What if the first law of thermodynamics was true, but the second law was not? How would the world be different

You'd be able to transform heat with amazing efficiency into work and then back to hear without any loss.

Because of the second law of thermodynamics, we know that in reality every time we convert from one form to another, the energy becomes of a less useful type and you can't really reuse that less useful form of energy (such as heat). You can use heat to transform it into useful energy, but not nearly as efficient as converting from an organized form of energy like fossil fuels or uranium.



How would the world be different? We would be able to make cars that don't require refilling as energy would be transformed from heat to work continuously without any dissipation.

To put it simply, all energy exchanges would be completely equal, and the world's fuel problems would be invariably solved. This is hypothetical, of course.