The Guardians - R. F. Bruce - Bog

In a reality where magic exists and science reigns supreme, there are the guardians, the presiders of the universe. All but destroyed centuries ago by the god of chaos, the survivors now scour the cosmos in search of mortals capable of wielding aether without the need of spells; they are the ones likely to ascend into new guardians and restore order. On Earth, they found five.
Young Seldin and his friends have no clue of what's soon to become of them, for no human has ascended in half a millennium. However, the universe is unforgiving, and in the guardians' absence chaos has spread with warlike races eager to assert their dominance. The Pulsari is one such race, and they too have their sights set on Earth.