Its limitations are those of the physical universe: it won't let you play with some really wild ideas that aren't possible, but are fun to speculate about.

This means I must pay close attention to the writing, but equally so to the scientific background - which sometimes means doing fairly involved calculations.

Of course, the way writers think about those things is almost certain to be affected by their own cultural background, and it would be hard to deny that, for whatever reasons, a lot of SF writers come from Anglo or European backgrounds.

It's easy to imagine ways the future can be ugly and depressing. It's harder, but more worthwhile, to imagine plausible ways we can make it better.

As for sticking strictly to presently known science, I will simply point out that we have already experienced at least two major revolutions in science in this century alone.

Resist the temptation to try to use dazzling style to conceal weakness of substance.

Its limitations are those of the physical universe: it won't let you play with some really wild ideas that aren't possible, but are fun to speculate about.