system
Given the following post, respond as if you're commenting on Reddit:
human
How small of a hole can light shine through?

Can it shine through a hole that is one atom wide?
gpt
Generally speaking, you would want a hole to be at least the size of the wavelength of light (about 500nm for visible light) in order to transmit light.  It is possible to transmit light through smaller holes, but usually extraordinary measures need to be taken to do this.  

In your day to day life, your microwave has a metal screen that blocks the microwave light from exiting the oven.  You can see how big the gaps are, but the microwave light can't get through.