Bernal and the Idea that Habitats May Serve as bastions of forbidden

Alex Michael Bonnici wrote:

>You can read Bernal's book on line via the following link:
>http://cscs.umich.edu/~crshalizi/Bernal/
>
Pretty short for a book. I would have guessed its a summary or a paper.
Very compressed. Visionary, indeed. Especially for SF.

So the original Bernal Sphere did not rotate.

Did Bernal get in trouble for his communist ideas?

Does anyone know why he claims:
"Even if time and space were made equivalent, to gain a second of the
future would be equivalent to travelling 180,000 miles."
Is there or was there a physical theory that relates time and space
quantitatively?