William Andregg ushers me into the cluttered workshop of his startup Fathom Computing. Inside [a bulky black box is] a prototype computer that processes data using light, not electricity, and its learning to recognize handwritten digits. In other experiments the device learned to generate sentences in text. Andregg claims this is the first time such complex machine-learning software has been trained using circuits that pulse with laser light, not electricity. The company is working to shrink its [prototype], which covers a few square feet of workbench, to fit into a standard cloud server. Fathom hopes the technology will become one of the shovels of the artificial-intelligence gold rush. Tech companies, particularly large cloud providers like Amazon and Microsoft, spend heavily on computer chips to power machine-learning algorithms. Fathoms founders are betting this hunger for more powerful machine learning will outstrip the capabilities of purely electronic computers. Optics has fundamental advantages over electronics, says William Andregg. Youre already reaping the benefits of using light instead of electricity to work with data. Telecommunications companies move our web pages and selfies over long distances by shooting lasers down optical fiber. Optical computers arent likely to power your laptop or smartphone any time soon. Fathoms prototype is still too bulky, for one thing. But the technology does look to be a decent match for the main work that chips perform in AI projects based on artificial neural networks.