There’s no such thing as a complete vacuum. Even in the cosmic void between galaxies, there’s an estimated density of about one hydrogen or helium atom per cubic meter. But these estimates are largely ...

Two mathematicians have proved that a straightforward question—how hard is it to untie a knot?—has a complicated answer.

Paul Sutter is an astrophysicist at The Ohio State University and the chief scientist at COSI Science Center. Sutter is also host of the podcasts Ask a Spaceman and RealSpace, and the YouTube series ...

The driveshaft is an often overlooked, yet critically important component of a vehicle's drivetrain. Not only must it be strong enough to contend with the engine's output but it must also operate ...

The pupillary distance (PD) measurement is a requirement for people who want to purchase eyeglasses. Here, find out how to measure your PD using a mirror and a ruler. Share on Pinterest Some eyewear ...