Speed causes time dilation through the interplay of space and time in special relativity. According to the theory, the speed of light is constant in all reference frames. This means that the laws of physics must be consistent regardless of an observer's relative motion.
As an object moves faster relative to another observer, its perception of time changes. Time dilation occurs because the speed of light is constant and the geometry of spacetime is affected.
To understand this, let's consider an example. Imagine you are on a spaceship traveling at a significant fraction of the speed of light, while someone on Earth observes you. From the perspective of the observer on Earth, they see your ship's clock ticking slower than their own clock.
From your perspective on the spaceship, however, you perceive your own clock as ticking normally. The key point to understand is that both you and the observer on Earth are correct in their observations.
To reconcile these differing perceptions, we need to consider the concept of spacetime. In special relativity, space and time are combined into a four-dimensional framework called spacetime. The relative motion between observers affects how spacetime is experienced.
When an object moves at high speeds, its motion through space affects its motion through time. As the object's velocity increases, more of its motion is directed through space rather than through time. This shift in the balance between space and time is what causes time dilation.
In essence, the faster an object moves, the more its time component "slows down" relative to a stationary observer. This effect has been experimentally verified and has important implications in various fields, such as particle physics and the operation of GPS satellites.
So, speed causes time dilation because it alters the geometry of spacetime, redistributing the object's motion between space and time and resulting in a difference in the passage of time as perceived by different observers.