Featured Links - June 16, 2019

Links to things that I found interesting but didn't want to do a full post about.

• Physicists See a Quantum Leap, Halt It, and Reverse It. A significant piece of research into quantum physics. 
• The Most Beautiful Theorem in Mathematics: Euler's Identity. Some beautiful and elegant math for you.
• Why Are Ebooks More Expensive Than Paperbacks? This is something I've often wondered.
• Why Boeing May Never Recover From Its 737 Debacle. It put profit over safety. 
• Native American Women Have Are Being Sold into the Sex Trade on Ships Along Lake Superior. This has been going along for years; hopefully now it can be stopped.
• Unbuilt Tokyo: 'depthscrapers' and a million-person pyramid. More from the Guardian's wonderful Unbuilt Cities series.
• A Few Fuel for Satellites Is So Safe It Won't Blow Up Humans. Say good riddance to hydrazine.