The first sentence of the article "It does something to you when you drive in here for the first time" probably gives you a sense of how worthwhile it'll be reading the rest. If you're looking for a human interest story go right ahead.

The article goes into detail about the experimental setup. According to the article they are going to use cuprates mounted on a balance. The deviations in the balance are going to be read using laser interferometry. They are using cuprates so they can easily switch between a superconducting phase and an insulating phase. This is to measure if the virtual particles have a buoyancy force.

The reason why they want to test this is explained in the paragraphs above it. It also explains why this method was chosen and what the difficulties are.

I have no idea why you would categorize this as a human interest story.

Is it silly for a layman to ask what is the natural density of the vacuum energy?

"Nothing" can be a slippery concept. See for example Robert Lawrence Kuhn's nine levels/types of nothing:

* https://closertotruth.com/news/levels-of-nothing-by-robert-l...

Also various physicists:

* https://blogs.scientificamerican.com/observations/physicists...

The general field of the study of being:

* https://en.wikipedia.org/wiki/Ontology