Question: what is the casimir effect? I read it in a scientific article.

That is a tough one to explain! It goes like this: There are certain conditions that electromagnetic fields (eg light) must fulfill when they run into a conductor – they behave as standing waves and must be zero at the boundary of the conductor. Even when there is nothing there (in a vacuum) there are still “quantum fluctuations” present for every possible wavelength.

The Casimir effect occurs when two conductors are placed very close to one another. The number of wavelengths that can fit between the conductors is smaller that the number that can be outside – and the presence of “quantum fluctuations” means that there is more pressure outside than inside – causing a force between the plates even when there is “nothing” there.