I was thinking recently about what might happen if you were to place a block of material in the middle of a complete vacuum. Obviously there's not going to be a way to ever achieve such a scenario but what would happen if you were to put a block of let's say steel at 100C in a vacuum such that the block is not in contact with any material connected to the containment and have it such that outside energy is minimized. I assume the block would lose heat/vibrational energy but what would be the mechanism for such an energy loss and what time scale would it take for the block to reach let's say 0C?
Let me know if there's anything I can add to make the question more clear.