Weirdly, spaceships have no direct way to gauge their own speed. Luckily, we can use some physics tricks to figure it out.

Founded by two veterans of Apple’s still-secret driverless car project, Aeva is a startup promising a different kind of lidar—one that can measure the velocity of objects in addition to their distance ...

This force will cause the cart to accelerate—in this case, to the left, or the opposite way it was heading, which is why it slows down during impact and even reverses direction. But what is the ...