I always wanted to build a "periscope windows". Have a large light-gathering lens on the outside, then focus the rays into a much thiner "sun tunnel", bring th

I always wanted to build a "periscope windows". Have a large light-gathering lens on the outside, then focus the rays into a much thiner "sun tunnel", bring them underground (in the same shaft as the water and heating pipes), then expand the rays into a fake window. If this was possible it would completely change the way we build homes, we could have many underground floors with "periscope windows" and a towers of light gathering lenses on the roof. Unfortunately this is not physically possible, not just a real picture but not even the light can be made parallel this way. (Maybe some quantum tech will make this possible one day.)