I would like to see some testing of subsonic drivers for deep space propulsion. As they have discovered that low frequency vibrations can produce thrust in the vacuum of space a ship outfitted with a wall of specially designed and built "subwoofer type" drivers could very well get us to much higher speeds than ever before. My concept is similar to the guy with the piezo electric drivers but going the opposite direction and using low frequency energy rather than high frequency energy. The system could even be solar powered and would require less energy than any previously or currently designed system.