3 ms·

> it is void Space is not a complete vacuum.

• henearkr 9y ago
  Yeah, but sufficiently so that most photons are not encountering any other things on their way.
  • Nomentatus 9y ago
    Not clear - have you taken virtual particles into account?
• henearkr 9y ago
  Well, actually it seems you are true. There are absorption rays for the inter-galactic medium, as shown in: https://ned.ipac.caltech.edu/level5/Madau6/Madau2.html https://ned.ipac.caltech.edu/level5/Madau6/Madau2.html So, please ignore my previous reply ↓