The Partial Displacement effect is currently being observed between SP Creatures and Human born entities. This effect allows for both the creatures and humans to be located in more than one place at the same time, but only through psychological means. One instance of the entity is always physically hooked in their "main" location. This prevents an SP creature to fully and physically be present on Earth, and a human in SP.
Due to the master sync, SP creatures only see the world outside of SP through their human observer. Due to this, distant space travel is currently not possible at the time, and neither is being able to find the direction to Earth from any point in SP. This is why they are not able to physically come down to Earth. However, the creatures can psychologically tether to their human creator and be present in the area around them. Unlike humans, the SP creatures are able to physically disappear from SP while doing so, but their physical state on Earth is somehow not fully rendered. Mentally however, they are fully present.
In terms of humans, the partial displacement is very similar. When a human goes to SP, they are able to be physically present in SP, but they are tethered to Earth at the same time, causing a slight conflict of senses. The human is able to see SP and the creatures, use all their powers in SP, and so on; however they also see with their eyesight on Earth at the same time as if they are getting two feeds. Interference with their main tether to Earth will temporarily disconnect them from their instance in SP.
Because full displacement is not possible, humans (especially M.O.G.) cannot travel to SP fully, or use any SP given powers back on Earth. For a human to be fully empowered, both their human instance and SP instance must be one. As for SP creatures, partial displacement makes it so that they are invisible and intangible on Earth, and are not able to be seen or observed in any way by anyone but their creator.
A fix from partial displacement into full displacement is very important, and one of the priority research topics of the SP creatures. Once full displacement is possible, creatures and humans (even non SP humans) will be able to physically interact and observe each other, bringing the bridging of SP and everything outside of it half way closer.