Mobs and blocks despawning when you travel so many blocks away

So I created a survival world with the new beta yesterday. I lived in a village and went traveling on my horse. When I came back all the villagers were gone. I baracaided the doors so the villagers wouldn't die (because the dont close the doors now either)All the blocks I placed were gone to! It was if I never went there. Also I breed cows and before this happened with the villagers & my items when I went mining all the cows despawned.