A suction cup is a common object that most people never put much thought into, but they are fascinating in their simplicity.
When suctioned to a smooth, non-porous surface, the internal pressure is reduced below that of the surrounding atmosphere, creating a partial vacuum. The outside air would quickly fill this void, but as long as a good seal is maintained, the air is unable to squeeze between the surface and the suction cup.
Humans have been using suction cups since the 200s BCE when gourds were used for suction in ancient medicinal rituals. Modern suction cups, patented in 1868 as “atmospheric knobs” use improved materials, but are still quite simple.
This industrial strength suction cup can hold up to 110lb (50kg). In addition to lifting smooth objects, it can also be used to remove dents from cars.