as the most famous failed experiment due the ironic disproval of aetheres existence and subsequent suggestion of a constant speed of light.

While Einstein's special relativity predicted time dilation due to velocity, general relativity predicted a time dilation would also occur due to differences in gravitational field potentials. For instance, an object on the earth's surface would age slower than an object high in the

The notion of time pervades our everyday lives so strongly that we often take it for granted. Time is so familiar yet is one of the most puzzling subjects of modern science.

Historically, the first concept of time as it relates to theoretical physics was of absolute time. That is, time is assumed to be a fixed entity and all observers’ measure the same time. In 1676, by observing the motion of Jupiter's moons, Danish astronomer Ole R?mer discovered that light had a finite speed. The discoveries lead to some interesting revelations about light's relationship to time and how when we look at an object, we are seeing it as it was in the past. Though the effect is noticeable at astronomical distances, the speed of light is so great that there is little to no noticeable effect in day to day life, and thus Isaac Newton's classical physics and the notion of absolute time were accurate enough to be taken as correct. The idea of absolute time matches our everyday experiences so strongly that it prevailed for many generations until the early 20th century when Albert Einstein developed his Special and General theories of relativity.

Einstein's theory took the speed of light to be constant regardless of the motion of an observer, which meant that time was in fact, not constant. The faster something is traveling, the slower time will pass for that object compared to a stationary or slower moving object. Though Einstein simply assumed the speed of light to be constant, it was empirically suggested in 1887 by an experiment performed by Albert Michelson and Edward Morley who intended to detect the presence of luminiferous aether thought to be permeating "empty" space. The event is commonly known as the most famous failed experiment due the ironic disproval of aetheres existence and subsequent suggestion of a constant speed of light.

While Einstein's special relativity predicted time dilation due to velocity, general relativity predicted a time dilation would also occur due to differences in gravitational field potentials. For instance, an object on the earth's surface would age slower than an object high in the

tronomer Ole R?mer discovered that light had a finite speed. The discoveries lead to some interesting revelations about light's relationship to time and how when we look at an object, we are seeing it as it was in the past. Though the effect is noticeable at astronomical distances, the speed of light is so great that there is little to no noticeable effect in day to day life, and thus Isaac Newton's classical physics and the notion of absolute time were accurate enough to be taken as correct. The idea of absolute time matches our everyday experiences so strongly that it prevailed for many generations until the early 20th century when Albert Einstein developed his Special and General theories of relativity.

Einstein's theory took the speed of light to be constant regardless of the motion of an observer, which meant that time was in fact, not constant. The faster something is traveling, the slower time will pass for that object compared to a stationary or slower moving object. Though Einstein simply assumed the speed of light to be constant, it was empirically suggested in 1887 by an experiment performed by Albert Michelson and Edward Morley who intended to detect the presence of luminiferous aether thought to be permeating "empty" space. The event is commonly known as the most famous failed experiment due the ironic disproval of aetheres existence and subsequent suggestion of a constant speed of light.

While Einstein's special relativity predicted time dilation due to velocity, general relativity predicted a time dilation would also occur due to differences in gravitational field potentials. For instance, an object on the earth's surface would age slower than an object high in the

otion of absolute time were accurate enough to be taken as correct. The idea of absolute time matches our everyday experiences so strongly that it prevailed for many generations until the early 20th century when Albert Einstein developed his Special and General theories of relativity.

Einstein's theory took the speed of light to be constant regardless of the motion of an observer, which meant that time was in fact, not constant. The faster something is traveling, the slower time will pass for that object compared to a stationary or slower moving object. Though Einstein simply assumed the speed of light to be constant, it was empirically suggested in 1887 by an experiment performed by Albert Michelson and Edward Morley who intended to detect the presence of luminiferous aether thought to be permeating "empty" space. The event is commonly known as the most famous failed experiment due the ironic disproval of aetheres existence and subsequent suggestion of a constant speed of light.

While Einstein's special relativity predicted time dilation due to velocity, general relativity predicted a time dilation would also occur due to differences in gravitational field potentials. For instance, an object on the earth's surface would age slower than an object high in the

nstant. The faster something is traveling, the slower time will pass for that object compared to a stationary or slower moving object. Though Einstein simply assumed the speed of light to be constant, it was empirically suggested in 1887 by an experiment performed by Albert Michelson and Edward Morley who intended to detect the presence of luminiferous aether thought to be permeating "empty" space. The event is commonly known as the most famous failed experiment due the ironic disproval of aetheres existence and subsequent suggestion of a constant speed of light.

While Einstein's special relativity predicted time dilation due to velocity, general relativity predicted a time dilation would also occur due to differences in gravitational field potentials. For instance, an object on the earth's surface would age slower than an object high in the

as the most famous failed experiment due the ironic disproval of aetheres existence and subsequent suggestion of a constant speed of light.

While Einstein's special relativity predicted time dilation due to velocity, general relativity predicted a time dilation would also occur due to differences in gravitational field potentials. For instance, an object on the earth's surface would age slower than an object high in the earth's atmosphere. Both time dilation effects were proved in 1971 when Joseph Hefele and Richard Keating observed the differences in elapsed time between highly accurate cesium atomic clocks which were placed in airplanes and an identical stationary reference clock. Even today, satellite systems must take the effects of time dilation into account in order to provide accurate data. For example, satellites in the Global Positioning System constellation age faster than objects on the Earth's surface, gaining roughly 38 microseconds each day.

Einstein's theories of relativity revolutionized the way we understand time, but like the classical physics developed by Isaac Newton, a fundamental component of how we perceive time was still unexplained: the arrow of time. Einstein had showed that time was strongly entwined with the three spatial dimensions we are familiar with, but there were still differences. Whereas the spatial dimensions contained no arrow and an object can travel freely in any direction, the dimension of time only allows forward travel, with a clear separation between what we understand as the past and the future. Both Newton's theories of classical physics and Eintstein's theories of relativity are time-symmetric, meaning they don't distinguish between the past and future, and fail to explain why events always unfold in one direction, but never the reverse.

We see such occurrences in our everyday lives. The classic example in much scientific literature is a cup falling off a table to smash on the floor. Though equally valid and possible according to Newton's and Einstein's theories, the broken pieces of the cup never gather themselves up and form a complete unbroken cu