The Next Emanation was what the Vhnori believed to be their afterlife.
The Vhnori believed that death was just another stage of their existence, that they would evolve to a higher level of consciousness upon arriving there, and that all their questions would be answered. They were told they would see beautiful sights with new eyes and a newly gained greater understanding of the universe.
They furthermore believed that they would go to another dimension, where their deceased loved ones would be present when they entered the Next Emanation, and that they'd be able to talk to them.
As part of their transference ritual, the Vhnori would place their dying into a cenotaph, the purpose of which was to terminate their life just before the appearance of a subspace vacuole. They believed this would allow their body to be taken to the Next Emanation.
In reality, they were taken to the ring system of another planet, where the bodies decayed. In 2371, when Harry Kim of the USS Voyager was accidentally drawn through a cenotaph to the Vhnori homeworld, exposing the Vhnori to this information. This information caused many Vhnori, not only in the scientific world but also among the wider community, to doubt the reality of their afterlife.
Harry Kim pointed out that he only saw corporal remains, still technically allowing for a continued existence as a higher consciousness. Furthermore, Voyager's readings showed that the corpses released neural energy, which persisted in the planet's ambient electromagnetic field. The energy was unusually dynamic, with high variation, pattern complexity, and quantum density. However, this conflicted with the Vhnori disbelief in spirit existence, and their belief that they would instead re-appear as physical beings with arms and legs. (VOY: "Emanations")