The document compares vacuum tubes, MOSFETs, and a proposed nano vacuum tube. Vacuum tubes are bulky and fragile but provide high power and performance, while MOSFETs are cheaper, more reliable, and have a longer lifetime but face scaling limitations. The nano vacuum tube aims to combine advantages of both by using a CMOS fabrication process with a vacuum ambient and nanoscale cathode-anode separation, potentially offering high power and performance while being cheap with a long lifetime and radiation hardness.