Go live Time :
To date, science has mostly only been concerned with the behavior or cause and effect of the universe. But we believe there is more to the universe than just behavior. There are also phenomenal properties like red, green, the taste of salt, and so on. These qualities are categorically completely different than mere cause and effect behavior. Our brains use these phenomenal properties to represent conscious information. We know this, and the phenomenal qualities of these properties more than we know a causal world beyond our senses, which our scientific instruments can at best imply exists. Since our scientific instruments and senses are all cause and effect based, these phenomenal properties have so far remained 'ineffable' to cause and effect observation and to other minds. You can't look at the physical behavior of whatever has a red property in our brain when we are looking at 700 nm light, and expect it to reflect 700 nm light. But that does not mean these properties are not objectively reproducible to science and objectively experiencible by others in merged and shared brains (like our right and left hemisphere are merged). Once you discover the behavioral "neural correlate" that reliably has these same phenomenal properties in everyone's mind and why, you will be able to reproduce the same set of physical state, that has this phenomenal property, in another's mind, and effectively, reliably, scientifically "eff" to the other mind these phenomenal qualities of nature. As in "Oh THAT is what salt tastes like".
To say such phenomenal properties are merely an "illusion" is a categorical mistake. Since an "illusion" is conscious knowledge that does not properly represent its referent. The nature of phenomenal properties has nothing to do with such mappings, how accurate they represent their referent, who uses different ones to represent the same referent, and so on. Conscious knowledge just is, and even if it is mistaken or different about what it represents, doesn't change its phenomenal nature and what it is fundamentally and absolutely like.
There is an intuitive argument that many think proves there can be no "phenomenal properties" or that such is irrelevant or meaningless. Hans Moravec has described this idea and called it "Transmigration". In this theory neurons are replaced, one at a time, with artificial abstract simulators producing the same "behavior" as the original on the rest of the brain. Once all the neurons are replaced with the abstract simulation of the behavior, the result will be, behaviorally, indistinguishable from the original. Chalmers has a paper related to this here: http://consc.net/papers/qualia.html. We believe that Chalmer's principle of organizational invariance will turn out to be true, and that as you replace the neurons you will get some type of experiential change in the mind going through this such as fading qualia or inverted qualia.
We believe that this realization, such scientific experiences, the mapping of such to their neural correlates, and the things we will technically be able to do as a result, will be, by far, the greatest scientific discovery to date and also have the most profound world changing effect to date. The Turing test is absurd on this issue. The only important question one should ask is something more like: "What is red like?" And you must be able to eff to properly answer such.