Earth-148611, also known as The World Outside Your Window and best known as 'New Universe', was an experiment during the Jim Shooter era of Marvel Comics (1986). Eight new titles were launched in a different reality where life had always been relatively "normal". That is until a White Event--a flash of light in the sky--started creating paranormals.
The Black Event, a turning point in the universe's timeline and story, resulted in the complete destruction of Pittsburgh.
The New Universe crossed paths with Earth-616 in the Starblast event in the pages of Quasar. In it, Quasar travels to, then becomes stuck in, the New Universe. He convinces the bearer of the Star Brand to give him its power so he can get home. Afterward, Quasar believes he has exhausted its power when he in fact accidentally transferred it to his girlfriend, Kayla Ballantine.
At the culmination of Starblast, the Stranger actually transports the Entire Earth of the New Universe from its reality, placing it in orbit around his lab world. The Living Tribunal declares the Star Brand to be a threat to all existing powers of the Universe, and seals it off so that it can never again be interacted with. While the remainder of Universe-148611 presumably remains in place, Earth-148611 is left in isolation orbiting the Stranger's Labworld in Universe-616.
In 2006, the universe was revisited with a series of one-shots and short stories collectively called Untold Tales of the New Universe, which take place prior to the Black Event.
The universe was eventually destroyed by an incursion during an unspecified time. The universe's only surviving resident was Blur who somehow made his way to the universe of Earth-616.
This universe's fate following the restoration of the Multiverse is left unknown.