This question has come to me from my friend in fact: he noted that the heating in the pub is painted black. I replied that it's better for heat emission.

I don't know where did I know that from. And he disagreed asking me for a reason why would black emit more heat than white. We could, however, agree on fact, that black absorbs more heat than white.

I quickly created a thought experiment to proof by contradiction that the black must emit more light than white:

Assume that white and black both emit the same amount of light. Put a black and white object in an area. Assume that any light (or heat) emitted by the objects can only be absorbed by them. Imagine that the white object emits light and heat. The black one will absorb considerable amount of it. When the black object emits the light the light one will reflect a great portion of it - which can be then absorbed back by the black one.

Written like this, it seems that second law of thermodynamics is being broken by this concept. However, my friend has also thought something to oppose me:

If black objects emits more heat than the white one, why the black objects are hotter when put in the sun? Shouldn't they emit the extra light they absorbed?

I understand that it's not all that simple. There's an article that says I'm right but it doesn't really satisfy me.

For start, infrared is no color at all - how could it have to do anything with black, white or any other color? Shouldn't an "infrared" painted stuff reflect most heat?

I ask for an answer that sufficiently explains why the black and white things absorb/emit heat as they do. And, if questions post by both mine and my friend's arguments are asked, I will be very happy.

This question has come to me from my friend in fact: he noted that the heating in the pub is painted black. I replied that it's better for heat emission.

I don't know where did I know that from. And he disagreed, asking me: "Why would black emit more heat than white?" I didn't know. We could, however, agree on fact, that black absorbs more heat than white.

I quickly created a thought experiment to proof by contradiction that the black must emit more light than white:

Assume that white and black both emit the same amount of light. Put a black and white object in an area. Assume that any light (or heat) emitted by the objects can only be absorbed by them. Imagine that the white object emits light and heat. The black one will absorb considerable amount of it. When the black object emits the light the light one will reflect a great portion of it - which can be then absorbed back by the black one.

Written like this, it seems that second law of thermodynamics is being broken by this concept. However, my friend has also thought something to oppose me:

If black objects emits more heat than the white one, why the black objects are hotter when put in the sun? Shouldn't they emit the extra light they absorbed?

I understand that it's not all that simple. There's an article that says I'm right but it doesn't really satisfy me.

For start, infrared is no color at all - how could it have to do anything with black, white or any other color? Shouldn't an "infrared" painted stuff reflect most heat?

I ask for an answer that sufficiently explains why the black and white things absorb/emit heat as they do. And, if questions post by both mine and my friend's arguments are asked, I will be very happy.