The heads of major artificial intelligence firms pleaded with the United Nations to set controls over the burgeoning technology they are designing in order to save the world — or at least its people. Dario Amodei, chief executive officer of Anthropic, said AI could be of risk to humanity. His competitor, Sam Altman of OpenAI, said we could, as he put it, “lose control of the future to AI.” Both said the countries of the world, through the U.N. Security Council, where they testified Wednesday, have to set safeguards of some kind, which would be actual controls to prevent the technology from getting too powerful to rein in.