Voyage of the Space Bubble

The Looking Glass, or Voyage of the Space Bubble, series is a military novel series created by author John Ringo and centering on the creation of trans-space portals known as "looking glasses" (due to their mirror-like appearance) and the effect their discovery and the discovery of things via the portals have on life on Earth and off it. Ringo wrote the first book in the series alone, and has collaborated with physicist and author Travis S. Taylor beginning with the second book in the series.

Source: Wikipedia — Voyage of the Space Bubble (CC BY-SA 4.0)