Milk goes sour in about a week, even if you keep it in the fridge. That's because Lactobacillus, the "good bacteria" that's found in yogurt, is constantly going about the job of oxidizing the lactose sugars in the milk into sour-tasting lactic acid - the same chemical that makes your muscles sore after exercise. But since this souring process requires the presence of oxygen, theoretically it could be slowed down even further if you kept the milk out of contact with oxygen. Rather than going with a high-tech nitrous contraption like the N2Wine globes we wrote about recently, one entrant to this year's James Dyson awards has come up with something devilishly simple: a shrinking milk jug that squeezes all the air out as you empty it. The inventor claims it lets milk last as much as a week longer. Simple and brilliant!