Ghosts and the Laws of thermodynamics

Zeroth Law – If two systems are in thermal equilibrium with a third, they are in thermal equilibrium with each other. It’s called the zeroth law because it was thought of after the other three and is more fundamental, so instead of renumbering the other three, it was called the Zeroth Law.

First Law – Energy can be neither created nor destroyed; it can only change forms. This also means that, for an isolated system, the total energy remains constant.

Second Law – No engine or refrigerator, working in a cycle, is 100% efficient. This usually means that energy is lost to heat in any system, and you can never get back all the energy you put in. It also states that Entropy (Energy that cannot do work) must never decrease.

Third Law – You cannot reach absolute zero. As temperature approaches absolute zero, the entropy (or disorder) of a system approaches a minimum. This also means that you can't create order (reduce entropy) by adding energy to a system; the system must spend energy to reduce local entropy and become more organised.

The British Scientist and author C.P. Snow coined the following ways of remembering the laws:
1) You cannot win (that is, you cannot get something for nothing, because matter and energy are conserved).
2) You cannot break even (you cannot return to the same energy state, because there is always an increase in disorder; entropy always increases).
3) You cannot get out of the game (because absolute zero is unattainable, you must always obey the laws of thermodynamics).

If ghosts were formed of energy and not matter, they would lose energy because of the second law of thermodynamics. Therefore, it would be impossible for them to maintain their structure and order for any significant period of time. If they interacted with the world, they would move themselves or other objects, and perhaps emit light or sound. Hence, due to the First and second laws, they would fade out of existence. Haunted Houses are popularly conceived with so-called regular hauntings, but this is impossible since the ghost would lose energy and disappear from existence. The only way to make haunting possible would be for ghosts to draw energy from the environment in order to sustain their existence.

Entropy is also against ghosts; a system will not become more ordered if energy is put into it. It actually needs to spend energy to become more ordered; otherwise it will naturally follow disorder. For example, a room will become messier unless someone spends energy tidying it. Hence, spontaneous organisation of matter or energy to form an otherwise formless ghost would require spending energy. Ghosts, if they existed, must be made of energy; then they must spend energy in order to appear, so again they wouldn’t last for long. But where does energy come from in the first place? The First Law of Thermodynamics states that energy cannot be created; it can only change form. Again, a ghost would need a source of energy, which means taking it from somewhere else; this would be detectable, but has never been seen.

The principle of the conservation of energy and the fact that entropy always increases are so fundamental that it would require very solid evidence before you could throw it away. If you saw a ghost, you'd have to rip the book up; I suggest it would be far more surprising that thermodynamics was BS than that ghosts actually exist. Ghosts are not consistent with scientific understanding of the physical world; as such, they only exist in fantasy land.

These scientific facts will never convince ghost believers, since they are certain ghosts are an exception to the laws of thermodynamics. This is the very definition of pseudoscience, as it is not just disconnected from reality; it directly opposes it. It is far more likely that these believers are deluded or mistaken than that ghosts actually exist. Aside from the fact that ghosts violate the laws of nature, there is also the massive problem that no compelling evidence exists for their existence. Hence, we can say with certainty that they do not and cannot exist.