Ether is an element that has its origins in ancient Greece and comes from the word “either,” meaning “clear sky” or “pure, fresh air.” According to Greek mythology, ether was believed to be the essence that the gods breathed. Ether was conceptualized as a material that filled the universe above the terrestrial sphere.
In his book, On The Heavens, Aristotle introduced ether as a new element in addition to the four classical terrestrial elements of Earth, Air, Fire, and Water. He proposed that the four classical elements were subject to change and moved in a linear fashion. In contrast, ether was described as being located in the celestial regions, with none of the qualities of the classical elements, and moving in a circular manner.
Ether and modern physics
In modern times, many people equate ether with a vacuum. This is because scientists seem to have realized that what we call a vacuum is not actually empty space. Thanks to quantum physics, it is now theorized that many inexplicable phenomena can be explained by the proposition that a vacuum has certain properties. Such properties can include quantum fluctuations and vacuum energy. Particles and antiparticles can come into existence and shift into non-existence in a vacuum.
Knowing the secrets of the vacuum state is a key pursuit of physics, the realization of which will unravel the mysteries of the creation of antimatter, the origin of mass, superconductivity, space, time, and so on. It is in the quantum world that the properties of the vacuum become important. Of the four fundamental forces, three of them, namely electromagnetic force, weak force, and strong force, can be explained by quantum theory in a way that is similar to the properties and concepts of a vacuum.
The fourth fundamental force, gravity, continues to be a mystery since gravitational force is far weaker than other forces at microscopic levels. Many physicists hope that sometime in the future gravity will be described in terms of a unified quantum theory. And it is possible that vacuum might be the key to such a theory. There is even a possibility that the theory of gravity may be reviewed, fundamentally.
Albert Einstein believed in the concept of ether and researched the subject in detail. One of his earliest experiments was about measuring the speed of the Earth’s movement through ether. Einstein posited that his Theory of General Relativity need not exempt ether, since rotation and acceleration can both be given physical reality through ether. He also used ether to explain the gravitational field within general relativity.
In Indian philosophy, the concept of “Akasha” comes close to the idea of ether. According to the Vedantic school, Akasha is the basis of all things that exist in the material world. In short, Akasha is the first element that is born in the universe, with all other elements being born out of it. One Vedic mantra proposes the sequence of the origin of five cardinal elements in the following manner — first came Akasha, out of which came air, from which was born fire, then came water, and finally earth.
Some schools of thought proposed that Akasha has the quality of sound and that even though it is an all-pervading physical substance, it is imperceptible to most human beings. The Buddhists believed that Akasha is divided into two categories — limited space and endless space. Some physicists have been inspired by the concept of Akasha and have proposed that there might actually be an all-pervading singular substance as the foundation of existence.