I've posted about the following before but it doesn't seem like anyone remembers the programme which was in monochrome on TV?

The story went that we on Earth had made contact with an alien craft (or vice-versa) and the alien technology enabled us to  talk to them. Eventually we directed them to a safe landing spot (I think it was an airfield). The craft landed and we were asking where they were as we couldn't see them. A view from inside the alien craft depicted what looked like an oozy substance and then a gigantic creature wriggled past. The aliens were crying out that we'd deceived them.

One of the principal scientists went out looking for them as he knew they were out there somewhere and he thought they might be invisible. Suddenly, everything from the craft disappeared = silence.

What had actually transpired was that the aliens and their craft were just up in size from being microscopic and they'd landed on a muddy (air)field and the gigantic creature was an earthworm. When the aliens were silenced, what had happened was the scientist looking for them had trod on the tiny craft and destroyed it.

Now we see in many sci-fi programmes and films that there are enormous mother craft moving at terrific speed through inter-stellar space with human-sized occupants but it may well be that "intelligent life" might evolve to become really small and therefore wouldn't it be far easier for much smaller craft to leave their home planet, exist in space and eventually visit planets in far distant solar systems?