A stone falls into a pond — near the shore, the ripples are barely visible, while the water churns at the point of impact. The electric field around a charge behaves similarly: close in, it's sharp and tangled, but at a distance it stretches into a smooth wave that carries energy away. Physicists call this distant region the radiation zone. There, the field weakens gradually, like ripples spreading without disturbance.
This simple division helps untangle an old puzzle. A stationary electric charge sits on the Earth's surface. According to Einstein's equivalence principle, gravity is indistinguishable from acceleration. An accelerated charge radiates, so in a gravitational field, it should glow. But in reality, nothing of the sort happens. The key is that radiation requires the far zone, which doesn't arise when a charge simply rests in a gravitational field. Its field remains near-field, like water at the side of a boat that doesn't spread in ripples.
The same logic explains why we detect gravitational waves from merging black holes but can't create them in the lab. Gravitational radiation also requires the far zone. In nature, it's produced by colossal masses moving with enormous acceleration. Man-made sources, even the most powerful, remain in the near zone: their field is too weak and dies out before it can turn into a wave. It's like trying to raise a storm by splashing your hand in a bathtub.
If a charge in Earth's gravitational field did radiate, it would lose all its energy in a tiny fraction of a second and simply vanish from sight.
In Carl Sagan's novel 'Contact,' aliens send a signal using gravitational waves, but they need the energy of an entire star to do it.