Gravity causes time dilation, according to the theory of general relativity. In general relativity, gravity is not viewed as a force acting between objects but rather as the curvature of spacetime caused by mass and energy.
According to this theory, massive objects like stars, planets, and black holes curve the fabric of spacetime around them. This curvature affects the motion of objects and the passage of time in their vicinity. In regions with a stronger gravitational field, spacetime is more severely curved, leading to significant time dilation effects.
The presence of a massive object causes a distortion in spacetime, and as a result, the geometry of spacetime near the object is altered. This curvature of spacetime influences the behavior of light, matter, and also the flow of time.
As an object moves in a gravitational field or experiences gravity, the local flow of time for that object is affected. The closer an object is to a massive body, the stronger the gravitational field, and the more significant the time dilation effect becomes.
In a sense, we can say that gravity causes time dilation because it is the curvature of spacetime caused by mass and energy that leads to the observed time dilation effects. The greater the gravitational field, the more pronounced the time dilation. This has been confirmed through various experiments and observations, such as the gravitational redshift of light and the time dilation experienced by clocks in different gravitational potentials.
So, in summary, gravity causes time dilation by curving the fabric of spacetime, and the strength of the gravitational field determines the magnitude of the time dilation effect.