Time reversal method focuses wave vitality to knock over minifig targets in museum demonstration. Credit: Brian Anderson
A tabletop lined in miniature Lego minifigures. There is a whooshing sound, a pause, after which a single minifigure within the heart of the desk topples over, leaving the remaining minifigures standing.
Brian Anderson, of Brigham Young University, will focus on how that is achieved in his presentation on the 181st Meeting of the Acoustical Society of America, “Knocking over LEGO minifigures with time reversal centered vibrations: Understanding the physics and creating a museum demonstration.” The session will happen Thursday, Dec. 2.
Anderson and his staff use speaker shakers to generate vibrations in a plate. They place Lego minifigures on the plate, select a goal, and measure the impulse response between every shaker and the goal location. Playing that very response from the shakers, however reversed in time, creates sound waves that constructively intervene on the goal minifigure. The centered vitality knocks over the one Lego minifig with out disrupting the encompassing minifigs.
This demonstration was reworked right into a two-player recreation for a museum exhibit in a wave propagation museum hosted by ETH Zurich in Switzerland. Two guests take turns focusing vibrations and trying to knock over the Lego minifigures on the opposite staff.
The method additionally has quite a few purposes past Lego, and Anderson stated it reveals the facility of centered vibrations.
“Time reversal has been used to focus sound within the physique that’s intense sufficient to destroy kidney stones or mind tumors with out requiring surgical procedure,” Anderson stated. “I’ve used time reversal to find cracks or defects with ultrasound in steel buildings, akin to storage canisters for spent nuclear gasoline. Time reversal will also be used to find and characterize earthquakes or find gun pictures inside an city metropolis surroundings.”
Lego figures do not stand an opportunity in opposition to time reversal
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Lego down! Focused vibrations knock over minifigures (2021, December 2)
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