But they're also some of the Indo-European languages least similar to proto-indo-european. I don't know what about stress patterns and phonology, but in terms of morphology and syntax the Slavic languages are probably the closest to the original PIE.

My degree was in Physics and Math and I believe in hard data-driven measurable science. It just seems likely that too much of the required data cannot be verifiably determined from extrapolating trends in written language and speech over the centuries. Extrapolations over millenia seems like too much guesswork. It…

Yeah, this sounds more germanic/gaelic than anything else to me... still, the actual sound of ancient languages is something that's always fascinated me. I've read a couple articles about the study and it doesn't seem like we'll ever have a concrete "this is totally what they sounded like" moment.