My understanding of string theory is certainly very, very limited. But I don't think it's exactly right to say it "lacks a single shred of evidence." It may and may not have evidence. True, there are few if any tests, yet, that that back it up. But some great discoveries in science were made theoretically before there was evidence for the theory. The most obvious case is Einstein's general relativity, which was proved after it was published. The first proof was through observing the deflection of starlight during a total eclipse in 1919 -- I think that was 13 years after general relativity was published. If we didn't have a moon, we could not have checked the theory at that time. Maybe I'm wrong on this, but I have the idea that aspects of Maxwell's Equations that were based on theoretical mathematical principles were later proven to be true. That is, math is a way to get at underlying reality. String theory is still in its formative stages, like a gleam in Einstein's eye. It may be hard to search for evidence when it's still an incomplete notion. But there are some indications of its validity. Again, back to Einstein: In a 1966 Time Magazine article that is available on-line (though you have to pay if you want to read the whole thing!) quotes him as saying, "The chief attraction of the theory lies in its logical completeness." String theory, as I understand it, is not yet complete though a lot of brilliant people are working to complete it. "The Official String Theory Web Sites" makes the case this way: physicists dream of a unified theory, "a single mathematical framework in which all fundamental forces and units of matter can be described together in a manner that is internally consistent and consistent with current and future observation. "And it turns out that having extra dimensions of space [as envisioned by string theory] makes it possible to build candidates for such a theory." String theory's attraction, for now, lies in what is seen as "logical completeness." Even though the theory itself isn't complete, it is seen as the logical tie that binds the macro (Einstein) and the sub-micro (quantum theory). What if we never devise a method to test it? That would not mean it is scientifically invalid. I guess what I would argue that some aspects of science might be untestable but still valid. If a theory like this fills a gap and improves our understanding, it may have validity. It should not be written off as someone spinning moonbeams. My feeling is that our intelligence is limited and our technology is even more limited. They universe is old and humanity is young. There may be tests that smarter, more advanced creatures could perform that are far beyond us. Or it may be that soon we'll come up with our own verification. I've read recently about ways that may prove string theory, though I am not familiar enough with them to talk about it now. Best wishes, Joe