Alternate reality

"No! It wasn't a vision or a dream or a hallucination. It was real. Now, I know this is hard for you guys to believe. But I swear to you, the entire time you thought I had disappeared on P3R-233, I was experiencing an alternate reality."

- Daniel Jackson

Alternate realities, or parallel universes, are a concept that stems from Hugh Everett's many-worlds interpretation of quantum mechanics. It is believed that there is an infinite number of different realities, some more similar than others. Sometimes there are the same people, places, and objects, but with notable differences.