system
Given the following post, respond as if you're commenting on Reddit:
human
To reach speed of light you need crazy amount of energy so Does light actually travels with the speed of light or slightly less?
gpt
This is the speed light travels at.

For an object with non-zero mass, it would take infinite energy to get it to the speed of light, which is one way to understand why that can't happen.

But for photons (the particles of which light is made), things are different.  Photons have no mass, which turns out to mean they always have to travel at the speed of light. From the moment they are created to the moment they are observed, they travel at the speed of light.