Cosmology and Machine Learning - What's the Biggest Challenge?

Partical physics has the ability to do experiments. You can build accelerators, and you can crash atoms into other ones at high speeds. But in economics, we're forced to learn from the data that the universe gives us. And i think is a much tougher challenge when you don't have access to this kind of experimentation. It doesn't do any good if you give your grad student, no matter how smart she is, ten terrabites of data... cause you'll never see her again.