Hello Markus and Abir,

Since you both had similar questions about the active and passive forces mentioned in Baha’u’llah’s Tablet of Wisdom, I thought you might find this interesting. A friend of mine recently drew my attention to an article written by Keven Brown back in 1990 published in the journal of Baha’i Studies 2.3.1990 entitled “A Baha’i Perspective on the origin of Matter”. Keven Brown in the paper provides the following provisional translation of one of Abdu’l-Baha’s Tablets which seems to answer this question:

“the substance and primary matter of contingent beings is the ethereal power, which is invisible and only known through its effects, such as electricity, heat, and light — these are vibrations of that power, and this is established and proven in natural philosophy and is known as the ethereal substance (maddiy-i-athiriyyih). This ethereal substance is itself both the active force and the recipient; in other words, it is the sign of the Primal Will in the phenomenal world …. The ethereal substance is, therefore, the cause since light, heat, and electricity appear from it. It is also the effect, for as vibrations take place in it, they become visible. For instance, light is a vibration occurring in that ethereal substance. (Ma’ idiy-i-Asmanl 2:69)”

So probably in our modern nomenclature we would call “the ethereal power”, the quantum field.