Why can't perpetual motion machines work and what are the fundamental laws of physics that prevent their existence?

Perpetual motion machines cannot work because they violate the fundamental laws of thermodynamics, specifically the first and second laws. The first law states that energy cannot be created or destroyed, only transferred or converted. The second law states that in any energy transfer or conversion, some energy is lost as heat, making it impossible to achieve 100 efficiency. This means that a perpetual motion machine, which would continuously generate energy without any input, is not possible within the constraints of these laws.