One common misconception spread by an unclear discussion of the nature of relativity and other physics related to time is that time does not, in fact, exist at all. This comes across in a number of areas that are commonly classified as pseudoscience or even mysticism.
Time is actually an integral part of the universe and the very linear concept of time is tied into the concept of the Second Law of Thermodynamics. Without time as a real property of the universe, the Second Law of Thermodynamics becomes meaningless.
What Einstein proved, through his theory of relativity, time by itself was not an absolute quantity. Rather, time and space are united in a very precise way to form spacetime, and this spacetime is an absolute measure that can be used to determine how different physical processes in different locations interact with each other. This does not mean that everything is happening simultaneously, however. In fact, Einstein proposed the idea that no information can travel faster than the speed of light. Every point in spacetime is limited in the way it can communicate with other regions of spacetime.
The Arrow of Time and Entropy
The phrase “the arrow of time” was coined in 1927 by Sir Arthur Eddington and basically, it is the idea that time flows in only one direction, as opposed to dimensions of space which have no preferred orientation.
Eddington makes three specific points in regards to the arrow of time:
1. It is vividly recognized by consciousness.
2. It is equally insisted on by our reasoning faculty, which tells us that a reversal of the arrow would render the external world nonsensical.
3. It makes no appearance in physical science except in the study of organisation of a number of individuals. Here the arrow indicates the direction of progressive increase of the random element.
The distinguishing factor of the arrow of time is that it points in the direction of increasing entropy, per the Second Law of Thermodynamics. Things in our universe decay as a course of natural, time-based processes – but they do not spontaneously regain order.
The curious thing is that the laws of physics are “time reversible” … which is to say that the laws themselves look as if they would work perfectly well if the universe were played in reverse. From a physics standpoint, there’s no real reason why the arrow of time should by necessity be moving forward. The most common explanation is that in the very distant past, the universe had a high degree of order (or low entropy). Because of this “boundary condition,” the natural laws are such that the entropy is continuously increasing.
Read the original story: http://physics.about.com/od/timetravel/f/doestimeexist.htm
Entropy explanation and example:
Image source: http://www.scientificamerican.com/media/inline/AB230924-FA4D-9EAC-5E5E8D5152C227B1_3.jpg
While physicists don’t necessarily have a complete understanding of a concept such as time, it does not mean that it’s valid to say they have no understanding of time, or that they’ve written off the whole concept as unreal. They most assuredly have not.