[woopsn]

There are no streaks of gamma radiation (or any sort) going across the Milky Way connecting the stars.

The second issue is less obvious - the Milky Way is some 13 billion years old, has hundreds of millions of stars, but is only 100,000 light years across. Fact - the technological limitations of "today" (this century, this mya), are with empirical certainty not relevant.

Interstellar voyage is not amenable to the time preferences and capabilities of the great ape. The only stuff that could transport life across the galaxy does so slowly and without propulsion.