It's been hot in London this week. Really hot. A dangerous heat wave has hit Western Europe. Yesterday, the UK recorded its highest ever June temperature at 36.1 C (about 97 F). But as the weather app on my phone confirmed, it felt like 39 C. It's frightening that we are seeing such temperatures in...

This is today's edition of The Download, our weekday newsletter that provides a daily dose of what's going on in the world of technology. Heat waves mess with your brain. Scientists are trying to figure out why. -Jessica Hamzelou It's been hot in London this week. Really hot. A dangerous heat wave has hit Western...