Fredagskollokvium: The physics of touch: Using light to measure forces between objects in contact

The forces that operate when objects touch - be it your finger on your desk, a waxed ski sole on freshly fallen snow, or two droplets of vinegar in your salad dressing - determine much of how the world around us works. Knowledge about these forces can allow us to make smarter materials and devices, as well as help us understand natural processes. However, measuring contact forces is not straightforward, since it requires the simultaneous detection of deflection and surface separation on the sub-nanometer scale. In this talk, I will show how we can use the colors that arise through thin-film interference to measure forces between surfaces to atomic-scale precision. Furthermore, I will present some examples of forces that make things stick or not stick to each other, and discuss some unanswered questions about organic-mineral interfaces that we are hoping to answer within the coming years.