The idea was originally formulated by physicist James Clerk Maxwell, but it gained controversy because it appeared to violate the second law of thermodynamics. Put in experimental terms, this law states that when hot and cold water are mixed, they will eventually reach an equilibrium middling temperature.
Maxwell proposed that a hypothetical being (later dubbed Maxwell's demon) could separate the water into two compartments and reverse the process, isolating hot molecules from cold by letting only the hotter-than-average through a trap-door between the compartments.
maxwell demon writes: Researchers at NIST have found out that cheap green laser pointers can emit dangerously intense infrared light. Since you cannot see infrared light, you'll normally not notice it, however it's dangerous for your eye. The article also describes how to test laser pointers with consumer equipment. Of course, while doing that, do not look into laser with remaining eye.