Every technology related to the Π bomb or the Π cell is an application of portals between timelines.

The basis of the system is conceptually simple: it is possible to create a localized bending of spacetime such as two or more timelines intersect in a particular moment and place; when this happens you get a “warp” effect around the intersection where physical properties are slightly off, and an actual “hole” in reality in the center. This hole is usually an irregularly-shaped mess of totally reflectant globules that are not affected by gravity; instead they drift around existing matter.

They make a very specific sound that doesn't seem to transmit through air but through spacetime itself vibrating. If you have any measurement instruments running (from voltmeters to a simple compass) where you hear the sound you will often notice their measurements fluctuating alongside the sound.

Any matter that touches the actual rift will usually suffer severe damage, depending on the places and times being connected. For most portals, the other side is empty outer space so you risk explosive decompression, being bathed by radiation, losing all heat as it radiates into space, etc. Some other portals can connect to physical matter, in which case you end smushed inside a rock; or more commonly inside a star, in which case you are instantly reduced to atomic plasma, which you wouldn't get to experience because the plasma coming from the other side would reduce you to ashes first.

The most dangerous case is connecting to a timeline that's indistinguishable from yours, in which case the you from the other side and the you from this side occupy the same space at once, causing every single subatomic particle to be annihilated. This last one is the basis for a Π bomb and actually the easiest to achieve because reaching timelines more different requires incrementally more energy.

Additionally, natural portals are not fixed: they drift in both timelines that they are connecting, so any object that enters one is twisted in at least five different directions, and the smaller and more irregular the portal, the more objects might be shredded. A portal can be stabilized though, and then it takes the shape of a perfect sphere, hovering in place. Only then does it become safe to enter it.

Since portals twist spacetime around the contact area, things around it might not exactly work as they would usually. This includes all technology, starting up from the most delicate machines and working up to the simplest ones, and biological systems that are actually molecular machines. The only reason living beings might survive longer in an affected area than machines is that they possess many internal redundancies, but an analysis of any living being that has been exposed to portals for a long time will reveal many kinds of damage and internal changes.

An important thing to note: there's really no such thing as “Π radiation”. Portals do not radiate a specific and unique energy type. They radiate whatever gets in from the opposite side, and that can be anything, but you can use measurement instruments to find unstable portals by checking for unexpected fluctuations of signals that should be constant: compasses will waver, voltmeters will skip, and even geiger counters can produce weirdly arrhythmic signals.

Portals are not the cause of spacetime bending, they are caused by spacetime bending, and spacetime can bend for any of a number of reasons. This can happen in a extremely wide area, spanning several timelines, which will cause a “portal storm season” where portals can appear randomly. This followed the creation of all zones in the Rigasian Timeline as well as the first battle of the Rigasia/Kesizma War.