What is phrase for State of intellectual seclusion from real world?

There isn't one perfect phrase that captures the exact meaning of "state of intellectual seclusion from the real world," but here are some options depending on the specific nuance you want to convey:

General terms:

* Intellectual isolation

* Mental withdrawal

* Cognitive detachment

* Philosophical retreat

* Ivory tower (a metaphorical term for an environment where intellectual pursuits are prioritized over practical concerns)

More specific terms:

* Academic bubble (for seclusion within a university or academic setting)

* Hermetic existence (emphasizes self-imposed isolation and focus on intellectual pursuits)

* Solipsistic state (implies a belief that only one's own mind is real, with a disconnect from external reality)

* Existential isolation (suggests a profound feeling of separation from the world and its concerns)

Figurative language:

* Living in a world of their own

* Lost in thought

* Dreaming of a different reality

* Escaping the mundane

The best phrase for you will depend on the specific context and the level of intensity you want to convey.