intergalactic space at 3 K? (Score 3, Interesting)

Intergalactic space is not at 2.7 K. Especially in galaxy clusters, the temperature of the intergalactic medium is often millions of degrees Kelvin. Even in more remote places far from galaxy clusters, it's still much warmer than 2.7 K. The 2.7 K figure is the temperature associated with the cosmic microwave background radiation, not the intergalactic medium.