Einstien's theory

Einstein's Formula

Mass is a form of energy? In 1905, Albert Einstein (1873-1955) suggested that mass and energy are equivalent while developing his special theory of relativity. The famous mass-energy equivalence relation states that where E is the energy equivalent or mass energy, m is the mass of a body and is the speed of light. It is difficult to show a simple logical path through which Einstein came to his equation. It was merely an hypothesis made by him from special relativity and Maxwell's equations.

James Clerk Maxwell Portait by G. Lowes Dickinson/courtesy Caltech Archives.

Energy gain/loss in everyday examples can, however, hardly show any noticeable change in mass. This is because the total mass of an object changes only by a tiny fraction. To check Einstein's equation, we need something with tiny mass, so that an appreciable change in total mass can be measured. Radioactive decay, a nuclear reaction, is a choice. In fact, Einstein tested his own equation with a lump of radium salt to see if it lost weight as it gave off radiation. Today, the mass-energy equivalence relation has an important implication in nuclear industry. Full Resolution One of only three existing manuscripts (two of them are housed at the Albert Einstein Archives) which contain Einstein's famous formula, E=mc². Einstein's formula, which describes the relationship between energy (E), mass (m) and the speed of light (c), derives from Einstein's special theory of relativity. This theory postulates that time and space are relative - how we measure time and space depends on our state of motion relative to other observers. The formula E=mc² first appeared in an article by Einstein in 1905, using a different notation, and in 1907 he fully generalized the concept to the equivalence of mass and energy. The implication of the formula thus became that a small amount of matter could, in principle, be converted into a vast amount of energy. The realization of this principle in practice became a possibility in the 1930's with the discovery of nuclear fission, which led ultimately to the development of nuclear weapons. After the Second World War, Einstein's formula became synonymous with the nuclear age. The popular science magazine, Science Illustrated, asked Einstein to write this article. In his choice of the title, "The Most Urgent Problem of Our Time", Einstein alluded to his support for the nuclear disarmament movement.

Azimuth

Position is described in terms of an angle within the range -360deg to 360deg. The value 0deg is directly ahead of the individual, in the center of the sound stage. 90deg is directly to the individual's right, 180deg is directly behind him, and 270deg (or, equivalently and more conveniently, -90deg) directly to his left.

left-side

This value is equivalent to 270deg.

far-left

This value is equivalent to 300deg. When used with the keyword behind, this value is equivalent to 240deg.

left

This value is equivalent to 320deg. When used with the keyword behind, this value is equivalent to 220deg.

center-left

This value is equivalent to 340deg. When used with the keyword behind, this value is equivalent to 200deg.

center

This value is equivalent to 0deg. When used with the keyword behind, this value is equivalent to 180deg.

center-right

This value is equivalent to 20deg. When used with the keyword behind, this value is equivalent to 160deg.

right

This value is equivalent to 40deg. When used with the keyword behind, this value is equivalent to 140deg.

far-right

This value is equivalent to 60deg. When used with behind, this value is equivalent to 120deg.

right-side

This value is equivalent to 90deg.

leftwards

Moves the sound to the left, relative to the current angle. More precisely, subtracts 20 degrees. Arithmetic is carried out modulo 360 degrees. Note that leftwards is more accurately described as "turned counter-clockwise," since it always subtracts 20 degrees counter-clockwise, even if the inherited azimuth is already behind the listener (in which case, as a consequence of leftwards, the sound actually appears to move to the right).

rightwards

Moves the sound to the right, relative to the current angle. More precisely, adds 20 degrees. Arithmetic is carried out modulo 360 degrees. Note that rightwards is more accurately described as "turned clockwise," since it always adds 20 degrees clockwise, even if the inherited azimuth is already behind the listener (in which case, as a consequence of rightwards, the sound actually appears to move to the left).

inherit

Use the same computed value as the parent element for this property.