The Cosmos And A Cat

In Poul Anderson's "The Horn of Time the Hunter," a relativistic spaceship explores the fringes of the galactic nucleus and returns over ten thousand years later.

"'It is even recorded, many thousands of years ago, that our fleet went off to explore the far side of the galaxy.'
"'But that's an enormous journey. How long did it take?'
"'At the speeds we can achieve today, it would take twenty thousand years,' answered Rigel.
"'Incredible. It still amazes me that this ship can achieve a velocity close on a fifth the speed of light. No Earth person would have conceived ten years ago that this would be possible. It's a completely new dimension of space technology.'"
-Into Deepest Space, 5, p. 59.

Fred Hoyle never has FTL. Anderson's and the Hoyles' figures seem to agree:

galactic nucleus round trip, ten thousand years;
far side of the galaxy round trip, twenty thousand years.

In Anderson's Tau Zero, a relativistic spaceship traverses vast volumes of dark space between scattered groups of groups of galaxies until the universe contracts and re-expands. In Into Deepest Space, the concluding chapters, which I have yet to reread, are entitled:

12 Out of the Galaxy into Deepest Space
13 The Quasar
14 Transfiguration

Thus, it seems that the Hoyles' spaceship embarks on a similar journey but reaches its transcosmic apotheosis more quickly. However, my immediate agendum is to return to Anderson's Operation Luna, where we left the cat, Svartalf, absorbing sunlight like a rug. See here.