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Modified Newtonian dynamics ( MOND) is a theory that proposes a modification of Newton's second law to account for observed properties of galaxies. Its primary motivation is to explain galaxy rotation curves without invoking dark matter, and is one of the most well-known theories of this class.
Rainmeter is a free and open-source desktop customization utility for Windows released under the GNU GPL v2 license. It allows users to create and display user-generated customizable desktop widgets or applets called "skins" that display information. [3] [4] Ready to use collections of skins can be downloaded and installed in packages known as ...
Doomsday Clock. The Doomsday Clock is a symbol that represents the likelihood of a human-made global catastrophe, in the opinion of the members of the Bulletin of the Atomic Scientists. [1] Maintained since 1947, the clock is a metaphor, not a prediction, for threats to humanity from unchecked scientific and technological advances.
The Chartres astronomical clock [ fr] in Chartres Cathedral is an astrolabe clock, installed in 1528. It was overhauled, its mechanism replaced by an electric mechanism, in 2009. Haguenau. The facade of the Musée alsacien displays an astronomical clock, a modern copy of the clock of the Ulm Rathaus.
History of timekeeping devices. A marine sandglass. It is related to the hourglass, nowadays often used symbolically to represent the concept of time. The history of timekeeping devices dates back to when ancient civilizations first observed astronomical bodies as they moved across the sky. Devices and methods for keeping time have gradually ...
The core of the traditional radio frequency atomic clock is a tunable microwave cavity containing a gas. In a hydrogen maser clock the gas emits microwaves (the gas mases) on a hyperfine transition, the field in the cavity oscillates, and the cavity is tuned for maximum microwave amplitude.
The Prague astronomical clock or Prague Orloj ( Czech: Pražský orloj [praʃskiː orloj]) is a medieval astronomical clock attached to the Old Town Hall in Prague, the capital of the Czech Republic . The clock was first installed in 1410, making it the third-oldest astronomical clock in the world and the oldest clock still in operation.
The modern 24-hour clock is the convention of timekeeping in which the day runs from midnight to midnight and is divided into 24 hours. This is indicated by the hours (and minutes) passed since midnight, from 00 (:00) to 23 (:59), with 24 (:00) as an option to indicate the end of the day. This system, as opposed to the 12-hour clock, is the ...