  A large number of particle species allows to formulate quantum gravity in a
special double-scaling limit, the species limit. In this regime, quantum
gravitational amplitudes simplify substantially. An infinite set of
perturbative corrections, that usually blur the picture, vanishes, whereas the
collective and non-perturbative effects can be cleanly extracted. Such are the
effects that control physics of black holes and of de Sitter and their
entanglement curves. In string theory example, we show that the entropy of open
strings matches the Gibbons-Hawking entropy of a would-be de Sitter state at
the point of saturation of the species bound. This shows, from yet another
angle, why quantum gravity/string theory cannot tolerate a de Sitter vacuum.
Finally, we discuss various observational implications.
