No, gravity is not an illusion caused only by time dilation. Gravity is a fundamental force in the universe, and its effects go beyond just time dilation.
In the theory of general relativity, gravity is described as the curvature of spacetime caused by the presence of mass and energy. According to this theory, massive objects like planets, stars, and black holes cause a curvature in the fabric of spacetime. This curvature influences the motion of other objects in the vicinity, causing them to move along curved paths.
The effects of gravity can be observed in various phenomena, such as the motion of celestial bodies, the behavior of light around massive objects, and the formation of structures in the universe. For example, gravity governs the orbits of planets around the Sun, the motion of galaxies within galaxy clusters, and the bending of starlight as it passes near massive objects.
Time dilation is one of the consequences of general relativity and is intimately connected to gravity. In regions of strong gravitational fields, time runs slower relative to regions with weaker gravitational fields. This phenomenon, known as gravitational time dilation, has been observed and verified experimentally in various ways, including the use of atomic clocks.
While time dilation is a significant effect of gravity, it is not the sole cause of gravity. Gravity is a fundamental force resulting from the curvature of spacetime caused by mass and energy, and it has various observable effects beyond time dilation.