..not only lack traditional symmetry, but show disturbing signs of the forbidden five and eight-fold varieties. They are composed of three-dimensional analogues to Penrose tiles.
1999 New Scientist 27 Feb. 44/3 The Penrose tiling looks cock-eyed close up, yet over large distances the tiles tend to form repeating patterns with fivefold order, just like quasicrystals.
This entry has been updated (OED Third Edition, September 2005; most recently modified version published online March 2022).
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n.1970