All sounds are caused by _____? While many of you may be scratching your heads trying to recall your middle school science class or even hitting up Google to find the answer, the children who were at Justin Potter Library Thursday know the answer to the question. “All sounds are made by vibrations,” announced Professor Gray Beard as he presented fun experiments to show the science behind his statement.Part of the Summer Reading Program, free to all children at the downtown library every Thursday afternoon through the month of June, the educational installment featured Professor Gray Beard from Mr. Bond, the Science Guy to entertain and educate.