William Falcon built a popular open source tool PyTorch Lightning used by AI researcher. Now, he's merged his startup with data center operator Voltage Park to create an "AI cloud" with a $2.5 billion valuation.© 2024 Bloomberg Finance LPLightning AI founder and CEO William Falcon began renting AI chips from data center provider Voltage Park last March to help his clients train and finetune AI models. Less than a year later, his Nvidia-backed startup is merging with the AI factory, which manages...