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 voltimeters 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 require incrementally more energy.

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.