http://www.mountainman.com.au/aeth_faq.htm The Aether - What is it? Aether (sometimes colloquially shortened to ether) is an ancient concept dating back into antiquity. The spelling "Aether" is used to help avoid the inevitable confusion of its similarity to the chemical compound ether, thus the old saw, "Aether is the medium of space while ether is the gas that knocks you out". However, although it is technically incorrect, both spelling are currently used interchangeably. Thus, in its most basic form, aether is nothing more than a distributed physical medium permeating the entire universe, endowing it [space] with measurable physical qualities. Einstein readily acknowledged this when, in 1920 (See "Sidelights on Relativity", A. Einstein, Dover Edition 1983 Page 23), he said: "? space is endowed with physical qualities; in this sense, therefore, there exists an ether." It is more important to point out here what aether is not required to be. Aether is not a preferred reference frame (it could be, but isn't required to be). The specific properties of the aether are not defined, as should be clear, from the above basic definition. To be a preferred reference frame, the aether and matter must be assigned certain characteristics, which is encompassed by specific models of aether. It is these specific variations and conceptual models that, once defined, can be evaluated and tested. Contrary to popular myth, modern science isn't incompatible with, and does need, the aether concept. In fact, modern science could not be defined without incorporating some form of its definition into its foundation. Let's remember that the basic definition of aether is nothing more than a "physical medium permeating the entire universe, endowing it with measurable physical qualities". Currently, modern science uses the term "fields" or "fabric" instead of aether, since the term aether has become associated with a specific set of 19th century conceptual models considered to disproven and thus invalid. --------------------------------- Be a better Heartthrob. Get better relationship answers from someone who knows. Yahoo! Answers - Check it out.