Time reversal and a mirror world are concepts used in physics, but they refer to different phenomena.
Time reversal: Time reversal refers to a theoretical concept in physics where the flow of time is reversed. It involves imagining a scenario where the arrow of time, which normally moves forward from past to future, is reversed, and events occur in the reverse order. In such a scenario, the fundamental laws of physics remain the same, but the sequence of events appears to unfold backward. Time reversal symmetry is a fundamental principle in certain branches of physics, such as classical mechanics and quantum mechanics. While time reversal can be a useful theoretical tool for understanding physical processes, it is important to note that true time reversal in the macroscopic world is not observed in everyday life.
Mirror world: A mirror world, also known as a mirror universe or a parity-violating universe, is a speculative concept that arises in certain areas of theoretical physics. It refers to a hypothetical universe that is a mirror image of our own, but with certain fundamental properties reversed. In this mirror world, the concept of left and right would be interchanged compared to our universe. For example, the mirror world would have left-handed molecules instead of the right-handed molecules that are prevalent in our universe. The mirror world is based on the concept of parity violation, which suggests that certain physical processes do not exhibit mirror symmetry. However, it is important to note that the existence of an actual mirror world remains purely speculative and has not been observed or confirmed in the natural world.
In summary, time reversal involves reversing the flow of time, while a mirror world is a hypothetical universe where left and right are interchanged compared to our own universe. Both concepts are theoretical constructs used in physics to explore various phenomena but operate at different levels of abstraction and have different implications.