Elon Musk certainly has a lot of ideas. Since making a fortune from PayPal in the original dotcom boom, he's founded Tesla, which popularized the electric car, and SpaceX, the rocket company that now flies plenty of NASA payloads. Two newer companies — the Boring Company, focused on digging holes for transit tunnels, and NeuraLink, which is developing brain-computer interfaces — also occupy his time. Then there's the Hyperloop, the high-speed land travel design he's encouraged others to develop. Somehow, this brash billionaire still has time to get himself into trouble on Twitter. For a weekly digest, subscribe to our This Week in Elon newsletter here.