  The universe is filled with blackbody millimeter radiation (CMBR),
temperature 2.7{\deg} Kelvin[1]. Big-bang cosmology explains this by the
initial thermalization of photons scattered by electrons[2]. This explanation
requires ad hoc previous existence of photons and thermal electrons. On the
other hand most of the mass of the universe is unknown dark matter3. It
explains anomalous dynamical properties, like that of stars in galaxies[4,5,6]
. Alternatively the anomalies have been explained by adjusting and modifying
well known laws ("Modified Newtonian dynamics"[7]). Here we show that
millimeter black holes (m.b.h.) explain both: the background radiation, by its
partial "evaporation", and the dark matter. Black holes emit blackbody
radiation (Hawking[8] evaporation), and this is what is observed in the CMBR.
Millimeter size black holes emit blackbody radiation at a temperature of
2.7{\deg} Kelvin, and this is the resulting CMBR . Partial evaporation of
~10^30 m.b.h. gives the observed background field of photons being emitted and
absorbed at the same rate by the m.b.h. The number of photons is constant, as
observed. Their temperature decreases with time because the mass of the m.b.h.
(and therefore its size) increases with time (the mass-boom effect[9]). The
total mass of the m.b.h. is the dark matter. Hence dark matter is not so "dark"
after all. Two important cosmological items are here identified by only one
source: millimeter black holes.
