This has been answered in some detail by the Universal House of Justice. I am only posting this because it has become a discussion that needs this clarification.
People can choose to read it if they are so inclined to do so.
"With reference to your question about the “ether,” the various definitions of this word as
given in the Oxford English Dictionary all refer to a physical reality, for instance, “an
element,” “a substance,” “a medium,” all of which imply a physical and objective reality
and, as you say, this was the concept posited by nineteenth century scientists to explain
the propagation of light waves. It would have been understood in this sense by the
audiences whom ‘Abdu’l‑Bahá was addressing. However, in Chapter XVI of Some
Answered Questions, ‘Abdu’l‑Bahá devotes a whole chapter to explaining the difference
between things which are “perceptible to the senses” which He calls “objective or
sensible,” and realities of the “intellect” which have “no outward form and no place,” and
are “not perceptible to the senses.” He gives examples of both “kinds” of “human
knowledge.” The first kind is obvious and does not need elaboration. To illustrate the
second kind the examples He gives are: love, grief, happiness, the power of the intellect,
the human spirit and “ethereal matter.” (In the original Persian the word “ethereal” is the
same as “etheric.”) He states clearly that “Even ethereal matter, the forces of which are
said in physics to be heat, light, electricity and magnetism, is an intellectual reality, and is
not sensible.” In other words, the “ether” is a concept arrived at intellectually to explain
certain phenomena. In due course, when scientists failed to confirm the physical
existence of the “ether” by delicate experiments, they constructed other intellectual concepts to explain the same phenomena.
In considering the whole field of divinely conferred “infallibility” one must be careful to avoid the literal understanding and petty-mindedness that has so often characterized discussions of this matter in the Christian world. The Manifestation of God (and, to a lesser degree, ‘Abdu’l‑Bahá and Shoghi Effendi,) has to convey tremendous concepts covering the whole field of human life and
activity to people whose present knowledge and degree of understanding are far below His. He must use the limited medium of human language against the limited and often erroneous background of His audience’s traditional knowledge and current understanding to raise them to a wholly new level of awareness and behavior. It is a human tendency, against which the Manifestation warns us, to measure His statements against the inaccurate standard of the acquired knowledge of mankind. We tend to take them and place them within one or other of the
existing categories of human philosophy or science while, in reality, they transcend these and will, if properly understood, open new and vast horizons to our understanding."
Regards Tony
