Free is not a problem here, because we&#x27;re talking &quot;free&quot; in economical sense. Thermodynamics does not need dollars to exist. Society has been dealing with (economically) free since long before the invention of money. Things like doing one a favour, or giving away for public good, means free on the receiving end.<p>And before someone mentions reciprocation - yes, it exists, but it always works <i>implicitly</i>. If you expect an explicit reciprocation, then you&#x27;re doing trade and not a favour.