Personalized Quantum Mechanics Building Youth Long Sleeve T-Shirt. Quantum Mechanics Building text with a floor plan and the you are here arrows pointing to 2 different spots. Particles can be in two different places simultaneously. Can You? A humorous physics design for your favorite student, teacher, engineer or scientist at birthdays and holidays. youth long sleeve t-shirt. Shoulder-to-shoulder taping. Youth: S(6/8), M(10/12), L(14/16), XL(18/20)