I find hubster's point very interesting, but I disagree. Essentially the premise is that since all of the techniques had already been developed by the baroque period, the only thing that has changed is the application of the technique. Yes, we still use the same notes, scales and chords are the same, ect. However, I have 2 points, 1. some developments have occured, and 2. the change in application in technique has been dramatic enough to constitute an evolution of music. Since Bach, the idea of scales and chords have changed. Baroque music used mostly triads, the 1-3-5 chord, and occasionally it would branch out a bit, but now we have dissonant chords. Of course, they did have the potential to make dissonant chords, but the point is, they didn't. Modern classical music has all sorts of absurd chords like the petrushka chord, where two triads are seperated by a tritone, or tone clusters. There are synthetic scales, there is the octatonic scale, ect. And rhythm has evolved tremendously. For example, the polymeter, where two different time signatures (like 4/4 and 5/4) are played at the same time, thus causing the beat to go in and out of sync with each other. Then, of course, there is the concept of distortion, which was non-existent in bach music. As for my second point, I believe it speaks for itself.
