Lene Hau. Lene Vestergaard Hau (born November 13, 1959 in Vejle, Denmark) is a Danish physicist. In 1999, she led a Harvard University team who, by use of a Bose-Einstein condensate, succeeded in slowing a beam of light to about 17 metres per second, and, in 2001, was able to stop a beam completely.
Zeta is the sixth letter of the Greek alphabet. In the system of Greek numerals, it has a value of 7. It was derived from the Phoenician letter zayin. Letters that arose from zeta include the Roman Z and Cyrillic Ð.
Theta is most often used to represent unknown angles, especially in the study of trigonometry. Theta represents an angle in degrees, but not in radians. Theta (Î¸) is a Greek letter, typically denoting an unknown angle. Depending on the context of the problem, it could be in degrees or radians.