In the world of submicroscopic physics, things happen that really can't be observed. So when scientists at Johns Hopkins University need to see an example of interactions between various nanoparticles, they simply make blown-up versions of what they're studying--with Legos.
In the video above, Manuel Balvin demonstrates how different sized ball bearings move differently through a gravity-driven field of pegs. The same reaction can be assumed to work at the nano level, meaning the research can be done more practically.
And these aren't special science Legos, these are the same off-the-shelf toys that we've all loved for years. I'm imagining if we gave them a set of Robotix they could invent practical time travel.