Philosophy and Science of Time

-
The belief in time as an absolute has a long tradition in philosophy and science. It still underlies the common sense notion of time. Isaac Newton, in formulating the basic concepts of classical physics, compared absolute time to a stream flowing at a uniform rate of its own accord. In everyday life, we likewise regard each instant of time as somehow possessing a unique existence apart from any particular observer or system of timekeeping. Inherent in the concept of absolute time is the assumption that the simultaneity of two given events is also absolute. In other words, if two events are simultaneous for one observer, they are simultaneous for all observers.

Comments

Post a Comment

Popular posts from this blog

Solar System

-
Image
Solar System, the Sun and everything that orbits the Sun, including the nine planets and their satellites ; the asteroids and comets ; and interplanetary dust and gas. The term may also refer to a group of celestial bodies orbiting another star (see Extrasolar Planets ). In this article, solar system refers to the system that includes Earth and the Sun. The dimensions of the solar system are specified in terms of the mean distance from Earth to the Sun, called the astronomical unit (AU). One AU is 150 million km (about 93 million mi). The most distant known planet, Pluto , orbits about 39 AU from the Sun. Estimates for the boundary where the Sun’s magnetic field ends and interstellar space begins—called the heliopause—range from 86 to 100 AU. The most distant known planetoid orbiting the Sun is Sedna, whose discovery was reported in March 2004. A planetoid is an object that is too small to be a planet. At the farthest point in its orbit, Sedna is about 900 AU from the Sun. Com
Read more

Mirfak

-
Mirfak, sometimes spelled Mirphak or Marfak, brightest star in the constellation Perseus, the Warrior. The star is also known as Algenib and is designated Alpha Persei. The name Mirfak is derived from the Arabic phrase Mirfaq al Thurayya, the “Elbow Nearest the Many Little Ones.” This refers to Mirfak’s position in Perseus near the Pleiades star cluster. Mirfak lies near the north celestial pole, a point in the sky about which the stars in the northern hemisphere appear to rotate. This appearance is actually due to the rotation of the earth. Observers who are north of latitude 40° north can see Mirfak all night long throughout the year, circling the north celestial pole. For this reason, Mirfak is called a north circumpolar star. Observers in the southern hemisphere can see Mirfak low in the northern sky from September through November. Stars that are visible to the unaided eye, such as Mirfak, belong to the earth’s home galaxy, the Milky Way , and tend to be very bright or relativel
Read more

space exploration

-
Space exploration, the investigation of physical conditions in space and on stars, planets, and other celestial bodies through the use of artificial satellites (spacecraft that orbit the earth), space probes (spacecraft that pass through the solar system and that may or may not orbit another celestial body), and spacecraft with human crews. Satellites and Probes Although studies from earth using optical and radio telescopes had accumulated much data on the nature of celestial bodies, it was not until after World War II that the development of powerful rockets made direct space exploration a technological possibility. The first artificial satellite, Sputnik I, was launched by the USSR (now Russia) on Oct. 4, 1957, and spurred the dormant U.S. program into action, leading to an international competition popularly known as the "space race." Explorer I, the first American satellite, was launched on Jan. 31, 1958. Although earth-orbiting satellites have by far accounted for t
Read more