You don't need such a heavy theorethical machinery (I mean relativity) to get to the point that distributed transactions are not possible (for some values of possible.)

Here's the link to the proof that no deterministic protocol achieves distributed certainty in presence of network failures, even for two parties only: http://en.wikipedia.org/wiki/Two_Generals%27_Problem#For_det...

And yeah, the misconceptions around that are huge. I once had to expose a totally-not-database-related API as a JDBC-compliant driver because someone insisted it would provide transactional consistency.