Take a large round basin of water and introduce running waves on the surface in such a manner that the combination of all waves will establish a standing wave of some sort of pattern, letters of the alfabet, appear above the original surface. The original surface level in between the apperently static figures will be a tiny bit lower as some mass has been moved into another dimension perpendicular to the surface. Water is water, so after removal of the wave generation the surface will rise to its original value. But take the z dimension to be the dimension of mass and the x,y surface the vacuum plane. Raising the water in z direction can only be done in quanta, so that dropping back again will also only occur in quanta. If we look at the height of the crest forming the figure, it appears that this height is a slightly higher as expected if we take that level (from top to bottom) should be a measurement of the total mass. There is a little piece extra we can not get access to because if we try (by removing some of the mass) that bottom level will shift upward and we are below the surface. Could it be that that difference we see, that level of zero-point energy is due to the fact nature took a bit of energy from the vacuum, turned it into mass? If I would try to create a figure (next to a number of other ones) consisting out of a very thin and also very high coumn of water in which almost all the water is contained, the column itself can work as a point source for waves: the oscilators have hardly any water left to exitate and slowly water starts to leak back into the basin . That mass is a complex combination of all kinds of running waves poping out of tiny not connected oscilators, which can only be forced back under immense pressure (decomposed into the running waves again)?