The transmission of electromagnetic waves through space (a vacuum) does not result in a loss of energy because electromagnetic waves do not require a medium to propagate. In a vacuum, there are no particles or matter to interact with or absorb the energy of the electromagnetic waves. This property is a fundamental characteristic of electromagnetic waves.
Electromagnetic waves consist of oscillating electric and magnetic fields that are self-sustaining. The changing electric field induces a magnetic field, and the changing magnetic field, in turn, induces an electric field. This interplay between the electric and magnetic fields allows the wave to propagate through space.
In a vacuum, the electromagnetic waves can travel indefinitely without being attenuated or losing energy. The energy carried by the waves remains constant over vast distances because the fields continuously regenerate themselves as the wave propagates.
However, it's important to note that the intensity of an electromagnetic wave can decrease as it spreads out over a larger area. This decrease in intensity follows the inverse square law, which means that the energy is distributed over a larger surface area as the wave expands. So while the energy is conserved, the power density (energy per unit area) of the wave decreases as it spreads out.