The Swiss city of Basel is experimenting with special glasses for tourists. They can tour the city, while seeing a combination of today's and yesterday's worlds through these special glasses. Sometimes 'extra' people are even crossing their paths (fc, Dutch). Now this is done through a backpack full of technology, extra sensors, and thick glasses; in ten to fifteen years regular glasses will be sufficient. Now there is a big difference between today's and yesterday's images, but as time passes and history becomes more 'recent', there will also be more old material available, and these 'history' images will be of better quality (we have more images of 1990 than of 1950, and that in itself is more than 1920. Of 2010 we will have more images than of 1990, and 2030 will give us even more images than 2010). Now we see people from a certain time, later (and then we have to think 2050) we meet our father in his younger days, and can really have a conversation with him. He then will react about the same way he would have reacted in reality. The basis for this we create in our systems today. The more we register our behavior, the more predictable our behavior gets. The virtual world becomes a layer over the physical world, and it will be harder to see the differences. This development is part of that.