Things spread out due to various factors, primarily driven by differences in energy, concentration, or pressure. For instance, in thermodynamics, heat causes molecules to move faster and spread apart. In diffusion, substances move from areas of higher concentration to areas of lower concentration, resulting in an even distribution. Additionally, forces such as gravity or wind can also contribute to the spreading out of materials.
it isn't spread, it develops from other causes
A concave mirror causes light to converge to a focal point, while a convex mirror causes light to diverge and spread out.
When one part of a vibration causes air particles to spread out, they form ararefaction
That's how they spread their seed.
rising molten magma
When one part of a vibration causes air particles to spread out, they form ararefaction
The shortening in them melts and causes them to spread.
the spred of bactriea is caused by sickness
foam
Malaria
Convection currents
The motion of the water molecules eventually causes the flavor to spread.