independent gravity measurement
61Euclidean geometry — A Greek mathematician performing a geometric construction with a compass, from The School of Athens by Raphael. Euclidean geometry is a mathematical system attributed to the Alexandrian Greek mathematician Euclid, which he described in his… …
62nature, philosophy of — Introduction the discipline that investigates substantive issues regarding the actual features of nature as a reality. The discussion here is divided into two parts: the philosophy of physics and the philosophy of biology. In this… …
63solids, mechanics of — ▪ physics Introduction science concerned with the stressing (stress), deformation (deformation and flow), and failure of solid materials and structures. What, then, is a solid? Any material, fluid or solid, can support normal forces.… …
64Wave–particle duality — Quantum mechanics Uncertainty principle …
65Apache Point Observatory Lunar Laser-ranging Operation — APOLLO shooting a laser at the Moon. The laser pulse is reflected from the retroreflectors on the Moon (see below) and returned to the telescope. The round trip time tells the distance to the Moon to great accuracy. In this picture the Moon is… …
66United States — a republic in the N Western Hemisphere comprising 48 conterminous states, the District of Columbia, and Alaska in North America, and Hawaii in the N Pacific. 267,954,767; conterminous United States, 3,022,387 sq. mi. (7,827,982 sq. km); with… …
67Earth — This article is about the planet. For other uses, see Earth (disambiguation). Earth   …
68Philosophy of science — is the study of assumptions, foundations, and implications of science. The field is defined by an interest in one of a set of traditional problems or an interest in central or foundational concerns in science. In addition to these central… …
69History of technology — The history of technology is the history of the invention of tools and techniques. Background knowledge has enabled people to create new things, and conversely, many scientific endeavors have become possible through technologies which assist… …
70Smart grid — Public infrastructure …
