The concept of the luminiferous aether dates back to ancient times, and refers to whatever fills outer space that allows us to see the light of the stars. It is sometimes said that the vacuum is empty space, and that no such aether is needed to explain the propagation of light. But that is not true either, as modern theories of light require a nonempty vacuum. Quantum electrodynamics is a perturbation theory of the aether.
The authoritative description of the 19th century aether is J.C. Maxwell's 1878 encyclopedia article. That concluded:
No theory of the constitution of the aether has yet been invented which will account for such a system of molecular vortices being maintained for an indefinite time without their energy being gradually dissipated into that irregular agitation of the medium which, in ordinary media, is called heat.Maxwell's view was that the aether was pervasive, uniform, invisible, frictionless, and permeating matter. It is sometimes said that the aether presupposed some sort of fixed coordinate system, but Maxwell does not say that.
Whatever difficulties we may have in forming a consistent idea of the constitution of the aether, there can be no doubt that the interplanetary and interstellar spaces are not empty, but are occupied by a material substance or body, which is certainly the largest, and probably the most uniform body of which we have any knowledge.
Whether this vast homogeneous expanse of isotropic matter is fitted not only to be a medium of physical interaction between distant bodies, and to fulfil other physical functions of which, perhaps, we have as yet no conception, but also, as the authors of the Unseen Universe seem to suggest, to constitute the material organism of beings exercising functions of life and mind as high or higher than ours are at present, is a question far transcending the limits of physical speculation.
What I say here is the consensus view, except that not everyone uses the word "aether". Frank Wilczek, the 2004 Nobel Prize winner in physics, wrote the book, The Lightness of Being: Mass, Ether, and the Unification of Forces:
In the first part of the twentieth century, the upheavals of relativity and (especially) quantum theory shattered the foundations beneath classical physics. Existing theories of matter and light were reduced to rubble. That process of creative destruction made it possible to construct, over the second part of the twentieth century, a new and deeper theory of matter/light that removed the ancient separation. The new theory sees a world based on a multiplicity of space-filling ethers, a totality I call the Grid. The new world-model is extremely strange, but also extremely successful and accurate.He details:
What is Space? Is it an empty stage, where the physical world of matter acts out its drama -- an equal participant, like the classical Ether, that both provides background and has a life of its own -- or the primary reality, of which matter is a secondary manifestation? Today, the third view is triumphant. Where our eyes see nothing our brains, pondering the revelations of sharply tuned experiments, discover the Grid that powers physical reality.The Higgs boson is not just some isolated particle. It is the quantization of an aether that is pervasive, uniform, invisible, frictionless, and permeating matter. And that aether is completely essential to modern physics.
The Higgs aether gives mass to the electrons and quarks, the basic constituents of matter. All electrons are identical, and have the same mass. So the Higgs is the same everywhere. The aether is the largest and most uniform body, just as Maxwell said.
You could also say that there is an electron field in a vacuum, with fluctuations making virtual electrons. But there is no net number of electrons. The Higgs aether is different in that the Higgs field is nonzero in the vacuum.