How does Isaac Asimov use imagery in Foundation's Edge?

Imagery:

"He did and he could not help his muscles tightening with the effort of will he was exerting—as though he were taking hold of the Galaxy and accelerating it, twisting it, forcing it to spin against terrible resistance.
The Galaxy was moving. Slowly, mightily, it was twisting in the direction that should be working to tighten the spiral arms.
Time was passing incredibly rapidly as they watched—a false, artificial time—and, as it did so, stars became evanescent things.
Some of the larger ones—here and there—reddened and grew brighter as they expanded into red giants. And then a star in the central clusters blew up soundlessly in a blinding blaze that, for a tiny fraction of a second, dimmed the Galaxy and then was gone. Then another in one of the spiral arms, then still another not very far away from it.
'Supernovas,' said Trevize a little shakily.
Was it possible that the computer could predict exactly when stars would explode and when? Or was it just using a simplified model that served to show the starry future in general terms, rather than precisely?
Pelorat said in a husky whisper, 'The Galaxy look like a living thing, crawling through space.'"