Scientist noticed that the universe is expanding, possibly due to a massive explosion. Maybe when God said let there be light there was a brilliant flashy explosion of light and the pieces became the sun, moon, stars and earth. Ever since then light has been traveling outward at light speed expanding our universe.

Hopefully the light increases in our souls daily as we exist. Much like the kingdom of God which will forever increase.

(and of the increase of his kingdom there will be no end.)