You may not really be aware of the automatic opening doors you walk through at the grocery store, or the emergency room, or a warehouse. But without them, you would be caught trying to open a door with your hands full, or putting yourself and others at risk of cross-contamination. In the past, people saw the need for such technology, and they developed the ideas and technology that would bring us today’s sliding entrance doors. The history of the automatic door goes way way back, to about 2000 years ago. Heron of Alexandria was a great mathematician and inventor who…