system
Given the following post, respond as if you're commenting on Reddit:
human
What happens to the light/energy that's travelling faster than the universe is expanding?

Energy can't be destroyed, the speed of light is 3,000,000m/s, and the universe is expanding at around 70,000m/s. 
Given those facts, light must constantly be travelling past the edge of the universe; what happens to it?
gpt
Where did you get this number? The universe doesn't actually have a speed of expansion! What happens is that the velocity in which two points "expand" away from each other is proportional to the distance, and the proportionality factor is given by the Hubble parameter.

No matter how small the Hubble parameter is (it is very small today, so for small scales we don't see expansion), there will always be a distance after which the expansion velocity will be bigger than the speed of light, so the light will be trapped inside this bubble of expanding universe.