In mathematics and theoretical physics, mirror symmetry is a
relationship between geometric objects called Calabi–Yau manifolds
(pictured). The term refers to a situation where two Calabi–Yau
manifolds look very different geometrically but are nevertheless
equivalent when employed as extra dimensions of string theory. Mirror
symmetry was originally discovered by physicists. Mathematicians became
interested in this relationship around 1990 when Philip Candelas, Xenia
de la Ossa, Paul Green, and Linda Parks showed that it could be used as
a tool in a branch of mathematics called enumerative geometry. Today
mirror symmetry is a major research topic in pure mathematics, and
mathematicians are working to develop a mathematical understanding of
the relationship based on physicists' intuition. Mirror symmetry is also
a fundamental tool for doing calculations in string theory, and it has
been used to understand aspects of quantum field theory, the formalism
that physicists use to describe elementary particles. Major approaches
to mirror symmetry include the homological mirror symmetry program of
Maxim Kontsevich and the SYZ conjecture of Andrew Strominger, Shing-Tung
Yau, and Eric Zaslow.
Read more: <https://en.wikipedia.org/wiki/Mirror_symmetry_(string_theory)>
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Today's selected anniversaries:
1671:
Irish-born Colonel Thomas Blood was caught trying to steal the
English Crown Jewels from the Tower of London.
<https://en.wikipedia.org/wiki/Thomas_Blood>
1877:
An 8.5 Ms earthquake struck the northern portion of Chile,
resulting in the death of 2,541 people, including victims of the ensuing
tsunami as far away as Hawaii and Japan
<https://en.wikipedia.org/wiki/1877_Iquique_earthquake>
1949:
Rainier III became Prince of Monaco, beginning a 56-year reign,
which would make him one of the longest ruling monarchs of the 20th
century.
<https://en.wikipedia.org/wiki/Rainier_III,_Prince_of_Monaco>
1964:
Ngô Đình Cẩn, de facto ruler of central Vietnam under his
brother President Ngô Đình Diệm before the family's toppling, was
executed.
<https://en.wikipedia.org/wiki/Ng%C3%B4_%C4%90%C3%ACnh_C%E1%BA%A9n>
2004:
Akhmad Kadyrov, the first President of the Chechen Republic,
and about 30 others were killed by a bomb during a World War II
memorial victory parade in Grozny.
<https://en.wikipedia.org/wiki/Akhmad_Kadyrov>
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Wiktionary's word of the day:
green gown:
(now archaic, historical) A dress that has been stained green from
rolling in the grass; generally with allusion to sexual activity,
especially a woman's loss of virginity.
<https://en.wiktionary.org/wiki/green_gown>
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Wikiquote quote of the day:
 Man is a substantial emigrant on a pilgrimage of being, and
it is accordingly meaningless to set limits to what he is capable of
being.
--José Ortega y Gasset
<https://en.wikiquote.org/wiki/Jos%C3%A9_Ortega_y_Gasset>