Galactic internet made possible by star gravitational lensing
  Galactic Internet may already exist, if all stars are exploited as
gravitational lenses. In fact, the gravitational lens of the Sun is a
well-known astrophysical phenomenon predicted by Einstein's general theory of
relativity. It implies that, if we can send a probe along any radial direction
away from the Sun up to the minimal distance of 550 AU and beyond, the Sun's
mass will act as a huge magnifying lens, letting us "see" detailed radio maps
of whatever may lie on the other side of the Sun even at very large distances.
The 2009 book by this author, ref. [1], studies such future FOCAL space
missions to 550 AU and beyond. In this paper, however, we want to study another
possibility yet: how to create the future interstellar radio links between the
solar system and any future interstellar probe by utilizing the gravitational
lens of the Sun as a huge antenna. In particular, we study the Bit Error Rate
(BER) across interstellar distances with and without using the gravitational
lens effect of the Sun (ref. [2]). The conclusion is that only when we will
exploit the Sun as a gravitational lens we will be able to communicate with our
own probes (or with nearby Aliens) across the distances of even the nearest
stars to us in the Galaxy, and that at a reasonable Bit Error Rate. We also
study the radio bridge between the Sun and any other Star that is made up by
the two gravitational lenses of both the Sun and that Star. The alignment for
this radio bridge to work is very strict, but the power-saving is enormous, due
to the huge contributions of the two stars' lenses to the overall antenna gain
of the system. We study a few cases in detail. Finally, we find the information
channel capacity for each of those radio bridges, putting thus a physical
constraint to the amount of information transfer that will be possible even by
exploiting the stars as gravitational lenses
