For example Ben Bova in Blood Music posited the idea that you could have nanobots that replicated like crazy and each had a high density. He then took it one stage further and took the idea that the universe is defined by observation (a riff on the heisenberg principle) and suggested that with enough intelligence packed into a single area (trillions of intelligent beings in a tiny space - nanobots after all) that the laws of physics become mutable according to that intelligence.

Whilst Occam’s razor would say that’s a barrel load of fluff, given a sufficiently long time scale and the fact we don’t *know* it’s not right, the chances of it being *possible*, in some shape or form, become quite high (over a long enough time scale). As a result throwing things out because they don’t match the laws of physics as we know them today isn’t sensible
After all at the end of the day, the idea was to suggest that certain capabilites were possible, then see how that modifies some scenarios, and then figure out what you need to do today to achieve a semblence of those scenarios. (After all if I’d suggested Ben Bova’s nanobots in the session, how would that have changed the luggage ? )