Software engineer Asier Marzo has lead a research team that created a working tractor beam with sound. They discovered a way to levitate and manipulate small objects using only a single set of speakers that are silent to the human ear. This invention could eventually be used in developing tangible, 3D holograms made of tiny particles. “I personally think this would be very useful as a centrifuge. You can imagine spinning a living cell to separate the different components,” said Marzo. Click here to view the first image in today’s viral picture gallery. Continue reading for the five most popular viral videos today, including one showing what really happens when you reply to spam email.