Yes, the concept of the fourth dimension is often associated with time dilation. In the theory of special relativity, time is considered as a dimension along with the three spatial dimensions (length, width, and height). This four-dimensional framework is known as spacetime. According to special relativity, the relative motion between observers and gravitational fields can lead to time dilation, where time appears to pass differently for different observers depending on their relative velocities or gravitational potentials.
Regarding your second question, E=mc² is an equation derived from Albert Einstein's theory of special relativity. The equation relates energy (E) and mass (m) to the speed of light in a vacuum (c). In this equation, c represents the constant speed of light, which is approximately 299,792,458 meters per second.
The equation E=mc² states that energy (E) is equal to the mass (m) multiplied by the square of the speed of light (c²). It expresses the equivalence between mass and energy, suggesting that mass can be converted into energy and vice versa. This equation is fundamental in understanding concepts such as nuclear reactions, the behavior of particles at high speeds, and the relationship between mass and energy in the universe.