Perpetual motion machines are impossible. They violate the fundamental laws of Thermodynamics: energy cannot be created or destroyed, only transformed from one state to another; some energy is always wasted. Even so, now and then someone appears with another version of a perpetual motion machine.
The modern version of the perpetual motion machine is creating value out of nowhere. Alex Tabarrok writing in Marginal Revolution:
Imagine that I own a house and I create a million [crypto]coins representing the value of the house. I give half of the coins to my wife. I then sell one of my coins to my wife for $10. Now the house has a nominal value of $10 million dollars and my wife and I each have assets worth $5 million. Of course, no one is likely to buy my house for $10 million or lend me money based on my coin wealth but suppose I now get my friend Tyler to buy a coin for $15. Tyler says why would I want to buy your s!@# coin! To encourage Tyler to buy I give him a side-deal that is not very public. Say an extra 5% of our textbook royalties. Tyler buys the coin for $15. Now the coins have gone up in value by 50%. My wife and I each have $7.5 million. Other people may want to get in while they can—Tyler bought in! Are you in? I’m in!
As Tabarrok points out, “much of this story is familiar. The assets involved were crypto tokens but they could have been fiat currencies, internet stocks, or mortgage-backed securities.”
A general understanding of thermodynamic laws as a mental model is a very useful asset. The abbreviated version is there is no such thing as free lunch.