The testimony of other conscious observers may be helpful, but it is ultimately up to one's own "observer".
I see reality in this fashion:
Imagine a flat sheet of fabric, made of interwoven fibers. Embedded in this sheet exists multiple lights. Streaming from each light are the fibers of the sheet, intersecting with other fibers emanating from other lights.
I see the sheet as representing (illusory) reality. The "lights" represent multiple individual conscious observers in that reality. Observers, craving "reality", both create and are attached to the fibers (kamma/karma) of existence. The fibers represent strings of created reality, the Creator being each individual observer. Where a "fiber" intersects with a "fiber" emanating from another observer, an illusory "independent" object in illusory reality is created.
The more attached (craving) an observer is to this illusory "reality", the more entangled he becomes in the "fabric" of illusory reality. Transcending the illusory reality involves cutting the fibers of kamma, freeing the conscious observer. The process of "cutting" the fibers destroys one's own fibers from illusory reality, destroys his version of reality (his universe) as he knows it, with the result of collapsing all of reality as far as he is concerned.