Warning: contains spoilers for Fantastic Four #31
The Fantastic Four have just - quite literally - solved every single problem in the Marvel Universe at once. Within the first few pages of Fantastic Four #31, by writer Dan Slott, artist R.B. Silva, and colorist Jesus Aburtov, Reed Richards and Ben Grimm stumble onto a solution past the Forever Gate that makes solving the world's problems a trivial matter. The device has the possibility to show Reed and the rest of Marvel's first family a near-infinite number of destinations...and they found the most important one on their first trip.
At the crack of dawn, Reed Richards invites Ben for a quick trip through the Forever Gate. The duo leaves their families behind for some much-needed bonding time after the events of the King in Black crossover. This levity is especially necessary after Ben had just heard his future self admit that Reed will one day die at his hands in Fantastic Four #29. Reed is ecstatic to use the Gate for the first time, eager to explore new realms that could hold the key to crucial questions on Earth. The two don spacesuits and leap through the gate, where they discover a realm that can instantly solve any problem they encounter: the dimension of Thoughtspace.
Reed immediately finds himself in a void surrounded by abstract geometric shapes. Scanning the area, Reed is stunned. "The data I'm collecting...it's astounding! ...Everywhere I look, each new phenomena is an answer to some theoretical question that has plagued Earth's greatest minds for centuries!" Ben is somewhat bored, and wonders out loud that a standard monster-of-the-week should have appeared by now. As if on cue, Ben and Reed are surrounded by alien creatures that attack the duo on sight. A fight ensues and Reed realizes the dimension to which they've traveled manifests thoughts into reality. Monsters appeared because Ben thought of monsters. In the same vein, Reed found answers to scientific questions because he willed them into existence. Thoughtspace turns thoughts into reality - even if the object in question does not yet exist in reality.
The discovery of Thoughtspace and the properties therein essentially means - with no exaggeration - that Reed has solved every problem in the universe. With the power of his mind, Mr. Fantastic can think of a cure for cancer, and it will appear in his hand. Even the climax of the adventure proves that complex machines, willed into being via thought, can function perfectly: Reed is locked out of returning home through the Forever Gate...so he simply thinks of a new one. Instantly, the new Gate is manifested and Reed and Ben jump through, avoiding the monsters and arriving safely on Earth.
Thoughtspace is not without its dangers. In addition to the monsters summoned, Ben inadvertently manifests a vision of his future self murdering Reed, just like the future Thing had stated. Ben (still unaware of the reason why he would ever do such a thing) is disturbed by the vision, and perhaps even more so that he can't stop thinking about it. But the existence of Thoughtspace opens up a world of new possibilities for the Fantastic Four and for the Marvel Universe as a whole. If Reed and Ben can control their minds, they could easily return to the Thoughtspace dimension and solve millions of problems in a single afternoon...and if they're not careful, create just as many.