My dad has been trying to find the title of a short story for ages. According to him, the story goes like this:
A scientist who works on an island manages to create a miniature population with whom he can communicate. As time is proportional to their size, it goes way faster for them than the scientist, which allows the creatures to be able to make inventions humans can't yet.
The scientist, whom the creatures worship as a God, starts asking them to reveal how to make these inventions humans are unable to create. At one point, his miniature people end up developing the transport of wireless energy.
Because of the industrial lobby of the human world, the scientist and his people are under a death threat. He asks the creatures to develop the absolute protection, which they do, but this stops the communication between the scientist and his people. He can only see a grey dome in his microscope.
At the last moment, as missiles have been fired towards the island, a breach opens in the dome. The scientist gets a message from his creatures: they ask for forgiveness as they were not able to reach him anymore until then. He responds that if they want to be forgiven, they must amplify the action of the dome.
In the end, the whole island is covered with an indestructible grey dome that no one can see through.
Some parts might be added by my dad's imagination but if you find anything similar to this plot, we would be really grateful!