Interdimensional contact
Interdimensional contact was the term used to describe the passage between universes, namely the prime and mirror universes. () In the mirror universe, this action was referred to as a crossover. () While in another context, Beckett Mariner, of the prime universe, informally described the event as the "mirror universe switcheroo". ()

Following his arrival in the mirror universe, Captain James T. Kirk hypothesized that the ion storm they beamed through was of "such magnitude" that it caused a power surge in the transporter circuits and created a momentary interdimensional contact with a parallel universe, at which moment, those in each universe were transposed with their counterpart in the other universe. ()

According to Intendant , "After the first crossover, we were afraid that others might come to interfere in our affairs. It was decided then that if it ever happened again, we would promptly dispose of anyone who appeared from your side." Later, Kira explained that because the first crossover involved a transporter, "all transporters were redesigned afterwards to make sure the same thing would never happen again." ()

Years later, when Quark and Rom were imprisoned in the mirror universe, Quark attempted to demean the  of that universe by stating that "[i]f you were smart, you'd crossover to our universe and get some pointers from our Garak. When it comes to torture, assassination and sabotage, you could learn a lot from him." ()

Following Shaxs' unexplained resurrection in 2381, Mariner considered such an event to describe his mysterious return. ()

Mirror universe
Events