President Donald Trump thinks no one knows what a magnet is. The polarizing president was in conversation with Fox News about the economy when he veered off track to discuss China and magnetic trains. "President Xi was willing to do the railroad things"that's magnets," he said. "Now, nobody knows what a magnet is. If you don't have a magnet, you don't have a car. You don't make a computer, you don't make, er, televisions and radios and all the other things"you don't make anything. It's a 30-year effort to monopolize a very important thing. Now, in two years, we'll have magnets, all the magnets we want. Because of tariffs, listen I called, I said you're going to play the magnet, we're going to play the tariff on you." His confusion over magnetism is well documented, and the record suggests he was being sincere when he said, "Nobody knows" what they are.