Why does time appear slower for objects that are traveling faster and faster, according to special relativity?

I'm kind of confused on the concept of special relativity.





Say for example, a person, leaving Earth, travels in a spaceship 75% of the speed of light. When that person is traveling away from Earth, relative to Earth, how does his perspective on the speed of Earth change (if he had an infinitely large microscope that could see Earth from the telescope of the universe)?|||The general premise behind special relativity is that all experiments have shown that no matter the state of motion you are in, the speed of light relative to you remains constant. Special relativity makes an attempt to justify this mathematically by stating that space and time change based upon how fast you are moving in such a way that the speed of light remains constant. Special relativity refers only to the special case in which two objects are moving past each other with a constant velocity. In the case you mention where a person is moving past the Earth very fast, time on Earth would be slower than time for the rapidly moving person from the person's point of view.|||what Brian said is good, another way to say it is that as you approach the speed of light time passes slower for you than for someone not moving/on the earth. The reason is a curious thing, as Brian stated it is how we justify the fact that the speed of light is always constant in any frame of reference, another way to say this is that you have a beam of light comming from a flashlight, you are driving and have a way to measure the speed of light with you, driving away from the flash light or towards the flashlight the speed of light from the flashlight is always the same, note this is not ture for any other substance we know of, imagine doing this with a car not a beam of light and you will see(anything with mass can not travel at the speed of light as per special relativity)