Above and Below
All of the observable universe is filled with large numbers of photons, the so-called cosmic background radiation, and quite likely a correspondingly large number of neutrinos.
The current temperature of this radiation is about 3 K, or -270 degrees Celsius.
A vacuum is a volume of space (empty space) that is essentially empty of matter, so that gaseous pressure is much less than standard atmospheric pressure.
A perfect vacuum with a gaseous pressure of absolute zero is a philosophical concept that is never observed in practice, not least because quantum theory predicts that no volume of space is perfectly empty in this way.
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Still begs the question what is outside the observable universe.
Laser-cooling Brings Large Object Near Absolute Zero from MIT
LHC cooler than outer space by John @ Cosmic Variance