Science can explain many things which happen in our universe. With the help of mathematics and physical theories science has got that ability. Most of the existing scientific explanations are based on three dimensions that you probably already aware about. Those are Length, Width and Height. Using these three dimensions we can explain a physical object or identify something like distance or volume. Knowledge about this three dimension concept would be enough for an day to day ordinary life. But when you take, life span of an object , molecular mechanics or radioactive decay in to account the crack appears in this concept.
No one can explain how things get old or more scientifically, increasing the disorder in a system, using the three dimension concept. Then the question rises, are there any other dimensions except length, width and height? If we count time as a dimension, it will give answers to lots of questions like this. But many people, including scientists reject to consider time as a dimension. They say that time cannot count as a dimension, because it is not constant. But they should also remember that three dimensions are also not constant. Nothing exist in this world is constant, everything is relative and changing with the time.
Time, the fourth dimension is different from classical three dimensions in various ways. Three dimensions can be detected by sensory organs such as human eye. But time could not be detected by those kind of organs. We can move through space forward and backward. Through the time you can only move forward. Backward movement is naturally restricted within the fourth dimension. For example feather in a river only move downward along with the water and never move upward. But if you give enough force against the flow of water you will able to move the feather upward. In the same way, if you supply the required environment and enough amount of energyin the proper state you might able to move something or even yourself to the past through time.
The challage which lies in front of present scientists is to figure out what is this required environment and what is the proper state and the amount of energy which is required. The day which humans find answers to these questions will be the turning point of human civilisation and it will be the start of a new science era.