The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them. I magine releasing water in the space station and letting it float before you. It forms a spherical liquid drop. The sphere is tremulous. Touch it and it vibrates.
Waves ripple around it.
It's as though the liquid were held in a gossamer rubber bag, for a skin forms outside the liquid. That skin is called a surface layer, it's made of pure water, and it exerts a tension . The water surface pulls upon itself with the same intensity everywhere, regardless of the size of the sphere. There's no retreating from the force. Make the sphere smaller and the surface pulls just as hard.