  The Cosmic-Ray Extremely Distributed Observatory (CREDO) is an infrastructure
for global analysis of extremely extended cosmic-ray phenomena, so-called
super-preshowers, beyond the capabilities of existing, discrete, detectors and
observatories. To date cosmic-ray research has been focused on detecting single
air showers, while the search for ensembles of cosmic-ray events induced by
super-preshowers is a scientific terra incognita - CREDO explores this
uncharted realm. Positive detection of super-preshowers would have an impact on
ultra-high energy astrophysics, cosmology and the physics of fundamental
particle interactions as they can theoretically be formed within both classical
(photon-photon interactions) and exotic (Super Heavy Dark Matter particle decay
and interaction) scenarios. Some super-preshowers are predicted to have a
significant spatial extent - a unique signature only detectable with the
existing cosmic-ray infrastructure taken as a global network. An obvious,
although yet unprobed, super-preshower 'detection limit' would be located
somewhere between an air shower, induced by a super-preshower composed of
tightly collimated particles, and a super-preshower composed of particles
spread so widely that only few of them can reach the Earth. CREDO will probe
this detection limit, leading to either an observation of an as yet unseen
physical phenomenon, or the setting upper limits to the existence of large
extraterrestrial cascades which would constrain fundamental physics models.
While CREDO's focus is on testing physics at energies close to the Grand
Unified Theories range, the broader phenomena are expected to be composed of
particles with energies ranging from GeV to ZeV. This motivates our advertising
of this concept across the astroparticle physics community.
