The exemplar of this era is Nvidia Corp. Its market capitalization of around $5 trillion makes it the world’s most valuable company. Jensen Huang, Nvidia’s founder and CEO, dazzled the audience at the company’s AI conference in Washington last week. In his keynote address, Mr. Huang detailed the advances Nvidia’s chips have wrought. He thanked President Trump for bringing chip fabrication back to the U.S. from Asia with energy policies that enable domestic AI microchip production.