For the energy fairy believers...
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Perpetual nonsense
$this->bbcode_second_pass_quote('', 'T')he first law of thermodynamics—essentially a restatement of the conservation of energy—deals with energy, work and heat. A machine needs energy to work or else it just sits there doing nothing. If it is to be useful, it can do one of two things with the energy put into it: perform work or generate waste heat—or, in the real world, a bit of both. That means the energy input has to equal the output of work and waste heat. In short, the energy of the total system is conserved.
The second law of thermodynamics is more subtle still. It is built around the concept of entropy—a measure, if you will, of how energy gets dispersed. It can be thought of as nature’s instinctive tendency towards disorder. In other words, it defines the irreversibility of processes involving heat and energy.
Thus, according to the second law, a process can occur only if it increases the total amount of entropy involved. It also means that heat cannot flow from something that’s cold to something that’s hot—that is to say, heat flows only along an irreversible one-way street. Most crucially, the second law makes it clear that heat cannot be converted completely into work. Some of the thermal energy has to be passed on to something at a lower temperature. The implication is that any device that needs energy to work can never be 100% efficient.
By their very definition, perpetual-motion machines are required to be at least 100% efficient. Thus, to continue running indefinitely, they violate either the first law (by promising something for nothing instead of merely conserving energy) or the second law (by implying that they convert all their energy into work). And that’s nonsense. Remember: the first law says the best you can do is break even, while the second law adds, forget it, you can’t even do that! Keep those two principles in mind, and you’ll never go far wrong.
