Ask a Champagne lover whether they'd prefer a bottle or a magnum, and watch what happens to their face. The eyes light up. The answer, invariably, is magnum — even among those who couldn't tell you exactly why. It turns out that instinct is correct. The magnum effect is not romantic mythology. It is physics. But what if a standard 75cl bottle could outperform a magnum? Until recently, the question was purely hypothetical. Now, it is not.